CA2078651A1 - Wash composition, test kit and method for determination of microorganisms associated with periodontal diseases - Google Patents

Abstract

WASH COMPOSITION, TEST KIT AND METHOD FOR DETERMINATION
OF MICROORGANISMS ASSOCIATED WITH PERIODONTAL DISEASES
Abstract of the Disclosure An aqueous wash composition has been found useful in methods for determination of specific binding ligands. The composition is buffered to a pH of less than or equal to 6 or greater than or equal to 9. It also includes as its essential component at least about 0.1 weight percent of an anionic surfactant which is represented by the formula:
[A-SO3+y]-(1+y) [X+m]n wherein A is a hydrocarbon having a molecular weight of at least about 180, X+m is hydrogen or a monovalent or divalent cation, m is 1 or 2, y is 0 or 1, and n is 1 or 2 provided that m and n are not both 2. Optionally and preferably, the wash composition also includes a nonimmunoreactive protein. This wash composition is particularly useful in methods for determination of microorganisms associated with periodontal diseases.
Such methods can be of a variety of formats, but immunometric assays are particularly useful. The wash composition can be included as part of a diagnostic test kit.

Description

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WASH COMPOSITION, TEST :gIT AND METHOD FOR DETERMIN~TION
OF MICROORGANISMS ASSOCIAq~ED WITH PERIODON~AL DISEASES
Field of the In~en~ion The pres~nt invention relates to an aqueous wash composition, a diagnostic test kit and a method for using the wash composition to determine microorganisms associated with periodontal diseases.
In particular, the method is useful for the determination of any of the microorganisms Actinobacill~s acti~omycetemcor~ OE , P~evo~ella interm~edia (formerly known as Racteroi~e$ intenmediu~) or ProDhyromonas ~in~ivalis (formerly known as Bac~eroides qin~ivali~).
Back~round of the In~ention There is a continuous need in medical practice, research and diagnostic procedures for rapid, accurate and qualitative or quantitative determinations of biological substances which are present in biological fluids at low concentrations. For example, the presence of drugs, narcotics, hormones, steroids, polypeptides, prostaglandins or infectious organisms in blood, urine, saliva, vaginal secretions, dental plaque, gingival crevicular fluid and other biological specimens has to be determined in an accurate and rapid fashion for suitable diagnosis or treatment.
To provide such determinations, various methods have been devised for isolating and identifying biological substances employing specific binding reactions between the substance to be detected (sometimes identified as a Rligand~) and a compound specifically reactive with that substance (sometimes identified as a ~receptorD).
After the formation of a specific binding complex between ligand and receptor, it is usually necessary to separate the complex from uncomplexed materials. A most common specific binding reaction 207~$1 involves an antigen (or antigen-like material) and its corresponding antibody which form an immunological complex. Uncomplexed antigen and antibodies are generally separated from the complex using various ~5 techniques. For example~ separation may be accomplished by filtration, centrifugation or affinity chromatography. However, in most assays, the complex is solubilized and uncomplexed materials are washed from it. Common wash solutions include distilled water, various buffers and a n~er of solutions containing nonionic, anionic or cationic surfactants.
It has been found, however, that not every wash solution will effectively remove uncomplexed materials in every type of assay for a specific ligand.
By effectiveness is meant that the uncomplexed materials are removed to such an extent that the assay result reflects only the presence of complexed materials with minimal background or cross-reactivity between the ligand and non-specific binding proteins.
Thus, what may be useful as a wash composition for one assay is not necessarily useful in another. If the wash composition is ineffective, unwanted background may be present thereby obscuring the true assay result.
One undesired result would be n false positives R from ~5 too high background or cross-reactivity. Another undesired result would be a true positive, but the background could obscure the magnitude of the positive result.
Specific microorganisms have been implicated as indicators for a number of periodontal diseases in humans and animals, such as gingivitis and periodontitis. The importance of such diseases is growing in the human population, especially as people live longer, and prevention of such diseases is becoming of considerable importance to dentists, insurance carriers and the health industry in ge~eral.

~7~6~1 In addition, proper dental care for animals is a growing concern in our culture.
Detection of microorganisms associated with periodontal diseases has been accomplished using culture techniques, DNA probes and a number of immunological procedures, such as agglutination assays, enzyme linked immunosorbent assays (ELISA) and others known in the art. ELISA utilizes the reaction of an extracted antigen from the microorganism(s) and the corresponding antibody to form an immunological complex. As noted above, usually uncomplexed materials are washed from the complex in order to provide an accurate assay result.
An advance in the art in the detection of microorganisms associated with periodontal diseases is described and claimed in Canadian Patent No. 2,028,681.
This case describes the simultaneous detection and differentiation of these microorganisms, and particularly ~s5innk~ç~ actinomycetemcomitan~, Porphyromonas inqivalis and Prevo~tell~ in~erme~ , in an immunometric (also known as ~sandwich~) assay using water-insoluble reagents in defined regions of a microporous filtration membrane. During the assay, uncomplexed materials were washed through the membrane using a common wash solution of sodium decyl sulfate in water (pH 7).
While the noted simultaneous assay represents an important advance in the art for detecting the noted micoorganisms, in some cases, false positives were observed when a specimen containing high levels of one or more of the three microorganisms was contacted with the different regions of the membrane substrate containing the antibody reagents. A solution to this problem is critical since it is highly important for the user of the assay to discriminate among the microorganisms for effective diagnosis and treatment of 2 ~

disease without significant apparent cross-reactivity between an antigen and non-specific antibodies.
Summ~y Qf t~ç InventiQn The problem noted above was solved by using a -~5 very specific wash composition in the assay. ~hisaqueous wash composition is buffered to a pH of less than or equal to about 6 or greater than or equal to about 9, and comprises at least about 0.1 weight percent of an anionic surfactant which is represented by the formula:

[A-SO3~y]-(1~y) [X~m]n wherein A is a hydrocarbon having a molecular weight of at least about 180, x+m is hydrogen or a monovalent or divalent cation, m is 1 or 2, y is 0 or ~, and n is 1 or 2 provided that m and n are not both 2.
This invention also provides a diagnostic test kit useful for the determination of a specific binding ligand, comprising, in individual packaging:
~1) the aqueous wash composition described above, and (2) a receptor for a target specific binding ligand.
Moreover, a method for the determination of a microorganism associated with periodontal disease comprises the steps of:
A. forming a water-insoluble complex of an antigen extracted from a microorganism associated with periodontal disease with an antibody specific for the antigen, B. separating uncomplexed materials from the water-insoluble complex by washing with the aqueous wash composition described above, and C. detecting the water-insolubl~ complex as a determination of the microorganism.

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The present invention resides in the use of a particular wash composition which has been shown to reduce or eliminate false positives in assays, particularly in assays for micxoorganisms associated with periodontal diseases. However, it is to be understood that the efficacy of the wash composition is not limited to the specific embodiments demonstrated herein, but it can be used in any type of specific binding assay whereby uncomplexed materials are removed from an insolubilized complex.
The wash composition of this invention provides the noted advantages due to the presence of the defined anionic surfactant, and hecause of its specific pH, that is either e~ual to or greater than about ~, or e~ual to or less than about 6. As is demonstrated below, conventional wash solutions having the neutral pH (that is, about 7) do not solve the noted problem. Moreover, a wide variety of surfactants were tried, and only those of the recited formula solved the problem.
Brief Descri~tion ~f_~he prawin~s FIG. 1 is a bar graph representation of dye signal data obtained from the assays described in Example 1 below in comparisons with Controls A and B.
FIG. 2 is a bar graph representation of dye signal data obtained from ~he assays described in Example 2 below in comparisons with Controls A, C and D.
FIG. 3 is a bar graph representation of dye signal data obtained from the assays described in Example 3 below in comparisons with A, B and E-H.
FIG. 4 is a bar graph representation of dye signal data obtained from ~he assays described in Examples 4 ancl 5 below in comparisons with Controls A
and I-Q.

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FIG. 5 is a bar graph representation of dye signal data obtained from the assays described in Examples 6-8 below in comparisons with Controls A and R-U.
FIG. 6 is a bar graph representation of dye signal data obtained from the assays described in Examples 10-16 below using various wash compositions of this invention.
Details of ~he Inv~ntion The present invention provides a wash composition and diagnostic test kit that can be used in any specific binding assay whe:reby a ligand of interest is complexed with its corresponding receptor, and uncomplexed materials are removed by washing prior to complex detection. Ligands which can be so complexed are well known in the art and include, but are not limited to, antigenic proteins and carbohydrates, toxins, lectins, drugs, enzymes, steroids, vitamins, polysaccharides, glycolipids~ alkaloids, microorganisms, viruses, protozoa, haptens, antibodies, avidin and its derivatives, biotin and its derivatives, nucleic acids, amino acids, peptides, polypeptides, glycopeptides and any components of the foregoing materials. Preferably, this in~ention is used in the detection of immunological materials which are defined herein as materials, which when injected into an immunocompetent host, will produce an immunological response ~that is, cause the production of antibodies specific to those materials), as well as the antibodies so produced.
The method to detect a ligand of interest can be used to assay any human or animal biological ~luid or specimen of interest including, but not limited to, ~hole blood, plasma, sera, lymphatic ~luid, bile, urine, spinal fluid, seminal fluid, vaginal secretions, sputum, perspiration, stool specimens, fluid 2 ~ 7 ~ ~ 3 ~

preparations of tissues, periodontal tissue, dental plaque, crevicular fluid and saliva.
It is to be understood that while the remaining discussion is directed to microorganisms associated with periodontal diseases, the use of the kit and wash composition is not so limited. Rather, the following discussion is provided merely for exemplification.
The wash composition of this in~ention is an aqueous buffered solution which keeps background low, especially when several ligands are being detected simultaneously in the same test device. This is seen in the examples below relating to simultaneous detection of microorganisms associated with periodontal diseases.
The wash composition is buffered to any suitable pH although it is preferred to have either a relatively high pH, that is about 9 or above, or a relatively low pH, that is about 6 or below. More preferably, in the higher pH range, the pH of the composition is from about 9.5 to about 11 with a pH of about 10 being most preferred. If the p~ is below about 6, it is preferably in the range of from about 4 to about 6.
The appropriate pH can be pro~ided by the use of an appropriate amount of one or more appropriate buffers (with or without added base or acid, depending upon the pH desired). Organic or inorganic buffers which are well known in the art include, but are not limited to, glycine, phosphate, succinic acid, 2-(4-morpholino)ethanesulfonic acid, 3-(cyclohexylamino)-1-propanesulfonic acid, 3-cyclohexylamino)-2-hydroxy-1-propanesulfonic acid, 2-(N-cyclohexylamino)ethane-sulfonic acid, and any others which provide buffering at the desired pH and which do not ad~ersely affect the specific binding complex being washed. The amount of 2~8~

each buffer would depend upon its buffering strength and what pH is desired. This could be readily determined by one of ordinary skill in the art, and generally is at least about 0.05 molar. Glycine is a preferred buffer for the high pH range, and succinic acid or 2-(4-morpholino)ethanesulfonic acid is a preferred buffer for the low pH range.
Contained in the was]h composition is an essential anionic surfactant which is represented by the formula:

[A-SO3+y]~(l+Y) [X~m]n wherein A is a hydrocarbon having a molecular weight of at least about 180, x+m is hydrogen or a monovalent or divalent cation, m is 1 or 2, y is 0 or 1, and n is 1 or 2 provided that m and n are not both 2.
More specifically, in the noted formula, A is a linear, branched or cyclic hydrocarbon having from 13 to 18 carbon atoms, and thus a molecular weight in thP
range of from about 180 to about ~50. Such hydrocarbon groups include, but are not limited to, linear and branched alkyl (for example, tridecyl, tetradecyl, and branched equivalents), cycloalkyl having one or more alkyl substituents (for example, cyclohexyl substituted with linear or branched C7 or higher alkyls or a plurality of lower alkyls) and aromatic carbocycles ha~ing one or more alkyl substituents (for example, phenyl substituted with C7 or higher alkyls). When A has more than 16 carbon atoms, it is alkylcyclyl, preferably alkylphenyl.
Moreover, in such cases, the cyclyl group can be substituted with more than one alkyl. It is important that the hydrocarbon not be so large that the surfactant loses its water solubility or dispersibility.

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g In one preferred embodiment, A of the noted formula is an alkyl or alkyl-substituted phenyl having a molecular weight of from about 180 to about 250. The alkyl has from 7 to 12 carbon atoms, and is linear or ;5 branched. Useful alkyl groups are, for example, n-octyl, isooctyl, ~-decyl, 2,2-diethylbutyl, 2-ethyldecyl and dodecyl. A useful anionic surfactant of this embodiment is available commercially ~rom A~CO
under the trademark ULTRAWET 63L.
In another and more preferred embodiment, the anionic surfactant has the noted formula above wherein A is linear or branched alkyl having from 14 to 16 carbon atoms (for example, tetradecyl, hexadecyl, 2-ethyltetradecyl and 2,2-dimethyltetradecyl).
Preferably, A is tetradecyl. One useful anionic surfactant, a tetradecyl sodium sulfate, is commercially available from Union Carbide Corp. under the trademark TERGITOL 4.
Also in the ~oregoing formula for all preferred embodiments, m and y are both 1, and n is 2.
Generally, x+m is hydrogen or a monovalent or divalent cation from Groups IA or IIA of the Periodic Table, such as alkali metal ions (for example, sodium, potassium and rubidium) and alkaline earth metal ions (for example, magnesium, calcium and strontium).
Alkali metal ions such as sodium and potassium ions are preferred. Howe~er, the cation can also be an ammonium or an organic cation such as trialkyl- or tetraalkylammonium ions, for example ions formed from di- and triethanolamines, such as di- and tri(~-hydroxyethyl)ammonium, and from trialkylamines, tetramethylammonium and others readily apparent to one skilled in the art, and arylammonium cations such as trimethylphenylammonium and cyclic onion cations, such as 1-methylpyridinium, 3-methylimidazolium and other readily apparent to one skilled in the art.

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The anionic surfactant can be present in the wash composition in any amount which is effective to provide the washing needed in a given assay. This amount can vary widely depending upon the concentration .
;5 of the ligand to be determined, the assay format and the sensitivity of the detection means. Thus, where the ligand is present in high concentration and the detection means is highly sensitive, washing may not be as critical and the anionic surfactant concentration need not be high. Under the opposite conditions, the amount of surfactant desired would be higher.
Generally, the amount can be at least about 0.1 percent, based on the composition weight, with from about 1 to about 5 weight percent being more preferred.
Preferred wash compositions also include one or more nonimmunoreactive proteins, such as serum proteins (such as fetal calf serum, bovine serum albumin), casein and other mil~ proteins, fibrinogen and others readily apparent to one of ordinary skill in the art. These proteins are defined as ~nonimmuno-reacti~e" because they do not participate in the specific binding reactions of the assay. They are present in order to aid in the action of the buffered surfactant in reducing non-specific binding. They can be present in an amount of at least about 0.1 weight percent, and preferably from about 0.4 to about 0.6 weight percent.
The wash composition can be prepared merely by mixing the anionic surfactant, and optionally nonimmunoreactive protein, in a suitable buffer. It can be used immediately in an assay, or stored in a suitable container for later sale or use, for e~ample ~s part of a diagnostic test kit.
Such kits can include, in individual packaging or containers, the wash composition and a receptor for the specific binding ligand of interest.

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--ll--The receptor can be water-soluble and detectably labeled (for example with an enzyme or other labeling means) or immobilized on a suitable substrate. Other components of a kit can include detection means such as dye providing compositions (described in more detail below), assay devices, extract:ion compositions, insolubilizing reagents (descr:ibed below), instructions, pipettes and other apparatus needed for a typical assay. In a preferred embodiment, the kit includes a disposable test device (described below), and a receptor (for example, an antibody) for the ligand which is immobilized on a particulate substrate, membrane (including polymeric and cellulosic filters), cellulosic sheet or polymeric film. Such a kit can be assembled and sold with all components present, or provided as individual parts prior to use in an assay.
As noted above, the wash composition and test kit can be used in the determination a wide variety of specific binding ligands. In a preferred embodiment, microorganisms associated with periodontal diseases are determined, and the remainder of this description of the assay methods will be directed to that embodiment.
In such cases, the ligand to be determined is an antigenic material and the receptor therefor is an antibody.
In particular, the microorganisms Actinob~cill~ ac~inomycetemcQmitans, por~ QmQea~
ainqivali~ and Preyo~ la intermedia are determined, either individually or collectively, using the present invention. However, other microorganisms which are suspected of being associated with periodontal diseases can also be detected or differentiated with this invention. Such other microorganisms include, but are not limited to, Wol~nella recta, Bacteroides forsythus, Eikenel~a ~ç~od~ns, F~so~ac~çr um n~çlea~u~ and Tre~onema ~5iC~ola. In some embodiments, it is 2~7~

irrelevant as to which serotypes of any of the microorganisms may be present. In other embodiments, the invention can be used to differentiate among serotypes of a single species as well as among species.
~5 The method of this invention is generally qualitative although the amount of specific binding complex can be observed and coxrelated to the amount of ligand in a specimen. Thus, the assay can be quantitative also. While the ;Ligands determined can be intact microorganisms, it is preferred to extract the ligand (for example a lipopolysaccharide, capsule antigen or outer membrane protein) of interest from the host organism. For periodontal assays, such antigens can be extracted from saliva, mucous from the throat or mouth, human or animal tissue extracts, dental plaque or gingival crevicular fluid.
Antigen extraction from the noted microorganisms can be accomplished using suitable physical or chemical means such as use of a detergent (for example sodium deoxycholate, sodium dodecyl sulfate or sodium decyl sulfate~ following known procedures (see US-A-4,741,999), osmotic shock [see for example, Dirienzo et al, Infect. & Immun., 47(1), pp.
31-36, 1985] or sonic means [see for example, Zambon et al, Infect~ & Immun., 41(1), pp. 19-27~ 1983].
A preferred extraction procedure is demonstrated in Example 1 below using a high pH
composition of a cationic surfactant and an anionic surfactant.
If desired, the extracted antigen can be removed from the original specimen, or the original specimen can be su`itably diluted with buffer or water, Gr filtered in order to remove extraneous matter and facilitate complexation of antigen with the corresponding antibody in the assay.

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Antibodies useful in the practice of this invention can be monoclonal or polyclonal. Monoclonal antibodies can be prepared using standard procedures, such as those described in US-A-4,741,999. Polyclonal ;S antibodies can also be produced using standard procedures, such as described by Zambon et al, ~X~.
Generally, a mammal is immunized one or more times with a suitable ~uantity of an antiS~enic component or whole bacterial cells of the organism. After a suitable time, when the titer is acceptable, antisera is recovered from the mammal. Antibodies can be removed from antisera and purified if desired using }cnown procedures and stored in frozen buffered solutions until used. A preferred method for providing highly specific polyclonal antibodies generally calls for injecting a mammal with an immunizing amount of ~n antigen a first time, injecting the mammal a second time between the second and fourteenth days after the first injection with a boosting amount of the antigen, and beginning the fifte~nth day after the first injection, injecting the mammal at least three times every seven day period for at least four seven~day periods with a boosting amount of antigen. An immunizing amount and boosting amount can be readily determined by a skilled worker in the art. After the last booster injection, antisera is removed from the mammal.
After extraction of antigen and provision of antibodies specific to that antigen, the method of this invention is carried out by forming a water-insoluble immunological complex of the antigen and antibody.
This complex formation can be accomplished in a number of procedures and the present invention is not limited to a specific procedure even though the ~sandwich~
assays described in detail below are most preferred.

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In one embodiment, the extracted antigen can be insolubilized by direct adsorption or covalent attachment to a solid substrate, such as a particulate substrate (for example, polymeric or glass particles), filtration membranes, cellulosic filter papers, solid polymeric or resin-coated films, glass slides or walls of test tubes, glass or polymeric cuvettes and other substrates readily determinable by one of ordinary skill in the art. Such assays are generally known in the art as rdirect binding~ assays whereby the antigen directly binds to the substrate, and antibodies are used to complex with the insolubilized antigen. The antibodies can be detectably labeled to make the complex detectable, or the complex can be detected using an anti-antibody which is suitably labeled and specific to the first unlabeled antibody. Detection of the complex can be effected after washing using known techniques. Further details of how direct binding assays are carried out are provided for example in US-A-4,497,899 and Canadian Patent No. 2,032,114~
Another embodiment of the method of this invention is an agglutination method whereby antibodies to the extracted antigen are affixed to small particles in some manner and the particles which are detectable by light scattering or by the presence of a tracer such as dye or radioisotope within the particles. The resulting immunoreactive complex is formed through the reaction of antigen with antibodies on the particles, and can be detected using known procedures after washing. Technical details regarding agglutination assays are provided, for example in US-A-4,847,199.
Examples of other use~ul assays include competitive immunoassays and enzyme-linked immunoabsorbent assays (commonly known as ELISA). Such assays are described generally in US-A-4,427,782 and by 2~7~6~1 Schmeer et al, J.C~ln.MicrobiQl~, 15(5), pp. 830-834 (1982).
A preferred embodiment of this invention is an immunometric or sandwich assay in which the extracted antigen is reacted at different epitopic sites with two antibodies, one of which is detectably labeled, and the second being immobilized (or capable of being immobilized such as through avidin-biotin complexation or other specific binding reactions).
Suitable substrates on which one antibody is immobilized incl~de those notecl abo~e for direct binding assays. Preferably, particulate carrier materials formed from organisms, natural or synthetic polymers, glass, ceramics, diatomaceous earth or magnetizable particles are used. These particles are more preferably polymeric, spherical in shape and have an average particle size (in largest dimension) of from about 0.01 to about 10 ~meters, althou~h the size, structural and spatial configurations are not critical.
The general procedures for immunometric assays are described, for example, in US-A-4,37~,110 and US-A-4,486,530.
The antibodies can be attached to particulate carrier materials to form water-insoluble immunological reagents by physical or chemical means, including adsorption or covalent reaction with reactive groups on the surface of the materials. Covalent attachment is preferred for better assay sensitivity. Many useful reactive groups are knot~n in the art for antibody attachment, which groups can be part of the chemical structure of the carrier material, or added by coating or chemical treatment of an inert material. One skilled in the art would readily understand how to prepare such materials to have any of the following reactive groups: carboxy, 2-substituted ethylsulfonyl, vinylsulfonyl, epoxy, aldehyde, active halo atoms, ~0~6~

amino, hydrazide and active esters such as succinimidoxycarbonyl.
Particularly useful particulate carrier materials are polymeric beads described, for example, ; 5 in EP-A-0 323 692 (published ~July 12, 1989) which are prepared from one or more ethylenically unsaturated polymerizable monomers having an active halo atom, activated 2-substituted ethylsulfonyl or vinylsulfonyl groups. Other particularly useful particles having reactive carboxy groups are described in C~anadian Patent No. 2,043,089.
Homo- and copolymers described in EP-A-0 323 692 include the following representative materials:
poly(m & ~-chloromethylstyrene), poly(st~rene-co-m ~ ~-chloromethylstyrene-co-2-hydroxyethyl acrylate) (67:30:3 molar ratio), poly[styrene-~Q-m & -(2-chloroethylsulfonylmethyl)styrene] (96:~ molar ratio), poly{styrene-co-N- [m ~ 2-chloroethylsulfonyl-methyl)phenyl]acrylamide} (99.3:0.7 molar ratio), poly (m ~ ~-chloromethylstyrene-co-metharylic acid) (95:5 molar ratio), poly[styrene-ço-m & ~-(2-chloroethylsulfonylmethyl)styrene-co-methacrylic acid]
(93.5:4.5:2 molar ratio~ and poly[styrene-Q-4-(2-chloroethylsulfonylmethyl)styrene] (95.5:4.5 molar ratio).
Procedures for attaching antibodies to particles having reactive groups are well known, as described for example in US-A-3,925,157. US-A-4,181,636, US-A-4,703,018 and EP-A-0 323 692. In general, the antibodies are mixed with the particles under suitable conditions depending upon the attachment form (adsorption, covalent or use of a linking group).
A worker skilled in the art would readily know what conditions should be used for each procedure. For example, for attachment to particles having reactive halo atoms, activated 2-substituted ethylsulfonyl or vinylsulfonyl groups, the antibodies are generally mixed with the particles for up to 2~ hours at a temperature of from about 20 to about 40C in a-.~ suspension buffered at a pH of trom about 7 to about10. If carboxy groups are used for attachment, the well known carbodiimide acti~ators can be used, as well as carbomoylonium compounds are described in EP-A-0 308 235. Antibodies can be absorbed on particles by incubating particles and antibodies in suspension at suitable temperature for several hours.
More preferably, the immunological reagents described above are coated or deposited on a microporous filtration membrane which is inert to chemical or biological reactions. It is generally composed of one or more natural or synthetic substances which have sufficient integrity for reagents to react or be affixed thereto without loss of form or function.
It is porous enough for filtration needed to remove substantially all uncomplexed materials from the complexes formed thereon. Useful membrane materials include, but are not limited to, porous natural or synthetic polymers, sintered glass, membranes of glass or polymeric films or fibers, ceramic materials, cellulosic materials and particulate structures composed of beads bound together with an adhesi~e or binder material. The membranes are generally flat, but some irregularities in the surfaces are acceptable, as well as some curvature if it is desired. One skilled in the art would be able to identify other useful materials which are commercially available or prepared using known techniques. Particularly useful materials are treated or untreated polyamide microporous mombranes such as those commercially a~ailable from Pall Corp. under the trademarks LOPRODYNE~ and BIODYNE:TM

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The membrane generally has an avera~e pore size in the largest dimension of from 0.5 to about 5 ~meters, although smaller or larger pores would be acceptable as long as the comp:Lexes formed remain on ;S the membrane and fluid drainage is not adversely affected.
If desired, the membrane can be coated with surfactant or nonimmunoreactive protein (such as casein or succinylated casein), as known in the art to reduce nonspecific interactions or to promote desired filtration.
The water-insoluble immunological reagents having appropriate antibodies can be affixed to the membrane over its entire surface or in defined regions thereof. Affixation is accomplished using any mechanical means such as coating, dipping, printing or spraying or fixed by covalent means. Generally, they are coated and dried on the membrane prior to use.
They can be used in admixture with hydrophilic binders to provide additional integrity to the coating.
The membrane can be hand held in the assay to provide sites for complexation of extracted antigen and the antibodies thereon. However, preferably, the membrane is disposed or mounted in a disposable test device or article having a suitable frame and structure for holding the membrane and fluid which is drained therethrough. Many such test devices are known in the art, including but not limited to those shown in US-A-3,825,410, US-A-3,888,629, US-A-3,970,429, US-A-4,446,232, US-A-4,833,087, US-A-4,847,199, US-A-4,921,677 and US-A-4,923,680. Particularly useful test devices are those marketed by Eastman Kodak Company under the trademark SURECELLTM test devices.
Preferred test devices have three test wells designed for providing both negative and positive 207~

control results as well as a specimen test result.
Each test well contains a membrane as described herein.
Once the water-insoluble complex of antigen and antibodies is formed (pref~erably on the membrane), .5 the complex is washed with the wash composition of this invention to remove uncomplexed materials prior to detection of the complex. If the complex is on a substrate that does not allow Eluid drainage, the uncomplexed materials and fluid can be decanted off or otherwise removed. Where a meInbrane or filter is used, the fluid and uncomplexed materials flow through the membrane or filter and the complex of interest is left thereon.
Depending upon the means of detection, the water-insoluble complex can then be detected using a number of standard reagents and methods. For example, the complex may be detected without tracers or signal producing labels using light scattering techniques known in the art. Agglutinates can be similarly detected.
Preferably, however, whether the assay format is a direct binding assay or immunometric assay, the immunological complex is detected by means of a detectable label on the water-soluble receptor (such as an antibody). Such labels can include, but are not limited to enzymes, avidin, biotin, radioisotopes, fluorogens and chromogens. Enzymes are preferred and can be used to generate colorimetric, fluorometric or chemiluminescent signals which can be evaluated with the unaided eye or using standard spectrophotometric equipment to measure electromagnetic density, spectra or intensity. Useful enzymes include, but are not limited to peroxidase, urease, alkaline phosphatase, acid phosphatase, glucose oxidase, ~-galatosidase, glucosidase and others readily apparent to one skilled 2~8~

in the art. Alkaline phosphatase and peroxidase are preferred wlth peroxidase being most preferred.
For a given enzyme label, there are various known compositions which provide detectable colorimetric, fluorometric or chemiluminescent signals in the presence of the enzyme. For example, one preferred embodiment utilizes a dye-providing composition which provides a dye in the presence of the enzyme through one or more chemical reactions. A
number of leuco dyes are known to be useful for this purpose where peroxidase is the label including those described in US-A-4,0~9,747 and US-A-~,670,3~6. ~
preferred dye-providing composition is illustrated in the examples below.
Alternatively, the enzyme label can be used in one or more reactions to produce a chemiluminescent signal, such as described for example in US-A-4,647,532, US-A-4,835,101, US-A-4,729,950 and US-A-~,598,044. Other labels besides enzymes can also be used to produce chemiluminescent signals.
In the preferred immunometric assay, at some point the antigen is contacted with a detectably labeled water-soluble antibody. This can occur prior to, simultaneously with or subseq~ent to the formation of the immunological complex, but generally prior to washing with the wash composition of this invention.
Thus, the complex of antigen and two antibodies is left on the preferred membrane when uncomplexed materials are washed through. Following formation of this sandwich complex and washing, detection is carried out using reagents and procedures described generally above.
Positive or negative controls can be carried out simultaneously with assay of the specimen.
Depending UpOIl the signal being produced for detection, appropriate reagents can be added to stop signal -21- ~07~
production, for example by adding reagents to stop the formation of a dye or production of light by chemiluminescence. These materials are well known in the art.
.5 In a preferred method for the de~ermination of a microorganism associated with periodontal disease, the method comprises the steps of:
A. contacting an aqueous specimen suspected of containing an antigen extracted from a microorganism associated with periodontal disease with a microporou~
filtration membrane having thereon, in-a discrete zone of a surface of the membrane, a water-insoluble reagent comprising water-insoluble particles having affixed thereto antibodie-s specific to the antigen, to form, in the zone, a water-insoluble complex between the antibody and the antigen, B. contacting the water-insoluble complex with a detectably labeled second antibody specific to the antigen to form a detectably labeled, water-insoluble sandwich complex in the zone, C. simultaneously or subseguently to step B, separating uncomplexed materials from the labeled, water-insoluble sandwich complex by washing the uncomplexed materials through the membrane with the aqueous wash composition described herein, to separate uncomplexed materials from the labeled, water-insoluble sandwich complex, and D. detecting the labeled, water-insoluble sandwich complex as a determination of the microorganism in the specimen.
More preferably, the method just described is useful for the simultaneous determination or differentiation of a plurality of such microorganisms ~iherein the membrane has a plurality of distinct and independent zones containing distinct water-insoluble reagents for each of the specific microorganisms of 207~:3 .~

interest. Any or all of the microorganisms ~tino~acillus actinomycetemcQm~tan~, Prev~ella intenmedi~ and Por~yromonas gingiYali~ can b~
determined in this manner.
.5 Another embodiment of this invention is an immunoassay for detecting the presence or amount of a water-insoluble complex formed from an antigen extracted from a microorganism associa~ed with periodontal disease and an antibody specific to the antigen, comprising:
A. separating the water-insoluble complex from uncomplexed materials by washing with the aqueous wash composition described herein, and B. detecting the separated water-insoluble complex or the uncomplexed materials washed from the complex.
Uncomplexed materials can be readily determined using various reagents known in the art depending upon the particular immunoassay format. For example, if uncomplexed antibody is to be detected, it can be complexed with a known quantity of labeled antigen. The amount of antibody can then be determined and correlated to the amount of unknown antigen in the original specimen.
The following examples are included to illustrate the practice of this invention, and are not meant to be limiting in any way. All percentages are by weight unless otherwise noted.
In all of the Figures, the bar graphs represent dye signals resulting from immunological reaction of the extracted antigen with the three antibody reagents present. For acceptable assays, the antigen should react only with its corresponding antibody, but if there is cross-reactivity due to non-specific binding c,f antigen to antibodies, unwanted dye signals will result.

~7~

MateriaL~ and ~e~hQ~s-for E~am~
SURECELL~ disposable test devices were used containing LOPRODYNE~ nylon microporous filtration membranes (1.2 ~meters average pore size) incorporated into the three test wells. The membrane was used without any further treatment.
A dye-providing composition A was prepared to include 4,5-bis(4-methoxyphenyl)-2 (3,5-dimethoxy-4-hydroxyphenyl)imidazole leuco dye (0.008%), poly(vinyl pyrrolidone) (1%), sodium phosphate buffer (10 mmolar, pH 6.8), hydrogen peroxide (10 mmolar), 4'-hydroxyacetanilide (0.5 mmolar) and diethylenetriaminepentaacetic acid (10 ~molar). Dye-providing composition B was the same but contained 5 mmolar 4'-hydroxyacetanilide.
The dye stop solution comprised sodium azide (0.1%) in phosphate buffered saline solution.
Various wash compositions were tried, as described below~
Polyclonal antibodies directed against each of the three microorganisms Actinob~cillus actinomyce~çmcom~ans, Baçteroide~s intermedi~s and Bacteroides qin~ivalis were prepared by intravenous injection of rabbits. IgG fractions were prepared by ammonium sulfate precipitation, and stored at 4C in phosphate buffered saline solution (0.3-0.4~ solution).
The bacterial strains used to produce the antisera were supplied as viable cultures by X.S. Reynolds (SUMY, Buffalo School of Dentistry). Isolates were subcultured on anaerobic plates. The microorganisms were those identified by the deposit numbers of ATCC
43717, ATCC 43718 and ATCC 43719 for Ac~in~ba~illu~
actinomycetemcomi~n~ ) (serotypes A, B and C, respectively), Arrcc 25611, NCTC 9336 and ATCC 43046 for Prevotella intermedia (P~i.) (serotypes A, B and C, respectively) and ATCC 33277, ATCC 53978 and ATCC 53977 ~7$~5~

for PorDhyromo~as ina~li$ ~P.g~) (serotypes ~, B and C, respectively). ATCC is the American Type Culture Collection in Rockville, Maryland, and the NCTC is the National Collection of Type Cultures in London, ;5 England.
Water-insoluble reagents were prepared by covalently binding the antibod:ies to polymeric particles (1 ~meter average diameter) of poly[st~rene-co-4-(2-chloroethylsulfonylmethyl)styrene] (95.5:4.5 molar ratio) which had been prepared using the procedures of EP-A-0 323 692. Covalent attachment was achieved by adding the antibodies to a solution of borate buffer (0.05 molar, pH 8.5) in a test tube and mixing well. The amount of A.a. used was 0.52 mg/ml (all serotypes) with each serotype being about 0.17 mg/ml. The amount of PLi and P.a~ used was about 0.75 mg/ml each, with each serotype of each microorganism being about 0.25 mg/ml. The polymeric particles (3%
solids) were added to the buffered mixture, and the resulting suspension was rotated end-over-end for 4 hours at room temperature to allow covalent attachment of the antibodies to the particles. The suspension was then centrifuged at 2800 rpm for 10 minutes. The supernatant was discarded and the pellet was suspended in glycine buffer (0.1%, pH 8.5) containing TWEENT~ 20 nonionic surfactant (0.1%, ICI Americas) and merthiolate (0.01%).
A coating suspension of the reagent described above (0.35% solids) was prepared to have polyacrylamide binder (5%), TWEENTM 20 nonionic surfactant ~0.1-~), merthiolate (0.01%) and W ITEXTM
optical brightener (0O0005%~ Ciba-Geigy) in glycine buffer (0.1 molar, pH 8.5). Each reagent directed to a distinct antigen was coated in defined regions of the membrane in the test devices described above.

2 ~ Q'; ~,, Enzyme-antibody conjugates were prepared using antibodies directed to each microorganism conjugated to horseradish peroxidase using the procedure of Yoshitake et al, ~u~.~.Bischem , lQ1, 395, :5 1979. Each conjugate composition comprised the conjugates (about 7.5-15 ~g of each per ml~ added to a solution of casein [0.5~, from a 1~ solution in 0.1 molar 3-(N-morpholino)propanesulfonic acid buffer, pH
7.5], TWEENTM 20 nonionic surfactant (0.3%~, merthiolate (0.01%) and 4~-hydroxyacetanilide (10 mmolar) in buffer (0.1 molar, pH 7.5). The solution was filtered through a 0.22 ~meter filter.
The composition for extracting antigen from the microorganisms comprised EMCOLTM CC-9 cationic surfactant (5%, Witco Corp.), sodium dodecyl sulfate (5%) in glycine buffer (0.1 molar, pH 8.5).
Various surfactants used in the comparisons of wash compositions below were as follows:
TERGITOL~4 alkylsodium sulfate anionic surfactant available from Union Carbide Corp.
EMPHOSTM CS1361 phosphate ester available from Witco Corp.
AVANELTM S-70 sodium alkyl ether sulfonate anionic surfactant available from PPG/Mazer.
DUPONOLT~ WAQE sodium lauryl sulfate anionic surfactant and ZONYLTM fluorochemical anionic surfactant available from E.I. DuPont de Nemours & Co.
ULTRAWET~ 60L linear alkylate sulfonate organic salt anionic surfactant available from ARCO.
MONAWETTM MM80 dihexyl sodium sulfosuccinate anionic surfactant available from Mona Industries.
SARKOSYL~ NL sodium lauryl sarcosinate anionic surfactant available from Ciba-Geigy Corp.
AEROSOL~ AY100 diamyl ester of sodium sulfosuccinic acid anionic surfactant available from American Cyanamide.

~7~

TRITON~ 770 sodium salt of an alkylarylpolyether sulfate anionic surfactant and TRITONT~ OS44 phosphate anionic surfactant available from Rohm and Haas.
HOSTAPALTM BV alkylarylpolyglycol ether sulfate, ;5 sodium salt anionic surfactant available from American Hoechst Corp.
POLYSTEPTM B12 sodium lauryl ether sulfate anionic surfactant available from Stepan Co.
SULFOBETAINETM DCH alkylammonium sulEonate, inner salt zwitterionic surfactant available from Textilana Corp.
All other reagents were obtained from Eastman Kodak Company or other well known suppliers of chemicals and reagents. 5 Example 1 Sandw ch Assay Usina Wa$h ~Qmposition ~f Iny~ iQ~
This example demonstrates the method of this invention to significantly reduce background in sandwich assays for microorganisms associated with periodontal diseases. It also shows the importance of the pH of the wash composition by comparisons with Control assays using wash compositions at about pH 7.
Wash CompQs tions:
The wash composition used in the method of this invention was composed of TERGITOLT~ 4 anionic surfactant (2.7%) in phosphate buffer (0.1 molar, pH
10). Control A assay was carried out using a solution of sodium decyl sulfate (1.8%) in sodium phosphate buffer (0.1 ~olar, pH 7.3) as the wash solution.
Control B assay was carried out using TERGITOLTM 4 anionic surfactant (2.7%) in phosphate buffer at pH
7.2.

2~786~

~ssay_Procedu~e:
This assay procedure was used generally in all of the examples of this specification with modifications being noted.
Antigen from ATCC 53978 [serotype B, P.~.]
was extracted by subjecting the cells to the extraction composition noted above for le,ss than one minute at room temperature to achie~e a final concentration of 1.25 x 108 total cells/ml.
The extract (~50 ~l)was filtered through a 1.2 ~meter membrane and added to one test well of the test device described above. The membrane of the test device had defined regions of reagents specific for each of A,a~, P,~. and P.i. Fluid was allowed to drain through the membrane in the test well. Antibody conjugate composition (80 ~l) was immediately added to each test well followed by incubation for two minutes at room temperature (about 20-25C). The wash solution (500 ~l) was then added to each test well and allowed to drain, followed by a second wash (500 ~l).
Dye-providing composition A (80 ~l) was added to each test well followed by a one minute incubation at room temperature. The dye signal was then visually evaluated and compared to a calibrated color chart containing reflectance density values. The reflection densities were then converted to transmission density (DT) using the Williams-Clapper transformation [see J.Q~tical Soc.~m., 43, p. 595 (1953)]. DT values of 0.003 or less correspond to a visual evaluation of ~no dye signaln.
The results were then tabulated as follows and plotted on bar graphs as shown in FIG. 1. It is clear that only the wash composition used according to the present invention effectively reduced the background from cross-reactivity of the P.gl antigen with antibodies specific to A.a~ and P.i. The 2V~8~
-~8-background was too high because some ~. antigen reacted non-specifically with ~ a. and ~_i~ antibodies in the Control assays. This example indicates that the wash compos1tion should have pH above about 9. -T A B L E
DT Vye Signal . . _ Assay _ P~9L Reagent ~ , Reayent A~ Reaq~
Control A 0.114 0.024 0.024 Control B 0.114 0.005 0.007 Example 1 0.101 0.003 0.003 Example 2 Com~arative Assays,at Hig,h_~H U$
Different Surfactant~
This Pxample is similar to Example 1 except that the wash compositions used in the assays were at pH 10.
The Control A assay was the same as in Example 1. The Control C assay used sodium decyl sulfate (1.8~) in phosphate buffer (0.1 molar, pH 10), whereas the Control D assay used sodium decyl sulfate (10%) in the same buffer. The Example 2 assay was the same as the Example 1 assay.
The results of the assays are shown below in Table II and graphically represented in FIG. 2. It is clear that only the assay of this invention provided detection o~ the antigen from P.a. without significant background from cross-reactivity o the antigen with antibodies specific to the other microorganisms. The Control assays demonstrated unacceptably high cross-reactivity and consequently high background. This indicates that besides pH, the wash composition must include certain surfactants.

2 0 ~

T A B ~ E II
DT Dye Signal Assay _ ~g~ Rea~ gg~t ~L_Rea~ent Control A 0.175 0.057 0.057 Control C 0.145 0.024 0.024 Control D 0.145 0.015 0.015 Example 2 0.145 0.003 0.003 Example 3 ComDarative assaYs ~iLsLçatiQni~
~nionic surfae~l5~ 4 h Compoqi~iQn$
This example is a comparison of several assays carried out by the protocol of Example 1 but using a variety of wash compositions.
The Control A and B assays were like those described above. Example 3 was like the Example 1 assay. The other Control assays utilized the following wash compositions:
Control E: EMCOL~M CC9 cationic surfactant (10%) in phosphate buffer (0.1 molar, pH 7.2).
Control F: EMCOLTM CC9 cationic surfactant (10%) in phosphate buffer (0.1 molar, pH 10).
Control G: TWEENTM 20 nonionic surfactant (10%) in phosphate buffer (0.1 molar, pH 7.2).
Control H: TWEENTM 20 nonionic surfactant (10%) in phosphate buffer (0.1 molar, pH 10).
Table III below shows the results of the assays, and the results are graphically represented in FIG. 3. It is apparent that only Example 3 demonstrates accurate detection of the extracted antigen (from P.g~) without significant cross-reactivity with the antibodies specific to the other microorganisms.

A B L E III
DT Dye Signal Assay ~g~_Reagent ~ Reagent_ Control A 0.114 0.024 0.024 Control B 0.114 0.005 0.007 Control E 0.180 0.057 0.073 Control F 0.175 0.022 0.022 Control G 0.175 0.057 0.073 Control H 0.175 0.027 0.057 Example 3 0.101 0.003 0.003 Examples 4 & 5 Comparisons of yarious ~.~h_~m~osilQn~
Con~ininq Anionic Surfaçtan~
These examples follow the assay protocol described in Example 1 and compare a number of wash compositions containing, primarily, anionic surfactants.
The anti~en determined was extracted from serotype C of P.~. The Example 4 and Control A assays were like those described in Example 1 except that Example 4 was in 3-cyclohexylamino-2-hydroxy-1-propanesulfonic acid buffer (0.1 molar, pH 10). The Example 5 assay used a wash composition comprising ULTRAWETTM 60L anionic surfactant ~5%) in the same buffer (0.1 molar, pH 10). All of the remaining control assays used wash compositions comprising the following surfactants in 3-cyclohexylamino-2-hydroxy-1 propanesulfonic acid buffer (0.1 molar, pH 10):
Control I: EMPHOSTM CS1361 anionic surfactant (5%).
Control J: AVANELTM S-70 anionic surfactant (5%)~
Control K: ethanolamine nonionic surfactant (3%).
Control L: DUPONOLTM WAQE anionic surfactant (5%).
Control M: ZONYLTM FSJ anionic surfactant (5%).
Control N: MONAWETTM MM80 anionic surfactant (5~).
Control O: SARKOSYL~M NL anionic surfactant (5%).

2~7~6~3 Control P: AEROSOLTM AY100 anionic surfactant (5%).
Control Q: TRITONTM 770 anionic surfactant (5%).
The assay results are shown in Table IV below .
;5 and graphically illustrated in FIG. 4. Only the assays of the present invention provided sensitive detection of the extracted antigen (from .P.glJ without significant cross-reactivity with the antibodies specific for the other microorganisms. The ~ackground signals shown in FIG. 4 are from signal not associated with antigen-antibody binding.

A B L E IV
DT Dye Signal , .
Assay _ P.q. Reagent ~1l~ Reagent Control A 0.185 0.073 0.073 Control I 0.185 0.073 0.073 Control J 0.185 0.101 0.101 Control K 0.185 0.114 0.114 Control L 0.185 0.042 0.042 Control M 0.185 0.057 0.057 Control N 0~185 0.027 0.027 Control O 0.185 0.101 0.101 Control P 0.185 0.101 0.101 Control Q 0.185 0.108 0.108 Example 4 0.185 0.015 0.015 Example 5 0.185 0.007 0.009 Examples 6-8 Further Com~arative ~ays ~sing ~ni~ni~
$urfac~ant.s These examples were carried out following the protocol described in Example 1 for all assays.
Control A was as described above. All wash compositions contained the noted surfactants in 3-2~7~5~

cyclohexylamino-2-hydroxyl-1-propanesulfonic acid buffer (0.1 molar, pH 10):
Example 6: ULTRAWETTM 60L anionic surfactant (5%).
Example 7: Mixture of ULTRAWETTM 60L anionic surfactant (5%) and TERGITOLTM 4 anionic surfactant (5%).
Example 8: TERGITOLTM 4 anionic surfactant (2.7%).
Control R: TRITONT~ QS44 anionic surfactant (5%).
Control S: HOSTAPALTM BV anionic surfactant (5%).
Control T: POLYSTEPTM B12 anionic surfactant (5%).
Control U: SULFOBETAINET~I zwitterionic surfactant (5%).
The results of the assays are shown in Table V below and illustrated in the bar graphs of FIG. 5.
It is apparent that only the assays of this invention provided the desired sensitivity to the extracted antigen from P~. with significantly reduced cross-reactivity to the antibodies specific to the other microorganisms. The background signal in FIG. 5 was from signal not associated with antigen-antibody binding.
T A B L E Y
DT Dye Signal Assay P._q. Rea~ent ~o Reagent _~ Reagent Control A 0.195 0.101 0.101 Control R 0.195 0.145 0.114 Control S 0.195 0.114 0.114 Contxol T 0.195 0.114 0.114 Control U 0.195 0.042 0.042 Example 6 0.175 0.013 0.013 Example 7 0.175 0.009 0.009 Example 8 0.175 0.011 0.011 2~6~

Example 9 ComDari_on of Simala~_ ~L~ an~ in wa sh Com~ositions This example compares three similar surfactants in wash compositions in assays carried out using the protocol of Example 1. TERGITOLTM 4 anionic ; surfactant (2.7%) in 3-cyclohexylamino-2-hydroxypropanesulfonic acid buffer (0.1 molar, pH 10) was used in the practice of this invention (Example 9), and was compared to the use of wash compositions containing TERGITOLTM 7 anionic surfactant (Control V, O.5%) and TERGITOLTM 8 anionic surfactant (Control W, 5%~ in glycine buffer (pH 10). At 5% concentration, TERGITOLTM 7 anionic surfactant did not flow through the membrane. It is generally an alkylsulfate having about 17 carbon atoms, and TERGITOLTM 8 anionic surfactant is generally an alkylsulfate having about 18 carbon atoms. Both are available from Union Carbide.
The results of the assays,are shown below in Table VI. It is clear that the similar surfactants do not provide the sensitivity and low cross reactivity desired and achieved using the wash composition containing TERGITOLTM 4 anionic surfactant.
T A B ~ E VI

DT Dye Si~nal . _ . _ . .
Assay ~ 5~ Reagent ~ Reagent ~ Reagent Control V 0.175 NA 0.019 Control W 0.175 0.024 0.025 Example 9 0.175 0.011 0.011 NA = Not Available Examples 10-16 Preferred Wash Com~09itlons a,nd AssaY~
Using ~,am~
A preferred wash composition of this invention includes casein mixed with TERGITOLTM 4 anionic surfactant in an appropriate buffer. The protocol of these assays was that as described in 2073~

Example 1. The following wash compositions of this invention were used:
Example 10: Surfactant (5%) only in succinic acid (0.1 molar, pH 5).
, 5 Example 11: Surfactant (5~) only in 2-(4~
morpholino)ethanesulfonic acid buffer (0.1 molar, pH

6).
Example 12: Surfactant (5!~) and casein (0.5%) in 2-(4-morpholino~ethanesulfonic acid buffer (0.1 molar, pH 6).
Example 13: Surfactant (5%) only in glycine buffer (0.1 molar, pH 9).
Example 14: Surfactant (5%) and casein (0.5%) in glycine buffer ~0.1 molar, pH 9).
Example 15: Surfactant (5~) only in glycine buffer (0.1 molar, pH 10).
Example 16: Surfactant (5%) and casein (0.5~) in glycine buffer (0.1 molar, pH 10).
The results of the assays are shown in the following Table VII and graphically illustrated in FIG.
6. The presence of casein seems to reduce cross-reactivity in assays using wash compositions that have pH closer to neutral. As the pH becomes more acidic (5 or below) or more basic (10 or above), the casein has 25 less effect. The background signal in FIG. 6 was from dye signal not associated with antigen-antibody binding.

~7~

A B ~ E VII
DT Dye Signal ~ .
Assay ~g__Reagent ~ Rea~ _t ~a~_~ea~ent ;Example 10 0.114 0.003 0.005 Example 11 0.130 0.023 0.024 Example 12 0.145 0.011 O.OlS
Example 13 0.175 0.024 0.024 Example 14 0.160 0.011 0.017 Example 15 0.160 0.003 0.003 Example 16 0.160 0.003 0.003 Example 17 Ass~y~ of ~he InventiQn~e~erminina ~ariQu~_~oncentrations Qf ~ntiqen, With and Withou~ Protein Pretream~n~
The present example illustrates the practice of this invention to determine various concentrations of antigen extracted from ~, E~g_ and P.~ The assay was carried out using the protocol described in Example 1 except that the solutions of extracted antigen were mixed with a composition containing AMIDEKTM protease (Genencor International, Rochester, N.Y.) (300 ~l of 20 mg/ml solution) for a few seconds at room temperature prior to adding the antigen to the test wells of the test devices. Dye-providing composition B was used in this example, and the concentration of antibody reagent was reduced 25% from that of Example 1. The coverage of antibody on the polymeric particles was 1.5 times that used in Example 1.
The wash composition comprised TERGITOLTM 4 anionic surfactant (1.35%), casein tO.5~) and thimerosal (0.1%) in glycine buffer (0.1 molar, pH 10).
The Control assay used a wash composition comprising sodium decyl sulfate (1.8%) in phosphate buffer (0.1 molar, pH 7.3).

207~

Antigen was extracted from P.g. serotypes A, B and C, P.i. serotype A and A.a~ serotype B. Antigen concentrations tested were 1.25 x 108 cells/ml, 1.56 x 107 cells/ml and 1.95 x 106 cells/ml for p.a- and Eli~
;5 and 6.25 x 107 cells/ml, 3.91 x 106 cells/ml and 4.88 x 105 cells/ml for ~
The results of the assays are tabulated in Table VIII. They illustrate the improved results obtained by using the method of this invention, and that the use of a protein pretreatment aids in the elimination of cross-reactivity particularly when high antigen concentrations are used.

2 0 ~

T A B L E VIII

Cell ~Q~ E~
Anti~en _ Concentration Assay Rea~ent Reaqent_ Reagent ~9~1.25 x 108Control 0.175 0.089 0.089 Serotype A cells/ml Exampl~e 17 0.175 0.007 0.011 ~g~1.56 x 107Control 0.101 0.019 0.019 Serotype A cells/ml Example 17 0.114 0.003 0.003 ~L 1.95 x 106Control 0.020 0.003 0.003 Serotype A cells~ml Example 17 0.019 0.003 0.003 ~g~1.25 x 108Control 0.185 0.101 0.101 Serotype C cells/ml Example 17 0.185 0.003 0.003 E~ 1.56 x 107Control 0.114 0.022 0.022 Serotype C cells/ml Example 17 0.160 0.003 0.003 ~9~1.95 x 106Control 0.025 0.003 0.003 Serotype C cells/ml Example 17 0.011 0.003 0.003 ~ 1.25 X 108Control 0.175 0.057 0.057 Serotype B cells/ml Example 17 0.195 0.003 0.003 ~9~1.56 x 107Control 0.101 0.007 0.007 Serotype B cells/ml Example 17 0.114 0.003 0.003 ~9~1.95 x 106Control 0.022 0.003 0.003 Serotype B cells/ml Example 17 0.024 0.003 0.003 ~ 1.25 x 108Control 0.022 0.195 0.022 Serotype A cells/ml Example 17 0.003 0.175 0.003 ~ 1.56 x 107Contxol 0.003 0.145 0.003 Serotype A cells/ml Example 17 0.003 0.114 0.003 ~ 1.95 x 106Control 0.003 0.054 0.003 Serotype A cells/ml Example 17 0.003 0.024 0.003 a~ 6.25 x 107Control 0.003 0.003 0.175 Serotype B cells/ml Example 17 0.003 0.003 0.175 al~3.91 x 106Control O.003 0.003 0.089 Serotype B cells/ml Example 17 0.003 0.003 0.101 ~ 4.88 x 105Control 0.003 0.003 0.007 Serotype B cells/ml Example 17 0.003 0.003 0.011

Claims (22)

1. An aqueous wash composition buffered to a pH of less than or equal to about 6 or greater than or equal to about 9, said composition comprising:
at least about 0.1 weight percent of an anionic surfactant which is represented by the formula:
[A-SO3+y]-(1+y) [X+m]n wherein A is a hydrocarbon having a molecular weight of at least about 180, x+m is hydrogen or a monovalent or divalent cation, m is 1 or 2, y is 0 or 1, and n is 1 or 2 provided that m and n are not both 2.

2. The composition of claim 1 buffered to a pH of from about 9.5 to about 11.

3. The composition of claim 1 comprising from about 1 to about 5 weight percent of said surfactant.

4. The composition of claim 1 further comprising a nonimmunoreactive protein.

5. The composition of claim 1 wherein said nonimmunoreactive protein is selected from the group consisting of: casein or another milk proteins, serum proteins and fibrinogen.

6. The composition of claim 1 wherein A is alkyl or alkyl-substituted phenyl having a molecular weight of from about 180 to about 250.

7. The composition of claim 6 wherein A is alkyl having from 14 to 16 carbon atoms, m and y are both 1, and n is 2.

8. The composition of claim 1 wherein A is tetradecyl, x+m is a sodium or potassium ion, and m and y are both 1.

9. A diagnostic test kit useful for the determination of a specific binding ligand, comprising, in individual packaging:
(1) an aqueous wash composition buffered to a pH
of less than or equal to about 6 or greater than or equal to about 9, said composition comprising:
at least about 0.1 weight percent of an anionic surfactant which is represented by the formula:

[A-SO3+y]-(1+y) [X+m]n wherein A is a hydrocarbon having a molecular weight of at least about 180, X+m is hydrogen or a monovalent or divalent cation, m is 1 or 2, y is 0 or 1, and n is 1 or 2 provided that m and n are not both 2, and (2) a receptor for a target specific binding ligand.

10. The kit of claim 9 wherein said receptor is either detectably labeled or immobilized on a particulate substrate, filtration membrane, cellulosic filter paper or polymeric or resin-coated film.

11. The kit of claim 10 wherein said receptor is labeled with an enzyme, and said kit further comprises a composition for providing a dye in the presence of said enzyme.

12. A method for the determination of a microorganism associated with periodontal disease comprising the steps of:
A. forming a water-insoluble complex of an antigen extracted from a microorganism associated with periodontal disease with an antibody specific for said antigen, B. separating uncomplexed materials from said water-insoluble complex by washing with an aqueous wash composition buffered to a pH of less than or equal to about 6 or greater than or equal to about 9, said composition comprising:
at least about 0.1 weight percent of an anionic surfactant which is represented by the formula:
[A-SO3+y]-(1+y) [X+m]n wherein A is a hydrocarbon having a molecular weight of at least about 180, x+m is hydrogen or a monovalent or divalent cation, m is 1 or 2, y is 0 or 1, and n is 1 or 2 provided that m and n are not both 2, and C. detecting the water-insoluble complex as a determination of said microorganism.

13. The method of claim 12 wherein said antigen is insolubilized by direct absorption or covalent attachment to a solid substrate, and detection is accomplished using either a detectably labeled antibody specific to said antigen, or an unlabeled first antibody specific to said antigen which is then complexed with a detectably labeled second antibody specific to said first antibody.

14. The method of claim 12 wherein detection of said water-insoluble complex is accomplished by detecting the resulting agglutinate of extracted antigen and said antibody which is affixed to small particles.

15. The method of claim 12 wherein said antibody is detectably labeled, and detection of said complex is accomplished by reaction of said antigen with a second antibody which is either immobilized or capable of being immobilized to form a water-insoluble sandwich complex of said antigen and both of said antibodies.

16. The method of claim 15 wherein said second antibody is attached to a polymeric particle having an average particle size of from about 0.01 to about 10 µmeters which are disposed on a microporous filtration membrane.

17. The method of claim 15 wherein said antigen is reacted with said second antibody prior to reaction with said detectably labeled antibody.

18. The method of claim 12 wherein said antibody is detectably labeled with an enzyme, and detection is accomplished by contacting said immobilized complex with a composition which provides a dye in the presence of said enzyme.

19. A method for the determination of a microorganism associated with periodontal disease comprising the steps of:
A. contacting an aqueous specimen suspected of containing an antigen extracted from a microorganism associated with periodontal disease with a microporous filtration membrane having thereon, in a discrete zone of a surface of said membrane, a water-insoluble reagent comprising water-insoluble particles having affixed thereto antibodies specific to said antigen, to form, in said zone, a water-insoluble complex between said antibody and said antigen, B. contacting said water-insoluble complex with a detectably labeled second antibody specific to said antigen to form a detectably labeled, water-insoluble sandwich complex in said zone, C. simultaneously or subsequently to step B, separating uncomplexed materials from said labeled, water-insoluble sandwich complex by washing said uncomplexed materials through said membrane with an aqueous wash composition buffered to a pH of less than or equal to about 6 or greater than or equal to about 9, said composition comprising at least about 0.1 weight percent of an anionic surfactant which is represented by the formula:
[A-SO3+y]-(1+y) [X+m]n wherein A is a hydrocarbon having a molecular weight of at least about 180, x+m is hydrogen or a monovalent or divalent cation, m is 1 or 2, y is 0 or 1, and n is 1 or 2 provided that m and n are not both 2, to separate uncomplexed materials from said labeled, water-insoluble sandwich complex, and D. detecting said labeled, water-insoluble sandwich complex as a determination of said microorganism in said specimen.

20. The method of claim 19 for the determination of any of Actinobacillus actinomycetemcomitans, Prevotella intermedius and Porphyromonas gingivalis.

21. The method of claim 19 for the simultaneous determination of a plurality of microorganisms associated with periodontal disease wherein said membrane has a plurality of distinct and independent zones containing distinct water-insoluble reagents for each of said microorganisms being determined.

22. An immunoassay for detecting the presence or amount of a water-insoluble complex formed from an antigen extracted from a microorganism associated with periodontal disease and an antibody specific to said antigen, comprising:
A. separating said water-insoluble complex from uncomplexed materials by washing with an aqueous wash composition buffered to a pH of less than or equal to about 6 or greater than or equal to about 9, said composition comprising at least about 0.1 weight percent of an anionic surfactant which is represented by the formula:
[A-SO3+y]-(1+y) [X+m]n wherein A is a hydrocarbon having a molecular weight of at least about 180, x+m is hydrogen or a monovalent or divalent cation, m is 1 or 2, y is 0 or 1, and n is 1 or 2 provided that m and n are not both 2, and B. detecting the separated water-insoluble complex or the uncomplexed materials washed from said complex.