The invention relates to a recombinant NS gene of an influenza A virus comprising a functional RNA binding domain and a gene sequence modification after nucleotide position 400 of the NS1 gene segment, counted on the basis of influenza A/PR/8/34 Virus, wherein the modification bars transcription of the...http://www.google.es/patents/US6800288?utm_source=gb-gplus-sharePatente US6800288 - Recombinant influenza A viruses
