Abstract: The invention relates to a simple and efficient process for isolating viruses from various sources and for producing live attenuated influenza vaccines in a serum-free Vero cell culture under conditions where alterations in the surface antigens of the virus due to adpative selection are minimized or prevented. The process does not require purification of the virus-containing supernatant harvested from the cell culture nor post-incubation treatment of the viruses for HA activation. The invention further relates to influenza A and B master strain candidates and to vaccines made thereof.

Abstract: 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 remaining portion of the NS1 gene segment. It further relates to embodiments, wherein the modification comprises deletions, insertions, or a shift of the open reading frame, and particularly to constructs comprising an insertion of an autocleavage site 2A, the nef gene from HIV-1 or the sequence encoding the ELDKWA-epitope of gp4l of HIV-1. The invention also relates to influenza virus transfectants that contain the modified NS gene and have an IFN inducing phenotype but which may or may not be sensitive towards IFN. The invention also relates to vaccines comprising such a chimeric virus.

Abstract: The invention relates to a simple and efficient process for isolating viruses from various sources and for producing live attenuated influenza vaccines in a serum-free Vero cell culture under conditions where alterations in the surface antigens of the virus due to adpative selection are minimized or prevented. The process does not require purification of the virus-containing supernatant harvested from the cell culture nor post-incubation treatment of the viruses for HA activation. The invention further relates to influenza A and B master strain candidates and to vaccines made thereof.

Abstract: 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 remaining portion of the NS1 gene segment. It further relates to embodiments, wherein the modification comprises deletions, insertions, or a shift of the open reading frame, and particularly to constructs comprising an insertion of an autocleavage site 2A, the nef gene from HIV-1 or the sequence encoding the ELDKWA-epitope of gp4l of HIV-1. The invention also relates to influenza virus transfectants that contain the modified NS gene and have an IFN inducing phenotype but which may or may not be sensitive towards IFN. The invention also relates to vaccines comprising such a chimeric virus.