The disclosure relates to avian influenza vaccines produced through reverse genetics to protect from A/Turkey/Indiana/22-like virus, methods for producing such vaccines, and method for using such vaccines to protect poultry. The disclosure also relates to methods of producing influenza viruses comprising chimeric polynucleotides having an HA non-coding sequence from an apathogenic high growth influenza virus and a polynucleotide encoding an HA protein from a highly pathogenic avian influenza virus or variant thereof, and/or having a chimeric polynucleotide having an NA non-coding sequence from an apathogenic high growth influenza virus and a polynucleotide encoding an NA protein from a highly pathogenic avian influenza virus or variant thereof.

A method for adapting an influenza virus to Vero cells is provided. The method comprises infecting Vero cells with the influenza virus, cultivating the infected Vero cells, harvesting influenza viruses of each passage, wherein infectious dose of the influenza viruses of one passage is greater than or equal to infectious dose of the influenza viruses of a previous passage. The present disclosure also relates to a composition. Said composition comprises polyriboinosinic acid-polyribocytidylic acid, at least one antibiotic or polyamide compound, at least one positive ion, influenza viruses and/or influenza antigens, wherein said influenza viruses and/or influenza antigens are acquired from Vero cell adapted influenza viruses.

Mutation of adenosine methylation sites in nucleic acids encoding influenza virus hemagglutinin are provided that result in increases in vRNA, mRNA, and protein expression over time and increases in infectious titers when produced in mammalian cells.

The present disclosure discloses a whole avian-origin reverse genetic system, a recombinant H5N2 subtype avian influenza virus, a vaccine containing the virus, and a preparation method and application thereof. The genome of the recombinant virus is comprised of a modified HA gene derived from a highly pathogenic H5N6 subtype avian influenza virus strain, as well as PB2, PB1, PA, NP, NA, M and NS genes derived from H5N2 subtype avian influenza D7 virus strain. The recombinant virus is a recombinant H5N2 avian influenza virus rescued from the D7 virus strain as a backbone, which is an avirulent virus strain with the original immunogenicity, and can maintain a high virus titer during the chick embryo culture process. The recombinant virus fully meets the biological safety requirements and has a good application prospect.

Provided are compounds that enhance the efficacy of viruses by increasing spread of the virus in cells, increasing the titer of virus in cells, or increasing the antigen expression from a virus, gene or trans-gene expression from a virus, or virus protein expression in cells. Other uses, compositions and methods of using same are also provided.

The present invention provides, among other things, a novel and improved method for generating “mosaic” influenza antigenic polypeptides including hemagglutinin (HA) and neuraminidase (NA) polypeptides based on unique combination of epitope patterns that maximize exposure to epitopes present across multiple HA or NA sequences and therefore improved influenza strain coverage. In particular, the present invention provides engineered H1N1 influenza hemagglutinin (HA) polypeptides that are comprised of novel combinations of protective epitopes and antigenic regions from multiple H1N1 viral strains. Such engineered HA polypeptides have improved properties over HA polypeptides developed through conventional approaches that rely on consensus alignments of viral sequences.

The invention provides an influenza virus that demonstrates enhanced growth in Vero cells. The influenza virus includes PB1, PB2, PA, NP, and NS gene segments encoding proteins having amino acid sequences with selected amino acids. Optionally, at least one of the PB1, PB2, and PA gene segments includes a cytosine to uracil promoter mutation at nucleotide position 4. The invention el also provides a pharmaceutical formulation containing the influenza virus, as well as a method of eliciting an immune response in a mammal by administering the influenza virus to the mammal, and a method for generating the influenza virus.

An isolated recombinant influenza virus is provided having PA, PB1, PB2, NP, NS, M, NA and HA viral segments, wherein the PB1 viral segment encodes a PB1 with a residue other than isoleucine at position 711 or the M viral segment encodes a M1 with a residue other than methionine at position 128, wherein the recombinant influenza virus has enhanced replication relative to a corresponding influenza virus having a PB1 viral segment that encodes a PB1 with an isoleucine at position 711 or having a M viral segment that encodes a M1 with methionine at position 128, as well as methods of making and using the virus.

The present invention relates to methods of replicating viruses in vitro. In particular, the invention relates to a genetically modified population of cells, and/or a population of cells treated with an exogenous compound, wherein the cells are capable of producing more virus than cells lacking the genetic modification and/or lacking treatment with the exogenous compound. The invention also relates to methods of producing populations of such cells, as well as the use of the viruses obtained to prepare vaccine compositions.

A heat-resistant H1N1 subtype influenza virus mutant strain rPR8-HA-N5 has been preserved at China Center for Type Culture Collection, Wuhan University, Wuhan, China with the preservation number of CCTCC No. V202043.