Rewiring the RNAs of influenza virus to prevent reassortment

Influenza A virus-generated small RNAs regulate the switch from transcription to replication

“…Because efficient influenza A virus egress requires RNP association (45), the near total loss of HA, NP, and NS1 in the target MDCK cells suggests a defect in packaging, possibly because of the loss of HA vRNA. This possibility is supported further by the fact that HA vRNA packaging sequences are essential components required for viral egress (46).…”

Genome packaging in influenza A virus

“…4c), and in every case, the terminal coding regions, comprising sequences unique for each segment, have been found to promote more efficient packaging than the UTRs alone (Dos Santos Afonso et al, 2005;Fujii et al, 2003;Fujii et al, 2005;Gog et al, 2007;Liang et al, 2005Liang et al, , 2008Marsh et al, 2007;Muramoto et al, 2006;Ozawa et al, 2007Ozawa et al, , 2009Watanabe et al, 2003). The observation that virus formation is inefficient in the absence of the terminal regions of all eight vRNAs has also been corroborated and extended by examining the effects of removing other segments (de Wit et al, 2006;Fujii et al, 2009;Gao et al, 2008;Gao & Palese, 2009;Marsh et al, 2007).…”

“…We speculate that the fact that the first nine codons of the M2e coding region also overlap the segment 7 packaging signal (Gog et al, 2007;Hutchinson et al, 2008;Ozawa et al, 2009) will further constrain the development of escape mutants. Better understanding of influenza virus genome packaging has also facilitated attempts to use the virus as a gene delivery vector (Gao et al, 2008;Shinya et al, 2004) as well as providing an ingenious approach to improving engineered virus biosafety through reducing the probability of successful reassortment with 'wild' viruses (Gao & Palese, 2009). …”

Influenza Viruses with Rearranged Genomes as Live-Attenuated Vaccines

“…Because the H5 HA is expressed from the H9N2-H5 virus as a chimeric HA segment with the packaging signals of the NS gene, the possibility of reassortment of the H5 HA is remote (25). Nevertheless, genetic reassortment could take place if a circulating IAV exchanged both RNA segments 2 and 8 with the rearranged IAV.…”