A Seven-Segmented Influenza A Virus Expressing the Influenza C Virus Glycoprotein HEF

Genome packaging in influenza A virus

“…Similarly, mutations in the segment 7 packaging signals reduced incorporation of each of the eight segments by an approximately equal extent, such that the majority of virions contained an incomplete genome (Hutchinson et al, 2008). Lesions in segment 7 also reduced virus budding (Hutchinson et al, 2008), consistent with the prior data inferred from examining VLPs and viruses with less than eight segments (de Wit et al, 2006;Fujii et al, 2005;Fujii et al, 2009;Gao et al, 2008;Marsh et al, 2007;Ozawa et al, 2009). More specific secondary effects on segment incorporation after mutation of a single packaging signal have also been seen.…”

“…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). …”

Rewiring the RNAs of influenza virus to prevent reassortment

“…In this study, we attempted to change the packaging signals of the HA and NS segments of influenza A/PR/8/34 virus to prevent free reassortment of these RNAs. It was shown earlier that foreign genes can be packaged into influenza viruses by adding flanking packaging sequences (8,(12)(13)(14)(15). For example, a green fluorescent protein (GFP) segment was incorporated into influenza virus particles using the packaging signals of the neuraminidase segment (15).…”

“…However, what is currently known about these packaging sequences can be used to incorporate foreign genes into the virus genome. This adds an approach for the development of influenza virus as a bivalent vaccine or gene delivery vector (8,(12)(13)(14)(15).…”