Selection and Characterization of a Neuraminidase-Minus Mutant of Influenza Virus and Its Rescue by Cloned Neuraminidase Genes

Genome packaging in influenza A virus

“…This segment-specific competition implied that packaging involved selection for distinctive features shared by the segment and its DI RNA. The terminal regions retained in DI RNAs included portions of the coding region as well as the UTRs (Davis et al, 1980;Duhaut & Dimmock, 1998, 2000Duhaut & McCauley, 1996;Hughes et al, 2000;Jennings et al, 1983;Liu & Air, 1993;Nayak & Sivasubramanian, 1983;Nayak et al, 1982;Noble & Dimmock, 1995) (see also Fig. 4).…”

“…Influenza A genome packaging deficient influenza viruses could be selected for in tissue culture using exogenously supplied bacterial neuraminidase and antibodies against the viral NA (Liu & Air, 1993;Yang et al, 1997). These viruses all retained internally deleted versions of segment 6, structurally akin to DI RNAs, strongly suggesting a positive selection pressure to retain the terminal regions of the vRNA (Yang et al, 1997).…”

“…Examples from every segment have been identified, but as yet, no sequence data have been reported for a segment 7 DI RNA (Davis et al, 1980;Davis & Nayak, 1979;Duhaut & Dimmock, 1998, 2000Duhaut & McCauley, 1996;Hughes et al, 2000;Jennings et al, 1983;Liu & Air, 1993;Nayak & Sivasubramanian, 1983;Nayak et al, 1982;Noble & Dimmock, 1995). The majority of DI RNAs studied have a single major internal deletion (Jennings et al, 1983;Nayak et al, 1982;Winter et al, 1981) and retain the terminal UTRs of their parent segment along with a variable amount of coding sequence (Davis et al, 1980;Davis & Nayak, 1979;Moss & Brownlee, 1981;Nakajima et al, 1979).…”

Efficacy and Safety of the Neuraminidase Inhibitor Zanamivir in the Treatment of Influenzavirus Infections

“…3,4 This enzyme, essential for replication in vitro, 5 cleaves terminal sialic acid residues from glycoconjugates to allow the release of virus from infected cells, prevent the aggregation of virus, and possibly reduce viral inactivation by respiratory mucus. 6,7 Zanamivir inhibits a range of influenza A and B viruses in vitro.…”

Biosynthesis, intracellular transport and enzymatic activity of an avian influenza A virus neuraminidase: role of unpaired cysteines and individual oligosaccharides.

“…Late in infection, it has been shown to permit release of progeny virus particles from the host cell and to prevent aggregation (Palese et al, 1974). This concept was further supported by the observation that an NA-minus mutant of influenza virus is still infectious but produces progeny virus only in the presence of exogenously added bacterial NA (Liu & Air, 1993). Furthermore, removal of terminal neuraminic acid by viral NA is important for full receptor binding and fusion activity of haemagglutinin (HA) (Ohuchi et al, 1995).…”