The effect of influenza B virus M segment on the replication of reassortant vaccine viruses
Flumist™ is a cold-adapted (ca), live attenuated influenza virus vaccine containing H1N1, H3N2, and B strains. The vaccine strains have a 6:2 gene constellation. Six gene segments, PB1, PB2, PA, NP, M and NS, are derived from the master donor viruses, ca A/Ann Arbor/6/60(MDV-A) and ca B/Ann Arbor/1/66(MDV-B), and two gene segments, the hemagglutinin (HA) and neuraminidase (NA), are derived from circulating wild-type strains. We observed that the M gene segment of influenza B virus reassortants can influence the replication of these viruses in CEK cells. Replication curves revealed that a 6:2 reassortant B virus (wt HA and wt NA) replicated less well, by approximately 2 log10, than the corresponding 5:3 strain (wt HA, wt NA and wt M) at 33 °C in chicken embryo kidney (CEK) cells; this difference was not observed at 25 °C. © 2004, Elsevier B.V.
Chen, Z; Du, J; Hoffmann, E; Spaete, J; Kemble, G
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