Dysregulation of M segment gene expression contributes to influenza A virus host restriction
Fig 15
Reduced expression of avian M2 improves replication efficiency in vivo but is not sufficient for efficient transmission in guinea pigs.
Groups of twelve guinea pigs were inoculated with 10 PFU of PR8-based viruses carrying avian M, NL09 M, chimeric NL09 M 7mut M, or chimeric avian M 9mut segments, as indicated. (A) Virus replication in nasal washings was measured by plaque titration at days 2, 4, 6, and 8 post-infection and the total area under the curve was calculated. The replication differences between viruses with NL09 M and NL09 M 7mutAv segments were not significant (P = 0.720). Differences between viruses encoding the NL09 M 7mut segment and the avian M 9mut segment trended towards, but were not statistically significant (P = 0.115). (B) Transmission to naïve cage mates that were exposed at 24 hpi. Neither chimeric M segment conferred efficient transmission (7/9 transmissions; 78%). Statistical significance of replication differences was determined using a two-tailed Student’s t-test. Statistical significance of transmission differences was determined using an unpaired two-tailed Student’s t-test. NL M and avian M data are identical to data presented in Fig 3 and are reproduced here for clarity.