Fig 3.
In vitro and in vivo characterization of PB1SP and PASP viruses reveals a significant attenuation. (A and B) The replication kinetics of the SP viruses was evaluated in three independent experiments in single (MOI, 1) (A) and multicycle (MOI, 0.01) (B) replication assays in MDCK cells. Error bars represent standard errors. Supernatants were harvested at the indicated time points postinfection, and titers were determined by plaque assays. (C and D) The ability of these viruses to cause disease was evaluated in BALB/c mice (n = 10 per group) infected with several doses of each SP or PR8 virus.