Super-infection up to 12 h after primary infection leads to robust reassortment in vivo.

1Quantitative PCR was performed using primers specific for wild-type or var virus HA segments. Average of two replicates is shown. Ct values <35 were considered indicative of productive infection. 2n = 19–22 virus isolates from each guinea pig. 3The proportion of wt and var viruses present in the inoculum for the 0 h group was 61% and 39%, respectively (n = 25). 4wt and var6 controls are nasal washes collected from guinea pigs singly infected with each virus.