FIG 9.

In-contact transmission of P9 virus-derived L2, N9, and L18 viruses in guinea pigs. Four groups of guinea pigs (three to a group) each were intranasally inoculated with 10⁶ TCID₅₀ of L2 (A), N9 (B), L18 (C), or rHIN1 (D) virus. At 1 dpi, each directly infected animal (individually housed) was moved to another cage holding a naive guinea pig. Viral titers of daily nasal washes were determined by TCID₅₀ assays on MDCK cells from the directly infected (squares with dotted lines) and in-contact guinea pigs (triangles with solid lines) and are presented as a function of days postvirus inoculation. Two out of three in-contact guinea pigs for each P9-derived virus showed virus shedding. There was no detectable rH1N1 virus shedding from in-contact guinea pigs. The virus detection limit was 10 TCID₅₀.