FIG 6.
Time to transmission is lower for human and canine versus swine IAVs and typically decreases with inoculation dose. The average time to first detection of infectious virus in nasal washes of exposed guinea pigs is plotted, with standard error. (A) Two-way ANOVA with Tukey’s correction for multiple comparisons was used to evaluate significance of differences among virus strains. Only data from doses of 1 × 102 and 1 × 103 PFU were included in this analysis. Differences among NL/09, Pan/99, and can/IL/15 were not significant. Differences between sw/Sp/04 and sw/KS/07 were not significant. * indicates significant difference relative to NL/09 (P < 0.01); # indicates significant difference relative to Pan/99 (P < 0.01). (B) All doses tested were analyzed by linear regression. Slopes were significantly nonzero for NL/09 (P = 0.0040), Pan/99 (P = 0.0014), and sw/KS/07 (P < 0.0002) viruses.