FIG 4.

Neuraminidase inhibition activity and viral lung titers in mice. (A) ELISA reactivity of selected groups to N9 NA. (B) N9 NI titers of groups shown in panel C. NI was measured by using A/Shanghai/1/13 virus; values are expressed as the reciprocal serum dilution that was able to inhibit NA activity by 50%. (C to E) Lung titers of mice vaccinated with different vaccination regimens on day 3 (black) and day 6 (red) postinfection. Samples with no detectible virus titer were scored as 10. The naive day 3 and day 6 groups were included in all three panels to facilitate comparison with the vaccine groups. ND, not determined.