FIG. 3.

Blockade of HN site I by zanamivir restores viral titers for all variants except HN-H552Q: impact of enhanced receptor avidity and F triggering. HAE cultures were infected with wt HPIV3 or with the HN T193A, H552Q, or N551D variant. Zanamivir was added via the apical surface 30 min prior to the collection of the supernatant fluid, and viral titers (y axis) were determined by plaque assay and compared to values for mock-treated cultures. The bars show the results at day 3 after infection. Data points are means (± standard deviations) of triplicate measurements and are representative of data from three to five experiments.