SAP binds to the HA glycoprotein of IAV to mediate its antiviral activities.

<p>SAP was tested for its ability to mediate a range of anti-IAV activities against Ud/72, PR8, PR8-Ud/72 HA or PR8-Ud/72 NA. (<b>A</b>) Inhibition of virus-induced hemagglutination. Dilutions of SAP in TBS/Ca were tested for anti-IAV activity in standard HI assays. MIC values are the mean (±1 SD) concentration of SAP required to inhibit 4 HAU of virus. Dotted line indicates the maximum concentrated tested (5 µg/ml) and ‘+’ indicates a MIC value >5 µg/ml. (<b>B</b>) Inhibition of viral NA activity. Dilutions of virus were mixed with SAP (at a final concentration of 20 µg/ml or 2 µg/ml and assayed for NA activity. Results are expressed as the percent of NA activity compared to a virus only control. (<b>C</b>) Virus neutralisation. A dilution of each virus was mixed with SAP diluted in TBS/Ca to a final concentration of 20 µg/ml or 2 µg/ml and then incubated for 30 min at 37°C. The amount of infectious virus remaining was then determined by fluorescent-focus reduction assay. Results are expressed as a percent of the number of fluorescent foci in the virus only control. Data shown in A, B and C are the mean of three independent experiments (±1 SD). *p<0.05, ***p<0.001, One-way ANOVA, significantly different to viruses expressing Ud/72 HA (i.e. Ud/72 and PR8-Ud/72 HA).