Meeting report: 30th International Conference on Antiviral Research, in Atlanta, GA, USA

Vere Hodge, R Anthony

The vaccine efficacy was evaluated in male A129 mice. On day 0, one group were vaccinated (sc, 10 4 IFU) and two groups given placebo. On day 28, it was confirmed that all the vaccinated mice had high levels of antibodies but undetectable in the two placebo groups; that day, the vaccinated group and one of the placebo groups were challenged with ZIKV (strain from Puerto Rico, PRVABC59, 10 5 IFU). Viraemia on day 30 (two days after challenge) were high in the challenged-placebo group but undetectable in the other two groups. Tissues were harvested on day 49 (21 days after virus challenge). The virus levels in the testis tissue were high in the challenged-placebo group ($ 4 log 10 IFU/g) but undetectable in the other two groups. The sperm counts were low in the challenged-placebo group ($ 10 Â 10 6 /ml) but equally high ($ 20 Â 10 6 /ml) in the other two groups. The difference was even more marked when measuring motile sperm, being undetectable in the challenged-placebo group but equal (up to 10 Â 10 6 /ml) in the other two groups. In all these tests using male mice, the differences between the challenged-placebo group and the other two groups were highly significant but the results for the vaccinated group and the double-placebo (healthy mice) group were similar, the differences being not significant.