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

Vere Hodge, R Anthony

The efficacies of the 10-del ZIKA and 20-del ZIKA vaccines were compared in a study using rhesus macaques. There were four groups, a positive control with wt ZIKV administered on day 0 (n ¼ 4), active groups vaccinated (10 3 IFU sc) with 10-del ZIKA (n ¼ 4) and 20-del ZIKA (n ¼ 3) vaccines, respectively, and a placebo control (n ¼ 2). Viraemia was measured from day 2 to 10 and antibody levels from day 2 to 56. On day 56, all groups were challenged with ZIKV (PRVABC59, 10 3 PFU). Viraemia was measured from day 58 to 66 and antibody levels from day 70 to 98. As expected, the infected control group had high viraemia, high antibody levels from day 14 and had no viraemia after virus challenge. The placebo group had neither viraemia nor antibodies until after the virus challenge. Following vaccination with 10-del ZIKA vaccine, only 1/4 animals had detectable viraemia, 4/4 had moderate levels of antibodies which rose more than four-fold on virus challenge. In spite of the suboptimal levels of antibodies, no viraemia was detected after the virus challenge. In the 20-del ZIKA vaccine group, 2/3 had low levels of viraemia and 3/3 with high antibody levels from day 14 onwards. After virus challenge, there was minimal increase in antibody levels (0/ 4 with a four-fold rise) and there was no viraemia. Both deletion vaccines appeared to have a good safety profile.