Preclinical efficacy of a live vesicular stomatitis virus-based Lassa virus vaccine candidate advanced for human clinical trials

We advanced a promising experimental vaccine for immunizing against the Lassa virus surface glycoprotein as a candidate for human trials. Preclinical evaluation of the vaccine candidate based on a live vesicular stomatitis virus (VSV) vector showed that it was highly efficacious in cynomolgus macaques consistent with earlier research studies, and that the animals developed serum antibodies that could mediate antiviral effector functions including direct neutralization of virus infectivity. As part of this evaluation, we analyzed whole-blood transcriptomes from each study subject prior to vaccination and at 1 day and 3 days post-vaccination. Ten Chinese-origin cynomolgus macaques (Macaca fascicularis) were assigned to two vaccine groups of five animals each. Each group of vaccinated animals was composed of two males and three females. One group was administered a single dose of 2x10^7 PFU VSV∆G-LASV-GPC, the other group received a lower dose of 2x10^5 PFU, both by intramuscular (IM) injection. Animals were vaccinated once with 1 ml of virus injected into the caudal thigh. A control group of three animals (one female and two males) received an equivalent volume of vaccine diluent (PBS, 5% trehalose) delivered IM.