A recombinant vesicular stomatitis virus Ebola vaccine

An experimental vaccine against Ebola virus disease (EVD) is showing promise, based on evidence from a pair of early studies funded in part by NIH. The Phase I trials focused on a recombinant vesicular stomatis virus (rVSV)-based candidate vaccine expressing the glycoprotein of a Zaire strain of Ebola (ZEBOV).

An experimental vaccine against Ebola virus disease (EVD) is showing promise, based on evidence from a pair of early studies funded in part by NIH. The Phase I trials focused on a recombinant vesicular stomatis virus (rVSV)-based candidate vaccine expressing the glycoprotein of a Zaire strain of Ebola (ZEBOV). Each study enrolled 39 adults, who were given either a placebo or the vaccine at a dose of 3 million plaque-forming units (PFU), 20 million PFU, or 100 million PFU. The test vaccine elicited antibody responses against EVD, with all recipients achieving seroconversion by day 28. A second dose at 28 days, administered at one of the two study locations, significantly increased antibody titers at day 56. While many vaccine recipients experienced rVSV viremia, it was transient in nature; and adverse events were largely limited to injection-site pain, fatigue, myalgia, and headache. Antibody activity against ZEBOV glycoprotein was greater in participants receiving 20 million PFU or 100 million PFU than in those who received 3 million PFU, but there was no significant difference between the group receiving a dose of 20 million PFU and the group receiving a dose of 100 million PFU. "These results support further evaluation of the vaccine dose of 20 million PFU for preexposure prophylaxis and suggest that a second dose may boost antibody responses," the authors conclude.