A vaccine based on the Zika virus NS1 protein was shown to give single-dose protection against the virus in an immunocompetent lethal mouse challenge model, according to a recent study presented by Farshad Guirakhoo, chief scientific officer of GeoVax, Inc.
Guirakhoo presented his findings at the June 4 conference of the American Society for Microbiology (ASM) in New Orleans.
According to ASM, the viral vector vaccine technology developed by GeoVax uses a highly-potent, safe, and replication-deficient viral vector to express vaccine antigens in the recipient’s cells. The technology has previously been used to develop vaccines candidates for both the Ebola virus and HIV.
The study involved infecting outbred immunocompetent mice with a lethal dose of the virus directly into their brains. Guirakhoo stated that a single dose of the GeoVax vaccine candidate protected 100 percent of mice subjects from the lethal effects of the virus. In the control group, between 80 and 90 percent of the subjects died within 7-10 days.
NS1 was chosen as the vaccine’s target immunogen to avoid potential risks of disease enhancement when vaccines are developed based on Zika envelope proteins. This effect, called antibody dependent enhancement of infection, was seen in developing vaccines for other flaviviruses such as Dengue fever, in both in vitro and in vivo studies.
ASM said an NS1-based vaccine could also limit or block the transmission of Zika in its mosquito vector.
Zika virus is typically transmitted by the Aedes aegpyti species mosquito and sexual contact. Symptoms in most cases involve joint pain, fever, rash, and headaches. More severely, the virus has been linked to microcephaly of the fetus in pregnant women and Guillain-Barré syndrome.