ASM Microbe: NS1-based Zika vaccine demonstrates promise in mice

Research presented at the American Society for Microbiology Microbe 2017 conference (1–5 June, LA, USA) has reported a novel Zika vaccine, which can induce 100% protection in mice after a single dose. This is the first vaccine to be based on the Zika virus non-structural protein 1 (NS1).

The team hope that by utilizing NS1, an antigen not presented on the viral surface, the vaccine will avoid the risks of antibody dependent enhancement, a phenomenon that has been observed in Zika virus and the related-flavivirus dengue.

This vaccine constitutes a vector, the Modified Vaccinia Ankara virus, engineered to display Zika antigens in order to induce an immune response. The vector technology was developed by Geovax Inc. (GA, USA) and has previously been utilized in vaccine candidates for HIV and Ebola.

The findings, from a study funded by the Centers for Disease Control and Prevention (GA, USA), report results from mice receiving either the NS1 vaccine or a sham immunization before being exposed to lethal doses of Zika virus delivered to the brain. The researchers demonstrated that a single dose of Geovax’s NS1 vaccine candidate protected 100% of vaccinated animals. Compared with this, the team observed that 80–90% of the control group died 7–10 days after the Zika challenge was administered.

In addition to showing promise for inducing protective immunity, the researchers also hope an NS1-based vaccine may limit the transmission of Zika virus via its mosquito vector. NS1 normally interferes with the mosquito’s innate immune system, allowing Zika to replicate and disseminate in the insect, therefore interrupting this pathway could block transmission of the virus.

Chief Scientific Officer of GeoVax, Farshad Guirakhoo, concluded: “A vaccine that can induce effective antibodies to NS1 and disable its function has the potential to reduce growth and transmission of Zika virus in its mosquito vector. This could enhance vaccine effectiveness in endemic areas by blocking the virus transmission from infected individuals to other members of the community.”



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