Single dose of live-attenuated Zika vaccine found to protect mice

Research on the vaccine, which is currently in the development stage, was carried out by The University of Texas Medical Branch (UTMB) at Galveston, US and Brazil's Instituto Evandro Chagas.

The experimental Zika vaccine was made of the actual living Zika virus that was reduced in virulence, weakened until it became harmless.

According to the scientists, the live virus though weakened was able to cause strong immune response to provide potentially long-term protection from Zika virus infection.

UTMB’s Pei-Yong Shi said: “A successful vaccine requires a fine balance between efficacy and safety – vaccines made from attenuated live viruses generally offer fast and durable immunity, but sometimes with the trade-off of reduced safety, whereas inactivated and subunit viruses often provide enhanced safety but may require several doses initially and periodic boosters.

“Therefore, a safe live-attenuated vaccine will be ideal in prevention of Zika virus infection, especially in developing countries.”

For developing the experimental vaccine, the researchers could omit one segment of the viral genome for engineering the live Zika virus.

A similar process was successfully adopted to create a dengue virus vaccine that is being evaluated in phase three clinical studies, according to the researchers.

Shi added that the findings from the trial carried on mice demonstrated that the vaccine maintained a fine balance between safety and efficacy.

The vaccine candidate was also shown to have created strong responses in the immune system through a single immunization which provided permanent prevention to the mice from Zika virus.

Image: Single dose of a live-attenuated Zika vaccine protected mice from Zika virus. Photo: courtesy of The University of Texas Medical Branch at Galveston.