ZIka Update: Two New Zika Vaccine Effective in Mouse Models

Two new vaccines against Zika virus have proven its effectiveness in preclinical trials involving mice challenged with Zika virus, suggesting that Zika vaccines for humans are still achievable.

Their findings, published in the journal Nature, showed that the two experimental vaccines have protected mice from ZIka virus four to eight weeks after receiving the initial injections.

The first vaccine called DNA vaccine contains genetic snippets from a Zika virus strain that circulated recently in Brazil to elicit immune responses, while the second vaccine, dubbed as inactivated virus vaccine, is made from a purified, inactivated Zika virus that recently circulated in Puerto Rico.

For the study, researchers exposed mice that are injected with either of the two vaccines to the Brazilian strain of Zika virus four weeks after their initial inoculations. The researchers then discovered that no viral replications can be detected in the vaccinated mice. Both vaccines provide protection against the Zika virus. Additionally, the researchers noted that the levels of Zika-specific antibody detected in the immunized mice appeared to correlate with protection against infection.

Also, mice injected with the DNA vaccine and were exposed to the ZIka virus eight weeks after the immunization were also protected from the virus.

Both the DNA vaccine and inactivated virus vaccine were developed to protect against flaviviruses, a family of viruses that includes Japanese encephalitis, dengue, West Nile and Zika viruses.

"Taken together, our findings provide substantial optimism that the development of a safe and effective Zika vaccine for humans will likely be feasible," researchers wrote in a statement.

The DNA vaccine was developed by the through the joint efforts of Beth Israel Deaconess Medical Center (BIDMC), Harvard Medical School, Ragon Institute of MGH, MIT and Harvard. On the other hand the inactivated virus vaccine was developed by researchers at Walter Reed Army Institute of Research, Silver Spring, Maryland.

According to a press release, the researchers are now planning to conduct a human trial of the two potential vaccines in the United States in partnership with National Institute of Allergy and Infectious Diseases (NIAID), through its Vaccine and Treatment Evaluation Units.