Zika Virus Vaccine Clinical Trials Might Commence Later this Year

As Zika virus is constantly spread around the world, the race is on to develop a vaccine towards the virus. Now, like a feat may be in sight; investigators have finished a second round of preclinical studies of a Zika vaccine, and outcomes show it provided complete protection against the virus in monkeys.

Study Co-lead author Col. Nelson Michael and colleagues presented their results in the journal ‘Science’.

Zika is a virus belonging to the genus flavivirus, and it is most frequently spread via the bites of infected Aedes  aegypti and Aedes  albopictus mosquitoes.

With respect to the World Health Organization (WHO), as of July 27, 2016, 50 nations and territories throughout the world have reported a 1st outbreak of mosquito borne Zika virus transmission since previous year.

The U.S. is the very latest nation added to the list; last week, the Centers for Disease Control and Prevention (CDC) confirmed mosquito-borne transmission of the virus in Wynwood.

Symptoms of Zika may contain conjunctivitis, fever, headache, joint pain, muscle pain and rash. However many individuals infected with the virus experience no symptoms at all. If symptoms do occur, they generally only last for approximately 1 week and rarely warrant a hospital visit.

For pregnant women and their babies, however, Zika can have extremely serious effects.

Zika and microcephaly

Since the Zika outbreak in Brazil in May 2015, the nation experienced an increase in cases of microcephaly – a birth defect in which a baby is born with a smaller than usual head.

Additional investigation proved that Zika infection is a trigger of microcephaly, and as an outcome, the WHO announced this connection a Public Health Emergency of International Issue in February 2016.

At the moment, there is no vaccine for Zika; the only methods to decrease risk of infection are to stay away from traveling to contaminated areas, avoid mosquito bites, and to use condoms while in sexual intercourse, which can decrease sexual transmission of the virus.

But the new research provides hope, after unveiling the development of a vaccine known as ZIKV purified inactivated virus (ZPIV) that has so far provided full protection towards two strains of Zika virus in monkeys.

Vaccine completely protected against Brazilian, Puerto Rican Zika strains

Earlier research from Col. Michael and colleagues confirmed high efficiency of the ZPIV vaccine – which was developed by WRAIR investigators – in mice infected with Zika virus.

The new research develops those results, indicating efficacy in nonhuman primates, whose immune system reactions to vaccines more closely look like those of humans.

For this recent research, the study team administered the vaccine to rhesus macaque monkeys.

In the 2 weeks following their initial vaccination, the monkeys demonstrated binding and neutralizing antibodies for the virus, and levels of these antibodies enhanced even more with a second vaccine dose administered at 4 weeks.

The investigators then infected the monkeys with the Zika virus. On examining the blood, urine, and other secretions from the nonhuman primates, the team could discover no detectable Brazilian or Puerto Rican Zika strains, which means the vaccine provided complete protection towards the virus.

In addition, the ZPIV vaccine did not result in any adverse effects in the monkeys.

Depending on these and earlier outcomes, the team considers the ZPIV vaccine will enter phase I clinical studies later this year.

“Outcomes from both mouse and nonhuman primate evaluating are motivating and support a choice to move ahead with our U.S. government, industry and regulatory authorities to progress our ZPIV vaccine candidate to clinical trials.

It builds on technology WRAIR developed and efficiently utilized to other flavivirus vaccines. We wish that by leveraging a proven technology we raise our chances of establishing a safe and effective Zika vaccine.”

Col. Stephen Thomas, WRAIR

Col. Michael hails WRAIR’s collaboration with investigators from Harvard Medical School and the Beth Israel Deaconess Medical Center – both in Boston, MA – for the rapid completion of animal trials for ZPIV.

“We will make use of WRAIR’s research capabilities and expertise in flavivirus countermeasures to quickly develop a successful Zika virus vaccine working with our academic and government associates.”