Zika Vaccine Candidate Shows Promise in Monkeys and Mice

A team of investigators at the University of Hawaii's John A. Burns School of Medicine in Honolulu have developed a promising vaccine candidate for Zika virus that is proving effective in preclinical trials in monkeys and mice.

The research, published in Frontiers in Immunology, details the efficacy of the team’s recombinant subunit vaccine, which comprises only a small part of a protein from the Zika virus produced in insect cells.

Led by 2 senior graduate students as lead authors of the study, and supervised by Axel Lehrer, MD, an assistant professor of tropical medicine and infectious disease at the John A. Burns School of Medicine, the team of investigators “demonstrate[d] the efficacy of [their] recombinant subunits in a non-human primate viremia model.”

“High neutralizing antibody titers were seen in all protected macaques and passive transfer demonstrated that plasma from these non-human primates was sufficient to protect against viremia in mice subsequently infected with Zika virus,” investigators reported. “Taken together our data demonstrate the immunogenicity and protective efficacy of the recombinant subunit vaccine candidate in non-human primates as well as highlight the importance of neutralizing antibodies in protection against Zika virus infection and their potential implication as a correlate of protection.”

The Zika virus has been at the forefront of the public health consciousness since the epidemic in French Polynesia in 2013-2014 and the subsequent outbreaks in Brazil in 2015-2016. There is currently no vaccine approved for Zika virus—which can be transmitted via infected mosquitos, sex, and from mother to child—although there are several currently in clinical trials.

"The intense search for a Zika remedy since early 2016 has required us to be agile, and we believe our vaccine candidate research demonstrates that such quick-turnaround results can be achieved in academic and scientific partnerships here in Hawaii," Dr. Lehrer said in the press release. "It is incredibly gratifying that two of the scientists we are training to be the future of biomedical science played key roles in gathering, analyzing, and reporting their conclusions. We hope Hawaii's citizens find that as inspiring as we do."

The virus has become an even greater public health threat since the infection was linked with severe birth defects—microcephaly—in the babies of some pregnant women.

University of Hawaii investigators believe their vaccine candidate may be safer than others currently in clinical trials because when the “recombinant subunit immunogens [included in the vaccine]… are properly folded and adjuvanted [they] can be used to prime and boost the immune response against a specific pathogen when introduced into the recipient, and [they] have one of the highest safety profiles.”

"We believe our vaccine candidate shows much promise particularly as it showed to require only 2 immunizations given 3 weeks apart and is a potentially safer alternative to other candidates already in clinical trials," Dr. Lehrer continued.