Vaccinations have begun in a first-in-human trial of an experimental live, attenuated Zika virus vaccine developed by scientists at the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health (USA).
National Institutes of Health (NIH), the U.S. national medical research agency, a component of the U.S. Department of Health and Human Services, is the primary federal agency conducting and supporting basic, clinical, and translational medical research, and is investigating the causes, treatments, and cures for both common and rare diseases.
The trial will enroll a total of 28 healthy, non-pregnant adults ages 18 to 50 at the Johns Hopkins Bloomberg School of Public Health Center for Immunization Research (Baltimore, Maryland, USA) and at the Vaccine Testing Center at the Larner College of Medicine at the University of Vermont (Burlington, USA). NIAID is sponsoring the trial.
Although most people experience a mild illness or no symptoms when infected with Zika virus, babies born to women infected with Zika virus during pregnancy may have birth defects and/or develop health problems in their early years.
Stephen Whitehead, Ph.D., of NIAID’s Laboratory of Viral Diseases, led the efforts to develop the experimental vaccine. The laboratory used genetic engineering techniques to create a chimeric virus, made by combining genes from multiple viruses. The chimeric virus consists of a dengue virus type 4 backbone (dengue is caused by any of four related viruses, termed serotypes) that expresses Zika virus surface proteins. The chimeric virus is live but attenuated, or weakened, so it cannot cause disease in recipients. When injected into the body, the weakened virus should prompt an immune response. The Phase 1 clinical trial will analyze this response in participants and assess the safety of the experimental vaccine, which showed promise in earlier tests in rhesus macaques (monkeys).
Dr. Whitehead also has developed a live, attenuated dengue vaccine candidate called TV003 designed to elicit antibodies against all four dengue virus serotypes. The experimental vaccine is currently under evaluation in a Phase 3 clinical trial conducted in Brazil by the Butantan Institute. Dr. Whitehead plans to develop a single vaccine that would protect against both Zika and dengue viruses. According to the CDC, dengue is endemic in at least 100 countries in Asia, the Pacific, the Americas, Africa and the Caribbean. Zika virus has been found to circulate in many of these same areas. Once the Zika vaccine candidate proves safe in Phase 1 clinical testing, Dr. Whitehead plans to add the Zika component to the tetravalent dengue vaccine candidate and evaluate the new pentavalent candidate in a Phase 1 clinical trial.
Anna Durbin, M.D., Professor of International Health at the Johns Hopkins Bloomberg School of Public Health and part of the university’s Center for Immunization Research, is leading the Phase 1 clinical trial of the monovalent Zika vaccine candidate. Dr. Durbin expects that the trial will take up to one year to complete.