NIH Launches Clinical Trial for Zika Virus Vaccine Candidate

Today, August 20, 2018, is World Mosquito Day, an observance that has been established in honor of when Sir Ronald Ross discovered that mosquitoes transmit the malaria parasite to humans in 1897.

According to the World Health Organization (WHO), mosquitoes are 1 of the world’s most deadly animals as they are known to carry diseases such as malaria, dengue, chikungunya, yellow fever, and Zika virus.

Zika transmission has proven to be serious, specifically when the virus is transmitted from mother to unborn child. Birth defects and developmental delays have been reported in 1 in 7 children >1 year who were born from women with potential or confirmed Zika infection during pregnancy, stressing a need for stronger preventive measures to protect against the virus.

In an effort to fulfill that need, investigators have announced the first in-human trial for an experimental Zika virus vaccine candidate referred to as rZIKV/D4Δ30-713, developed by scientists at the National Institute of Allergy and Infectious Diseases (NIAID) part of the National Institutes of Health (NIH). For the phase 1 trial, investigators will assess the safety of the vaccine as well as immune response in participants.

To develop the vaccine, investigators used genetic engineering to combine genes from multiple viruses to create a chimeric virus. The virus featured a dengue virus type 4 “backbone” with Zika virus surface proteins. When administered via injection, the virus should initiate an immune response.

Steven Whitehead, PhD, of NIAID’s Laboratory of Viral Diseases who has led the efforts to develop the vaccine, explained the make-up of the vaccine candidate to Contagion®. “rZIKV/D4Δ30-713 is an experimental live, attenuated Zika vaccine expected to be highly immunogenic and induce lifelong immunity after one dose,” he explained. “The platform used has been successful for other flaviviruses, including yellow fever, Japanese encephalitis, and dengue.”

The vaccine showed promising results when tested in rhesus macaques. However, according to Dr. Whitehead, the data pertaining to this trial is still pending publication and cannot be discussed in detail yet.

The phase 1 in-human clinical trial will enroll at total of 29 healthy adults between the ages of 18 to 50 years. Volunteers must not have a history of any flavivirus infection in order to measure the vaccine’s ability to create antibodies.

Twenty participants will be randomly assigned to receive a single subcutaneous dose of the vaccine candidate. The remaining 8 volunteers will receive a placebo.

All participants will be asked to track their temperature in a diary at particular timepoints. Participants will also return to the clinic for examinations and to submit blood samples in the 6 months following the vaccination. Investigators will analyze the blood samples to determine whether or not participants are developing antibodies in response to the vaccine.

The trial is expected to take up to 1 year.

According to the statement, Dr. Whitehead has also developed TV003, a dengue vaccine candidate. The candidate is a live, attenuated vaccine designed to create antibody response to all 4 serotypes of dengue. If the phase 1 trial of rZIKV/D4Δ30-713 proves that the vaccine is safe, Dr. Whitehead plans to combine the components of both vaccines to create a “pentavalent candidate.”

“The vaccine is economical to produce and is compatible for combination with our existing live, attenuated DENV vaccine,” Dr. Whitehead told Contagion®, “Additionally, the vaccine induces both humoral and cellular immune responses, and the antigens and epitopes are in their native conformation.”