New trial of a preventive HIV vaccine candidate begins in the United States and South Africa

Reviewed by Megan Craig, M.Sc.Sep 20 2023

A trial of a preventive HIV vaccine candidate has begun enrollment in the United States and South Africa. The Phase 1 trial will evaluate a novel vaccine known as VIR-1388 for its safety and ability to induce an HIV-specific immune response in people. The National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health, has provided scientific and financial support throughout the lifecycle of this HIV vaccine concept and is contributing funding for this study.

VIR-1388 is designed to instruct the immune system to produce T cells that can recognize HIV and signal an immune response to prevent the virus from establishing chronic infection. VIR-1388 uses a cytomegalovirus (CMV) vector, meaning a weakened version of CMV delivers the HIV vaccine material to the immune system without causing disease in the study participants. CMV has been present in much of the global population for centuries. Most people living with CMV experience no symptoms and are unaware that they are living with the virus. CMV remains detectable in the body for life, which suggests it has the potential to deliver and then safely help the body retain HIV vaccine material for a long period, potentially overcoming the waning immunity observed with more short-lived vaccine vectors.

NIAID has funded the discovery and development of the CMV vaccine vector since 2004 and is funding this trial with the Bill & Melinda Gates Foundation and Vir Biotechnology, based in San Francisco. The trial is sponsored by Vir and conducted through the NIAID-funded HIV Vaccine Trials Network (HVTN) as study HVTN 142.

HVTN 142 is taking place at six sites in the United States and four in South Africa and will enroll 95 HIV-negative participants. Participants will be randomly assigned to one of four study arms: three arms will each receive a different dose of the vaccine, and one will receive a placebo. To optimize participant safety, this study will only enroll people already living with asymptomatic CMV. Initial results are expected in late 2024, and an optional long-term sub-study will continue to follow volunteers for up to three years after their first vaccine dose.