Just a quick post to let the community know about an experimental mRNA vaccine that may alleviate a lot of human misery due to HIV:
An experimental HIV vaccine based on mRNA—the same platform technology used in two highly effective COVID-19 vaccines—shows promise in mice and non-human primates, according to scientists at the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health. Their results, published in Nature Medicine, show that the novel vaccine was safe and prompted desired antibody and cellular immune responses against an HIV-like virus. Rhesus macaques receiving a priming vaccine followed by multiple booster inoculations had a 79% lower per-exposure risk of infection by simian-human immunodeficiency virus (SHIV) compared to unvaccinated animals. The research was led by Paolo Lusso, M.D., Ph.D., of NIAID’s Laboratory of Immunoregulation, in collaboration with other NIAID scientists, investigators from Moderna, Inc. and colleagues at other institutions.
[…] The experimental vaccine works like mRNA COVID-19 vaccines. However, instead of carrying mRNA instructions for the coronavirus spike protein, the vaccine delivers coded instructions for making two key HIV proteins, Env and Gag. Muscle cells in an inoculated animal assemble these two proteins to produce virus-like particles (VLPs) studded with numerous copies of Env on their surface. Although they cannot cause infection or disease because they lack the complete genetic code of HIV, these VLPs match whole, infectious HIV in terms of stimulating suitable immune responses.
[…] The team then tested the Env-Gag VLP mRNA vaccine in macaques. The details of the vaccine regimen differed among subgroups of vaccinated animals but involved priming the immune system with a vaccine modified to optimize antibody creation. The prime was followed by multiple booster inoculations delivered over the course of a year. The boost vaccines contained Gag mRNA and Env mRNA from two HIV clades other than the one used in the prime vaccine. The investigators used multiple virus variants to preferentially activate antibodies against the more conserved “shared” regions of the Env—the target of broadly neutralizing antibodies—rather than the more variable regions that differ in each virus strain.
Although the doses of mRNA delivered were high, the vaccine was well tolerated and produced only mild, temporary adverse effects in the macaques, such as loss of appetite. By week 58, all vaccinated macaques had developed measurable levels of neutralizing antibodies directed against most strains in a test panel of 12 diverse HIV strains. In addition to neutralizing antibodies, the VLP mRNA vaccine also induced a robust helper T-cell response.
It’s not clear to me from reading this whether this will help those already living with HIV, but it’s encouraging news to those who are at risk of becoming infected.