A combination of broadly neutralizing antibodies protected monkeys from infection with an HIV-like virus better than single antibodies in two recent, separate studies.
The results offer further evidence that a combination strategy may be the key to preventing HIV infection. Previous studies have found that individual antibodies do not provide sufficient protection from the virus.
“The virus is just so good at mutating away from any single thing we throw at it,” said amfAR Vice President and Director of Research Dr. Rowena Johnston in an interview with HealthDay. “When we treat HIV, you can’t give a single antiretroviral drug. You have to give a combination of at least two and optimally three. They are now also looking at this idea for antibodies.”
In one study, an amfAR-funded research team injected monkeys with a cocktail of two HIV-blocking antibodies and then exposed them to two different strains of SHIV (a combination of HIV and SIV—the simian version of HIV). Each strain was vulnerable to one of the antibodies.
The monkeys that received one of the antibodies individually became infected with the strain that was not sensitive to the one antibody; however, when they received the two-antibody cocktail, they were protected against both.
In the other study, scientists from the National Institutes of Health (NIH) and the Paris-based pharmaceutical company Sanofi created a three-pronged antibody based on three individual antibodies, each of which neutralizes many strains of the virus. The “trispecific” antibody binds to three different vulnerable sites on the virus.
None of the monkeys given the three-pronged antibody became infected after being exposed to two strains of SHIV.
Plans are underway to begin clinical trials of both the trispecific antibody and the two-antibody cocktail in the hope of eventually using the strategies for both HIV prevention and treatment.
However, as Johnston noted to HealthDay, all antibodies die off quickly. That means, “if you were going to use these in clinical practice to prevent HIV infection, you would have to repeatedly administer them,” perhaps as often as every several weeks, she said.
Read a press release on the NIH study here.