Antibody cocktail better in preventing HIV infection: studies

Scanning electron micrograph of HIV-1 budding (in green) from cultured lymphocyte. This image has been colored to highlight important features; see PHIL 1197 for original black and white view of this image. Multiple round bumps on cell surface represent sites of assembly and budding of virions. (Photo by C. GoldsmithContent Providers: CDC/ C. Goldsmith, P. Feorino, E. L. Palmer, W. R. McManus -, Public Domain)

WASHINGTON — A cocktail of two or three antibodies could be more effective than a single one in preventing Human Immunodeficiency Virus (HIV) transmission, according to results released Wednesday from two separate monkey studies.

In a study published in the US journal Science, researchers combined three broadly neutralizing antibodies (bNAbs) — VRC01, PGDM1400, and 10E8v4 — into a three-pronged antibody to mount a stronger immune response.

The so-called “trispecific” antibody, made by researchers from the US National Institutes of Health (NIH) and the Paris-based pharmaceutical company Sanofi, works by binding to three different critical sites on HIV.

After exposing 24 monkeys to two strains of a monkey form of HIV, researchers found the majority of those receiving either PGDM1400 or VRC01 developed infection but all those receiving the triple combination were fully protected from the virus.

The three-pronged antibody was also found able to stop a greater number of HIV strains from infecting cells in the laboratory more potently than natural, single antibodies.

“Plans are underway to conduct early-phase clinical trials of the ‘trispecific’ antibody in healthy people and in people living with HIV in the hope that it could eventually be used for long-acting HIV prevention and treatment,” the NIH said in a statement.

“By binding to three different sites on the virus, the new antibody should be harder for HIV to dodge than natural, single antibodies.”

In another study published in the journal Science Translational Medicine, researchers administered two different bNAbs to monkeys before infecting them with two strains of a monkey form of HIV.

Monkeys receiving either of the two antibodies individually all became infected, yet those with both antibodies conferred 100 percent protection.

“These data reveal that single bNAbs efficiently select resistant viruses from a diverse challenge swarm to establish infection, demonstrating the importance of bNAb cocktails for (HIV) prevention,” said the study led by researchers from Harvard University.