New research on nonhuman primates has found that a single dose of antibody-based treatment can prevent HIV transmission from mother to baby. Published in Nature Communications, this research is the first to find that a single dose of broadly neutralising antibodies given after viral exposure can prevent SHIV infection in nonhuman primate newborns.

The human immunodeficiency virus (HIV) causes HIV infection and over time acquired immunodeficiency syndrome (AIDS), where it causes progressive failure of the immune system and allows life-threatening opportunistic infections and cancers to thrive. The average survival time after HIV infection is around 9-11 years without treatment, and current treatments work to slow the progression of the virus in the body.

This new study used rhesus macaque new-borns to investigate the transmission of the monkey form of HIV, called SHIV, from mother to baby. They used a combination of two antibodies called PGT121 and VRC07-523.

When the rhesus macaques received a single-dose combination of two antibodies 30 hours after being exposed to the virus, they did not develop SHIV.  When the treatment was delayed for 48 hours, half of the baby macaques developed SHIV when they were given four smaller doses of the same antibody combination. In contrast, when using current standard HIV treatment – antiretroviral drugs – after 48 hours, the baby macaques remained SHIV-free with a three-week regimen of therapy.

The researchers found that when using antibodies, when the single dose is given is key. Their findings could mean less treatment can be used and still beat HIV in babies born to HIV-positive mothers.

When babies are born from HIV-positive mothers, they are all typically given antiretroviral therapy daily for about six weeks before being re-tested to further prevent infection. It’s not certain that they will be HIV free, so if the test comes back positive, they will most likely need to take HIV drugs for the rest of their lives. Many negative side effects come with using antiretroviral therapy, and researchers also worry about its long term effect on development.

In contrast, antibodies aren’t toxic and can be modified to last a long time in the body, reducing treatment frequency. The researchers are now looking at the potential to increase the effectiveness of the antibodies and whether it can replace or supplement antiretroviral therapy for new-borns with HIV-positive mothers, as well as for HIV-positive adults.

The teams next steps include identifying the most effective combination of treatment and determine how the antibodies work – if they eliminate HIV or only prevent it from replicating.

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