Early Administration of Antibodies Clears HIV in Animal Models

A recent development in HIV treatment showed that infant macaques with SHIV administered antibodies within 24 hours of exposure are able to completely clear the virus.

SHIV is a chimeric simian virus with the HIV envelope protein. SHIV infected nonhuman primates are able to transmit the virus to their babies through breastfeeding.

“We knew going into this study that HIV infection spreads very quickly in human infants during mother-to-child transmission," said senior author Nancy L. Haigwood, PhD. “So we knew that we had to treat the infant rhesus macaques quickly but we were not convinced an antibody treatment could completely clear the virus after exposure. We were delighted to see this result.”

The study administered anti-HIV-1 human neutralizing monoclonal antibodies (NmAb) subcutaneously on the first, fourth, seventh, and tenth day after the macaques were exposed orally to SHIV.

The results of the study published in Nature Medicine found a significant difference in treated versus non-treated macaques and the immediate impact of a single dose of antibodies at the beginning of the virus.

On day 1, the macaques that didn’t receive an antibody treatment had the SHIV virus in multiple body tissues. When early short-term antibodies were administered, by day 14 the virus was no longer detected.

By using highly sensitive methods, researchers were unable to detect SHIV in any part of the body in 100% of the infant macaques treated with antibodies for at least 6 months.

Although HIV will expand and spread to local draining lymph nodes in humans before disseminating throughout the body a week after exposure, the current study found that viral replication was detected in lymphatic tissues only 24 hours after exposure and was not locally restricted, like human HIV, which takes 5 to 7 days before detection in the blood.

“Other nonhuman primate studies with antiretroviral therapy suggest that treatment as early as 3 days after infection is too late to prevent establishment of the HIV reservoir,” said study co-author Jonah B. Sacha, PhD. “So using antibodies to clear the virus after infants have already been exposed could save thousands of lives (if it works in human infants).”

Currently, clinical trials in the United States and South Africa have begun using HIV infants being treated with antibodies.