A single dose of antibody treatment was effective in preventing the transmission of HIV between mother monkeys and their newborns, paving the way for future research exploring how similar treatments may benefit humans.
When given to a newborn within 30 hours after exposure to the simian-human immunodeficiency virus (SHIV) – the monkey version of HIV – a combined dose of two antibodies called PGT121 and VRC07-53 was proven effective in preventing virus expression in the monkey. However, the researchers are not clear whether the treatment eliminates HIV or simply prevents it from replicating.
"These promising findings could mean babies born to HIV-positive mothers can still beat HIV with less treatment," said the study's corresponding author Nancy Haigwood, professor of pathobiology and immunology in the Oregon Health and Science University (OHSU) School of Medicine, as well as the director at the Oregon National Primate Research Center at OHSU, in a statement.
The use of antiretroviral therapy (ART) in recent years has made HIV-1 a “manageable chronic infection for patients with access to treatment.” HIV is a challenging disease to treat as the virus rapidly mutates when it copies itself. ART treatments work by preventing HIV from multiplying. In people living with HIV, the immune system does not properly respond to the virus for many reasons. To combat this, researchers have developed a treatment known as broadly-neutralizing antibodies (bNabs), which “neutralizes” genetic variants of HIV and has implications for prevention intervention and vaccine development. (The concept is currently in clinical trials in humans in several countries around the world.)
HIV-positive women typically take antiretroviral drugs during therapy to prevent passing on the virus in utero. Even so, mother-to-baby transmission still occurs when an infant is exposed to its mother's blood or other fluids, either through pregnancy, childbirth, or breastfeeding. Human babies born from HIV-positive mothers take a drug cocktail for up to six weeks after birth in case they were exposed to the virus, at which point they are then tested for HIV. If positive, it is likely the infant will need to take HIV drugs for the rest of their lives.
Publishing their work in Nature Communications, the researchers found that all rhesus macaque infants given a single dose of the antibodies within 30 hours of birth had virtually no virus present in their tissues. But timing is key – delaying treatment until 48 hours after exposure resulted in half of the macaques developing SHIV. Here’s where a secondary treatment comes in. After the 48-hour window, macaque babies who were treated with a three-week regime of ART drugs also remained SHIV-free. By comparison, monkeys that weren’t treated showed signs of rapid disease progression.
ART drugs in newborn children may have negative side effects and the long-term consequences for development are not immediately known. Because antibodies are non-toxic and can be modified to last for a longer duration in the body, the researchers suggest the treatment could someday supplement or replace ART drugs.