Baby girls are more likely to acquire HIV from their mothers during pregnancy or childbirth than infants, who in turn are more likely to achieve treatment or remission, researchers say in a new study that sheds light on gender differences in the immune system.
An estimated 1.3 million women and girls living with HIV become pregnant each year, and the rate of transmission to the child during pregnancy, labor, delivery or breastfeeding – in the absence of any intervention – ranges from 15 to 45 percent, according to the World Health Organization.
Lead researcher Philip Goulder says the study has identified some of the key mechanisms by which sustained HIV remission can be achieved – mechanisms that are relevant in children and adults.
Goulder and colleagues evaluated 284 infants in KwaZulu-Natal, South Africa, one of the highest HIV prevalence regions in the world, who were started from birth on a mix of HIV drugs known as combination antiretroviral therapy (cART). , after being exposed to HIV during pregnancy.
“We found that transmission of HIV in male fetuses was 50 percent less frequent than in female fetuses,” says Goulder, a professor of immunology in the Department of Pediatrics at the University of Oxford in the United Kingdom.
“The affected males had lower levels of the virus in the blood, and to date, in this study, four male infants have been identified who have achieved HIV cure/remission – that is, maintained undetectable levels of HIV in the blood even without treatment,” he said. SciDev.Net.
HIV treatment is categorized as ‘true cure’ in which the virus has been completely eliminated from the body and ‘functional cure’ or ‘cure/remission’ in which the virus is no longer detectable in the blood even after treatment is stopped .
Goulder said the difference found between male and female infants is likely due to lower levels of activated CD4 T cells in male fetuses than in females, making it harder for the virus to create a reservoir and providing a barrier against infection.
If by chance a virus is transmitted to a man, it has a hard time persisting because there aren’t enough activated CD4 T cells available to sustain the infection.”
Philip Goulder, Philip Goulder, Professor of Immunology, University of Oxford, Department of Paediatrics
“That’s what we think is happening here.”
CD4 T cells are a type of white blood cell that help the body fight infections such as HIV. They are an important part of the immune system and are targeted by HIV during infection. HIV spreads more slowly with lower CD4 T cell counts.
The study, published last month in the open-access journal Nature Medicine, adds to existing knowledge about HIV treatment/remission and could be relevant to treatment strategies not only aimed at children but also those targeting all 39 million people living with HIV worldwide, according to the researchers.
“This is a revolutionary result in South Africa, where almost eight million people are living with HIV,” said study co-author Nomonde Bengu at the Queen Nandi District Hospital in KwaZulu-Natal.
The ongoing study began in 2015 and accepts 30 infants annually with 315 enrolled to date.
“This is by some means the largest group of its type worldwide,” Bengu told SciDev.Net.
“We study and monitor not only children living with HIV but also their mothers.”
Access to the mother and child at the time of birth, when HIV can be diagnosed, allowed researchers to study the specific virus that was transmitted – the so-called “founder virus,” says Bengu.
“This is an extremely valuable resource for understanding the mechanisms of recovery/remission in children who later achieve it,” he adds.
The researchers, however, say that some of the male infants still have some very low levels of HIV antibodies in their blood.
“The long-term effects on children are unknown,” Goulder admits.
“The African child similar to those in our study has remained off treatment without detectable virus in the blood for 15 years, so far, and it is possible that some children remain ART-free for life.”
The findings match exactly what is known about HIV infection in adults, according to the researchers.
They add that the mechanisms by which HIV cure/remission can be achieved are potentially applicable across the board and to the 39 million people living with HIV.
The number of children we identified who achieved treatment/remission is small, and further studies would be important, the researchers acknowledge.
But they say it’s a step up from previous studies that only identified individual children who achieved cure/remission.
“This work adds momentum and insight to efforts to control HIV using immune system interventions,” says Mark Cotton, associate professor in the Department of Paediatrics and Child Health at Stellenbosch University in South Africa, who was not involved in the research.
“The study unraveled one of the complexities – female babies are more prone to get HIV. It also shows how children are worth studying in HIV clearance/control studies.”
