Baby girls more susceptible to HIV than boys during pregnancy – Study

Baby girls are more likely to acquire HIV from their mothers during pregnancy or childbirth than infant boys, a new study published by Nature Medicine has revealed.

The baby boys, the research noted, are more likely to achieve cure or remission.

SciDev, a news platform that focuses on science and technology, in an analysis of the study published on its website, noted that it spotlights gender differences in immune systems.

Citing data from the World Health Organisation (WHO), SciDev noted that it is estimated that 1.3 million women and girls living with HIV become pregnant each year and the rate of mother-to-child transmission during pregnancy, labour, delivery or breastfeeding ranges from 15 to 45 per cent.

The researchers in the study evaluated 284 infants in KwaZulu-Natal, South Africa, one of the world’s highest HIV-prevalent areas, who received combination anti-retroviral therapy (cART) from birth, following exposure to HIV during pregnancy.

“We found that HIV transmission to male foetuses was 50 per cent less common than to females,” the Lead researcher, Philip Goulder, a professor of immunology at the University of Oxford told SciDev.

“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 – ie maintained undetectable levels of HIV in the blood even without therapy,”

Reduced infection in males

The researchers distinguish between two types of HIV cure: a “true cure,” where the virus is eliminated from the body, and a “functional cure” or “cure/remission,” where the virus becomes undetectable in the blood even after treatment is stopped.

According to Mr Goulder, the difference in HIV transmission rates between male and female infants is likely attributed to the lower levels of activated CD4 T cells in male foetuses, which creates a barrier against infection and makes it more difficult for the virus to establish a reservoir, thereby reducing the likelihood of the infection in males.

He said HIV struggles to survive in males due to a lack of CD4 cells.

“If by chance a virus gets transmitted to a male, it struggles to persist because there are not enough activated CD4 T cells to sustain the infection. That is why we are here,” he said.

CD4 T cells are vital components of the immune system that play a crucial role in fighting off infections like HIV.

Effective cure

The researchers also stated that the insights into HIV cure/remission gained from this study have far-reaching implications, offering hope for the development of effective cure strategies that could benefit not only children but also the estimated 39 million people worldwide living with HIV.

According to the co-author of the study at Queen Nandi Regional Hospital in KwaZulu-Natal, Nomonde Bengu, the ongoing study started in 2015 and takes in 30 infants per year with 315 enrolled to date.

“This is by some way the largest cohort of its type worldwide. We study and follow up not only the children living with HIV but also their mothers,” Ms Bengu said.

Ms Bengu said the unique opportunity to study mother-child pairs at the time of birth, when HIV is often diagnosed, has enabled researchers to identify and analyse the specific “founder virus” that was transmitted from mother to child.

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She explained that this has provided valuable insights into the early stages of HIV infection adding that “this is an extremely valuable resource in understanding the mechanism of cure/remission in children who later achieve it.”

Mr Goulder also admitted that remission in children may remain virus-free for life but long-term effects are unknown.

“The African child who is similar to those in our study has remained off therapy without detectable virus in the blood for 15 years, so far, and it is possible that some children may remain ART-free for life,” he said.

A Professor at the Department of Paediatrics and Child Health at Stellenbosch University, South Africa, Mark Cotton, noted that: “This paper adds impetus and knowledge to efforts to control HIV using immune system interventions.

“The study did unfold one of the complexities – female babies are more prone to acquire HIV. It also shows how children are worth studying in HIV clearance/control studies.”