Chitra Pathak and Julie Clayton
A new approach to protecting newborn babies against HIV infection in KwaZulu-Natal is causing widespread excitement abroad, and could soon enter clinical trials.
It involves injecting babies with laboratory-made antibodies against the virus. Compared with the current practice of giving protective drugs to both a woman and her child, the new technique might enable women with the incurable Human Immunodeficiency Virus (HIV) to continue breastfeeding without transmitting the virus to their babies.
The trial involves injecting babies with antibodies that are designed to stick to the virus and thus stop it from entering a person's white blood cells. The idea is that antibodies would work like a vaccine and protect the baby against the virus — even if it was later exposed to HIV through its mother's breast milk.
In the absence of any treatment, more than a third of babies born to HIV-positive mothers develop the disease. Giving both mother and baby a single dose of the drug nevirapine can reduce transmission to around two per cent — but this only works if the mother avoids breastfeeding and instead uses commercial powdered milk.
Despite international guidelines advocating the use of powdered milk as 'best-practice' for HIV-positive mothers, many such women in Africa and Asia breastfeed because of social stigma attached to stopping breastfeeding, the high cost of powdered milk or a lack of clean water for making up milk formula.
"In developing countries such as India and South Africa it is not advisable or prudent to stop breastfeeding," says Hoosen Coovadia, lead investigator for the new clinical trial, from Durban. Coovadia, at the University of KwaZulu-Natal's Nelson Rolihlahla Mandela Medical School, is awaiting final authorisation from the trial sponsor, the United States' National Institutes of Health. "So we've been doing these studies to try to minimise the danger of breastfeeding transmission of HIV."
Coovadia's collaborator in the United States, Ruth Ruprecht of Harvard Medical School in Cambridge, Massachusetts, has already shown that, in laboratory tests, the same antibodies can prevent infection of cells in the laboratory by a wide range of different HIV strains. Moreover, the antibodies protect newborn monkeys whose mothers are infected with simian-human immunodeficiency virus, a laboratory model version of HIV. N. M. Samuel, a clinician and researcher at the Tamil Nadu Dr MGR Medical University in Chennai, India, and a leading authority on mother-to-child transmission of HIV, welcomes the antibody-based strategy.
"Mother-to-child transmission is very bad, particularly in sub-Saharan Africa," he says. "In Asia, it is getting worse, and that is also the case in countries such as Russia and its former allies…We would like to use the immune intervention to boost immunity, if we can."
The trial will take place at the Prince Mshiyeni Hospital in Umlazi in Durban, where about one in three pregnant mothers is infected with HIV. The first part of the trial will determine the safety of the antibody treatment and best dose to use in babies, and will take more than a year. If the results are promising, the researchers will conduct larger trials to see if the treatment protects the babies against infection.
At the same time, Coovadia and other teams in Africa and Asia are also investigating whether drugs such as nevirapine could be used to protect babies against HIV infection during breastfeeding. If so, it could be a race to see which approach works best — antibodies or drugs.
The potential advantage of the antibody approach is that it may avoid harmful side effects that can occur with drugs against HIV, including the appearance of drug-resistant HIV. But if the results of the drug trials appear first, and look promising, it may become difficult on ethical grounds to carry out tests using the antibodies alone.
"If using nevirapine in the baby works beautifully then we must give that, because it would be unethical not to," Coovadia concedes. He adds, however, that the antibody approach could instead be combined with drugs to delay disease progression, or with a future vaccine.- Source: Scidev.net