New South African approach to
protecting babies from AIDS
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
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