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Antibodies in breast milk found to neutralize HIV

Duke researchers have isolated an antibody that could aid in the creation of an HIV vaccine.

A research team led by Dr. Sallie Permar, assistant professor of pediatrics and infectious diseases, isolated antibodies that can neutralize HIV in the breast milk of infected mothers in Malawi. The discovery, published in the journal PLoS One last month, could be used to make a vaccine that produces antibodies with extensive virus-resistant capabilities.

“The broadly neutralizing antibodies are those that are capable of blocking infection from a lot of different [HIV] strains,” said co-author Dr. M. Anthony Moody, assistant professor in the department of pediatrics in the division of infectious diseases. “Those antibodies are a lot rarer to find, but we are interested in producing a vaccine that will allow for these types of antibodies to enter the body.”

HIV is able to mutate very quickly, making it difficult for the body to naturally produce antibodies that can successfully fight every variant of the virus, Permar said.

Of the two types of antibodies found in the study, one has broad neutralizing capabilities, making it an ideal candidate for the vaccine, Moody noted.

“We have some hope that an antibody with this capability, made by immune cells in breast milk, has enough reach to be able to neutralize many different variants,” Permar said.

James Friedman, a third-year medical student and author on the study, noted that if the antibodies found are able to neutralize HIV before it is transmitted to an infant, they could be promising for creating a vaccine.

“Are antibodies able to inhibit HIV in the infant as well as the mother? That’s sort of the million dollar question,” he said. “That would mean a normal human body is able to produce protective antibodies, and the ultimate goal is to identify them so that they can be used in a vaccine.”

The researchers conducted the study through the Duke Human Vaccine Institute as part of its ongoing efforts to produce an HIV vaccine, Permar said.

Dr. Barton Haynes, director of DHVI, could not be reached for comment.

Friedman noted that the study was not easy to conduct because the breast milk had to be shipped overseas, endangering some of the B-cells, which produce antibodies.

“It’s not a perfect process—a lot of the B-cells didn’t survive the trip,” he said. “I’m sure with better technology and shipping we can identify more antibodies.”

Moody added that there would have been benefits to conducting the research on-site, but this was not possible because site in Malawi does not have sufficient infrastructure, such as reliable sources of power or water. The problems posed from the location would have prevented the technology used from working properly.

Although mother-child transmission of HIV is possible, only 10 percent of breast-feeding infants will become infected, Permar said. This is a “remarkable” fact considering infants are exposed to HIV through breast-feeding multiple times a day for up to two years.

“When you have an HIV-infected mother in a resource poor area, it’s not ethical to recommend that she not breast-feed her infant,” Permar said. “That’s why it’s important to try and determine a way that HIV-infected mothers can breast-feed their children and protect them from HIV as well.”

She noted that there are currently many ways to reduce the risk of mother-child transmission. It is possible to reduce the risk of mother-child transmission by giving mothers anti-retroviral drugs during breast-feeding, Permar said. This reduces the risk of transmission from 10 percent to between 1 and 2 percent.

“The challenge, then, is that if there is still that 1 to 2 percent then there are still a couple of infants infected,” she said. “Our goal is to make breast-feeding completely safe, and vaccines not only accomplish this, but are easier to implement.”

Although this discovery expands the arsenal available to HIV researchers, it forms just a small piece in the large puzzle that is the HIV vaccine, Friedman noted.

“Isolating these antibodies, along with all the others that have been isolated individually, isn’t very important—but the hope is that as we identify even more, we can put together a bigger picture and find the best ways to target HIV with a vaccine,” Friedman said.

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