Wednesday, 23 May 2012
Breast milk antibodies help neutralize HIV
Breast milk may hold key to developing vaccine for HIV.
Antibodies that help to stop the HIV virus have been found in breast milk
Researchers at Duke University Medical Center isolated the antibodies from immune cells called B cells in the breast milk of infected mothers in Malawi, and showed that the B cells in breast milk can generate neutralizing antibodies that may inhibit the virus that causes AIDS.
HIV-1 can be transmitted from mother to child via breastfeeding, posing a challenge for safe infant feeding practices in areas of high HIV-1 prevalence. But only one in 10 HIV-infected nursing mothers is known to pass the virus to their infants.
“That is remarkable, because nursing children are exposed multiple times each day during their first year of life,” said senior author Sallie Permar, M.D., Ph.D., an assistant professor of pediatrics and infectious diseases at Duke.
“We are asking if there is an immune response that protects 90 percent of infants, and could we harness that response to develop immune system prophylaxis (protection) during breastfeeding for mothers infected with HIV-1.
“Our work helped establish that these B cells in breast milk can produce HIV-neutralizing antibodies, so enhancing the response or getting more mucosal B-cells to produce those helpful antibodies would be useful, and this is a possible route to explore for HIV-1 vaccine development,” Permar said.
The study was co-authored by Barton Haynes, M.D., a national leader in AIDS/HIV research, director of the Center for HIV/AIDS Vaccine Immunology (CHAVI), as well as director of the Duke Human Vaccine Institute (DHVI).
“This is important work that seeks to understand what a vaccine must do to protect babies from mucosal transmission during breastfeeding,” said Haynes.
“The antibodies isolated are the first HIV antibodies isolated from breast milk that react with the HIV-1 envelope, and it important to understand how they work to attack HIV-1,” he stated.
The findings of two different antibodies with HIV-neutralizing properties isolated from breast milk also may help researchers with new investigations into adult-to-adult transmission, in addition to mother-to-child transmission.
Permar said that most HIV-1 transmission occurs at a mucosal site in the body – surfaces lined with epithelial cells, such as the gastrointestinal tract or vaginal tissue. The mucosal compartments all have their own immune system cells.
“We’re excited about this finding because the immune cells in mucosal compartments can cross-talk and traffic between compartments. So the antibodies we found in breast milk indicate that these same antibodies are able to be elicited in other tissues,” Permar said.
The study was published on May 18 in PLoS One, an open-access journal published by the Public Library of Science.