by Cassandra R. Elias
Even though breastfeeding is blamed for a significant number of HIV infections in infants, most babies breastfed by HIV-infected moms are not infected with the virus, despite prolonged and repeated exposure.
HIV researchers have been left with a conundrum: Does breast milk transmit the virus or protect against it?
New research from the University of North Carolina School of Medicine indicates that breast milk has a strong virus-killing effect. It appears to protect against the oral transmission of HIV.
The researchers created a genetically modified mouse by introducing human bone marrow, liver and thymus tissues into the animals. These "humanized" mice have a fully functioning human immune system and can be infected with HIV in the same manner as humans.
In the study, the researchers first successfully transmitted the virus to the mice orally.
Then other mice were given the virus in whole breast milk from HIV-negative women. When the virus was introduced in breast milk, it could not be transmitted.
"These results are highly significant because they show that breast milk can completely block oral transmission of both forms of HIV that are found in the breast milk of HIV-infected mothers: virus particles and virus-infected cells," Angela Wahl, PhD, a post-doctoral researcher in Garcia’s lab and lead author on the paper, said in a released statement.
She explains that this research "...refutes the 'Trojan horse' hypothesis which says that HIV in cells is more stubborn against the body's own innate defenses than HIV in virus particles."
The World Health Organization recommends that mothers breastfeed infants exclusively for the first six month, even mothers who are HIV-infected.
The CDC recommends that an HIV-positive woman feed her baby formula, if clean water and medical care is available. This study could change the recommendation.
"No child should ever be infected with HIV because it is breastfed. Breastfeeding provides critical nutrition and protection from other infections, especially where clean water for infant formula is scarce," said J. Victor Garcia, PhD, senior author on the study and professor of medicine in the UNC Center for Infectious Diseases and the UNC Center for AIDS Research. "It also provides new leads for the isolation of natural products that could be used to combat the virus."
A next step in the research would be to compare the breast milk of HIV-infected mothers who transmit the virus to their babies with the breast milk of those who did not. Wahl says that they would look for differences and for other method of transmission such as mastitis which can cause bleeding nipples.
Another future research goal is to pinpoint the specific compounds in breast milk that potentially have HIV-killing abilities. Once identified, researchers could use the humanized mouse model to test and see if these factors could inhibit against all types of HIV transmission -- oral, rectal and vaginal.
What do you think of these new findings?