New way men can transmit HIV to women

CHICAGO, Dec. 25 (UPI) -- Researchers at Northwestern University in Chicago say they have found a critical way a man can transmit the HIV virus to a woman.

The researchers showed that the HIV virus can penetrate a woman's normal, healthy genital tissue to a depth where it can gain access to immune cell targets.

"This is an unexpected and important result," principle investigator Thomas Hope said in a statement. "We have a new understanding of how HIV can invade the female vaginal tract."

Scientists had long believed that the normal lining of the female vaginal tract was an effective barrier to invasion of the HIV virus during sexual intercourse and that the large HIV virus couldn't penetrate the tissue, Hope said.

Hope, his Northwestern colleagues and collaborators at Tulane University in New Orleans, discovered that interior vaginal skin is vulnerable to HIV invasion at the level where it naturally sheds and replaces skin cells -- a point at which the cells are not as tightly bound together.

The Centers for Disease Control and Prevention in Atlanta estimated there were 56,300 new HIV infections in 2005 and traced 31 percent of the total to high-risk heterosexual contact.

Hope presented his findings at the American Society for Cell Biology 48th annual meeting in San Francisco.