Women having unsafe sex may be at more risk of HIV than thought after tests revealed the HPV virus could breach even healthy vaginal tissue.
It had been believed that only damaged skin inside the vagina could provide a route to infection.
However, US-based researchers say HIV infection can get past this intact barrier within hours.
UK HIV charities said it reinforced the need for women to avoid unprotected sex unless their partner’s health is known.
The lining of the vagina – the squamous epithelium – had been believed by many to be capable of keeping HIV at bay.
While transmission of the virus from men to women through unprotected sex is commonplace in many parts of the world, it was thought that HIV was most likely traveling through cuts or sores in the vaginal tract (vaginal problems), or penetrating a much thinner layer of skin further up the reproductive tract.
The scientists from Northwestern University in Chicago found that, far from this being the truth, HIV could move quickly between the skin cells themselves.
Read more at BBC News