Why some women get HIV but others don’t

Posted by Jambo 

The biological make-up of a woman’s vagina could protect her from HIV, experts have discovered. HIV particles are effectively trapped by the vaginal mucus in women who harbour a particular species of bacteria, they said.

Those found to have lactobacillus crispatus appear to have a greater ability to protect against the Aids-forming virus.

Scientists at the University of North Carolina hope their findings will pave the way for new treatments to block vaginal transmission of the disease, and other Sexually Transmitted Infections.

They collected fresh cervicovaginal mucus (CVM) samples from 31 women, of reproductive age. They measured various properties of the mucus, and used high-resolution, time-lapse microscopy to test whether fluorescent HIV pseudovirus particles became trapped in the mucus, or if they difused freely.

Their findings revealed two distinct populations of CVM samples one that was very good at trapping HIV, and one that was not.

The researchers noted that the ability of a woman’s CVM to trap the virus was not related to its pH, total lactic acid, or Nugent score a rough measure of vaginal health, which reflects how many lactobacillus bacteria are present compared to other microbes.

CVM can act as a barrier to prevent pathogens from reaching the underlying vaginal wall cells. But, the barrier properties vary greatly from woman to woman, and can even vary at different times in the same woman.

The finding was significant because humans cannot make D lactic acid. The team suspected that different bacteria living within the mucus layer were responsible for these differences in D lactic acid.

To test their theory, the scientists tested the samples to identify the individual strains of bacteria. Their findings revealed two distinct groups once more.

In those samples that trapped HIV, they found L crispatus bacteria dominated. In contrast, those CVM samples that failed to trap the virus, either possessed a different lactobacillus species, L iners, or had multiple bacterial species present, including gardnerella vaginalis both of which are associated with bacterial vaginosis.

Past studies have found clear links between bacterial vaginosis and having a higher risk of acquiring and transmitting STIs. The team found L. crispatus caused CVM to be more ‘sticky’ against HIV particles, rather than making a tighter mucus mesh.

-DAILY MAIL