A little-known virus has been found in the uteruses of around half of women with unexplained infertility, a study has found.

The findings, if confirmed, could potentially lead to antiviral treatments for the approximately 25 percent of women whose infertility has no medical explanation.  

Researchers from the University of Ferrara, Italy, examined the uteruses of 30 women with unexplained primary infertility and compared them with 36 controls, each of whom had had at least one successful pregnancy.

They found DNA from human herpesvirus HHV-6A in 43 percent of those with unexplained infertility but in none of the fertile controls. The study was published in PLOS One.

Little is known about HHV-6A but it is closely related to HHV-6B, which almost everyone gets during childhood. It causes short-term fever, diarrhoea and rashes. Herpesviruses remain dormant and may become reactivated later in life.

The researchers also found infertile women with HHV6-A had higher levels of natural killer cells in their uterus compared with the fertile women. Natural killer cells are immune cells that form part of the first line of defence against viral infection, but they may make the environment of the uterus less hospitable to a fertilised egg, decreasing the chance of implantation in the womb lining.

Recent studies have implicated members of the herpesvirus family in male infertility but this is the first link with female infertility to have been identified.

'This is a surprising discovery,' said Professor Anthony Komaroff of Harvard Medical School, who was not involved in the study. 'If confirmed, the finding has the potential to improve the outcome for a large subset of infertile women.'

Currently, there are no drugs for the treatment of HHV-6, but treatments for the herpesvirus-5 (HHV-5) – also known as cytomegalovirus – are currently being used to treat HHV-6B reactivation in transplant patients.

Reproduced from BioNews with permission, a web- and email-based source of news, information and comment on assisted reproduction and human genetics, published by Progress Educational Trust.