Some Cases of Primary Unexplained Infertility Might Have a Viral Cause

Viral infections have long been suspected to be a cause of primary unexplained infertility, but no viruses have been implicated. Italian investigators studied 30 women with unexplained primary infertility and a control group of 36 age-matched women with at least one successful pregnancy.

Half of women with primary infertility — but no controls — harbored human herpesvirus (HHV)-6A in endometrial cells. In contrast, no HHV-6B (a different herpesvirus) was found in any endometrial samples. Moreover, the concentration of HHV-6A was substantial, and HHV-6A proteins also were detected by immunohistochemistry. Striking differences between groups were seen in the endometrial “immune milieu”: Different types of natural killer lymphocytes were found,…