A new study from the University of Ferrara in Italy reveals that a lesser-known virus, human herpesvirus 6A (HHV-6A), infects the uterine lining in 43% of women suffering from unexplained infertility. In contrast, this virus was not detected in the uterine lining of women who are fertile.
The research suggests that the immune response to HHV-6A may make the uterus less welcoming for a fertilized egg. The virus appears to trigger natural killer cells, a part of the immune system, causing them to release cytokines. These signaling molecules help the body fight infections. However, the overactive immune response and abnormal cytokine levels might interfere with the fertilized egg’s ability to implant and develop in the uterus.
Infertility affects about 6% of women aged 15 to 44 in the United States, totaling roughly 1.5 million women, according to the Centers for Disease Control and Prevention (CDC). Around 25% of these infertility cases have no clear cause, leaving many women with limited options beyond costly fertility treatments.
Anthony Komaroff, a professor at Harvard Medical School and expert on HHV-6, called the discovery “surprising and potentially important.” He noted that if confirmed, these findings could lead to new treatments to help a significant number of women struggling with infertility.
HHV-6A is one of nine human herpesviruses identified since 1986. It is different from the more common HHV-6B, which nearly everyone contracts during childhood through saliva. HHV-6B is known to cause roseola, a mild illness in infants, and can lead to serious complications in people with weakened immune systems.
Currently, no drugs have been approved specifically for HHV-6A or HHV-6B. However, doctors sometimes use antiviral medications like valganciclovir, foscarnet, and cidofovir to treat HHV-6B reactivation in patients who have undergone organ transplants. These drugs were originally developed to fight cytomegalovirus (HHV-5).
Further research is needed to verify these results and explore whether antiviral treatments could benefit women infected with HHV-6A in the uterus. Testing for this infection can be done through a simple biopsy of the uterine lining, a standard gynecological procedure performed without anesthesia using a small suction device.
This discovery opens a new path toward understanding and potentially treating a common yet mysterious cause of female infertility.
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