Almost half of women with unexplained fertility problems are infected with a mysterious virus, a study suggests. The discovery has raised hopes that tens of thousands of women who struggle to conceive could be treated with an antiviral drug. In a quarter of all female infertility cases – accounting for about one in 70 women aged under 44 – doctors are unable to say why they cannot get pregnant.
The small study from Italy indicated that a virus from the herpes family may be to blame for a significant number of these problems. It seems to trigger a cascade of immune effects in the womb that could make it harder for embryos to flourish. The scientists said that if their findings were confirmed, the infections could be wiped out with customised drugs.
A team of researchers led by the University of Ferrara took tissue samples from the womb linings of 30 mothers and 30 women with unaccountable infertility. They found that DNA from the HHV-6A virus in 13 of the infertile women, but none of the fertile ones. The virus was discovered 30 years ago but is still poorly understood. Other viruses in the herpes group have been linked to male infertility.
Writing in the online journal Plos One, the scientists said that HHV-6A appeared to infect a wide variety of the womb’s immune cells and infections seemed to be exacerbated by high levels of the hormone estradiol, which triggers ovulation and helps to prepare the womb for the embryo.
Roberta Rizzo, who supervised the work, said that the virus could make underlying fertility problems worse. It may be sexually transmitted.
Although the numbers of women involved in the initial research were small, the results seemed to hold true in a wider sample, she added.
There are no drugs specifically designed to attack the HHV-6A virus but doctors use a range of broader-spectrum antiviral treatments such as valganciclovir, foscarnet and cidofovir.
Dr Rizzo said that a woman with fertility problems could take the drugs before trying to conceive naturally and they would clear from her system in time for the embryo to be implanted.
Ursula Gompels, reader in molecular virology at the London School of Hygiene and Tropical Medicine, who was not involved in the work, said it opened up a new frontier in the struggle against fertility problems.
“This is a potentially important result,” she said. “The next steps will be to determine further whether this is indeed due to the virus, or [to] changes in immunity in these women – possibly a combination.”
She added: “There are currently drugs which can treat related viruses and these show some efficacy [against HHV-6A] in the lab. However, this could be toxic to a developing foetus, and a better drug or vaccine would be required.”