London | A little-known virus infects the lining of the uterus in 43 per cent of women with unexplained infertility, a new study has found.
The study from University of Ferrara in Italy also found that the response of the immune system to HHV-6A virus – a member of the human herpesvirus family – infects may contribute to making the uterus less hospitable to a fertilised egg.
The virus seems to activate immune cells called natural killer cells in the uterus, and lead those cells to produce chemicals called cytokines. Cytokines are tools the immune system uses to orchestrate an attack on a foreign invader, like a virus.
However, the activated immune system cells and abnormal levels of certain cytokines may make it harder for a fertilised egg to lodge in the uterus, and grow into a baby. Infertility affects approximately six per cent of 15-44 year old women or 1.5 million women in the US, researchers said. About 25 per cent of female infertility cases are unexplained, leaving women with few options other than expensive fertility treatments.
If confirmed, the finding may lead to treatments that improve the outcome for a large subset of infertile women, said Anthony Komaroff, a professor at Harvard Medical School. Little is known about HHV-6A, which was discovered in 1986 and is one of nine human herpesviruses. Since HHV-6A is typically not detectable in the blood or saliva, its true prevalence is unknown.
A closely related virus, HHV6-B, is acquired by nearly 100 per cent of the population in early childhood and is spread through exposure to saliva. Currently, there are no approved drugs for HHV-6A or HHV-6B, but infectious disease specialists commonly use valganciclovir, foscarnet and cidofovir to treat HHV-6B reactivation in transplant patients.
These drugs were developed to treat human herpesvirus-5 (HHV-5), known as cytomegalovirus. More research is needed to confirm these findings and to determine whether antiviral treatment would help women with this uterine infection.
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