A new study has found that the little-known member of the human herpesvirus family called HHV-6A infects the lining of the uterus in 43% of women with unexplained infertility but cannot be found in uterine lining of fertile women. The study was conducted by investigators at the University of Ferrara, Italy.
The study also found that the response of the immune system to the virus may contribute to making the uterus less hospitable to a fertilized 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 fertilized egg to lodge in the uterus, and grow into a baby.