Presence of human herpes virus 1-thymidine kinase in testis of azoospermic infertile herpes-infected patients

Infection with human herpes virus 1 (HHV1) is a suspected cause of human male infertility. However, the correlation between HHV1 infection and infertility is still unclear. We have previously generated transgenic rats that ectopically express the HHV1 thymidine kinase gene (HHV1-TK) in post-meiotic spermatids and found they had aberrant spermatogenesis and infertility. Therefore, we hypothesized that human infertility might be caused by HHV1 infection. Here, we examined whether HHV1-TK is expressed in human testis by analyzing the presence of its transcript and protein. Specimens were collected by biopsy from 30 azoospermic infertile male patients. RT-PCR and immunohistochemistry showed that 23 patients were positive for HHV1-TK expression, while seven patients were negative. Thus, we demonstrated HHV1-TK expression, indicating HHV1 infection, in the testis of human azoospermic infertile males for the first time; our findings represent a great advancement toward the verification of our hypothesis that HHV1-TK expression might cause human infertility.