Detection of Human Herpesviruses (HHVs) in Semen of Human Male Infertile Patients

Abstract

Recently we demonstrated an ectopic expression of the human herpesvirus 1 thymidine kinase (HHV1-TK) gene by functioning of an intrinsic endogenous promoter in the transgenic rat (TG-rat), suggesting that HHV1 infection in humans induces expression of the TK gene with the ectopic promoter in the testis and results in accumulation of HHV1-TK protein, triggering male infertility similar to that in the TG-rat. Hence, in this study, we started to investigate a relationship between infection of herpesvirus and human male infertility. Semen was donated by Chinese male infertile patients (153 men, aged 21–49 years) with informed consent, followed by DNA preparation and analysis by PCR and DNA sequencing. Semen volume, sperm number and density, and sperm motility were examined. DNAs of HHV1, HHV4, HHV5 and HHV6 were confirmed by PCR, electrophoresis and DNA sequencing. Finally, virus DNA was identified in 59 patients (39%). The number of carriers was 39 (25%) for HHV1, 6 (4%) for HHV4, 33 (22%) for HHV5 and 3 (2%) for HHV6, respectively. Moreover, double-infection was found in 22 out of 59 specimens (37%), most of which were double-infection of HHV1 and HHV5 (15 out of 22 carriers). Though slight severity was present in some of the carriers, the relationship between virus infection and sperm impairment was not conclusive. Accordingly, it is essential to examine whether the viral HHV1-TK gene is expressed in the testis of the infertile human HHV carrier.

Ectopic Expression of Human Herpesvirus 1 Thymidine Kinase Induces Male Infertility

“…Recently, a number of studies have detected HHVs in the semen and/or spermatozoa of ∼90% of infertile male patients, although regional variations must be taken into account (Table 2) [6,[9][10][11][21][22][23][24][25][26][27][28][29][30][31]. Many investigators have tried to confirm the relationship between male infertility and HHVs infection by combining viral infection rates with statistical analysis of semen and/ or sperm samples derived from PCR-based viral DNA analysis, antigen-antibody reaction, and immunocytochemistry of spermatozoa.…”

“…Analysis of oligozoospermia rates between viral DNA-negative (36 patients) and -positive (39 patients) according to WHO Guidelines (5th edition). Reproduced and modified from [21] with permission from the Society for Reproduction and Development.…”

“…Viral sequences are shown below the nucleotide sequence. Reproduced and modified from[21] with permission from the Society for Reproduction and Development.…”

Seminal shedding of human herpesviruses

“…The majority of these studies report a prevalence of approximately 6% in men from Germany, North America, France, Africa, Greece, Denmark, Australia, and Russia (Table 1). In contrast, several studies on semen of fertility-clinic attendants from China, Taiwan, Spain, and Greece, have reported high prevalences of HCMV between 21.6% to 56.9% [14,22,23,38,40]. This could possibly be explained by geographic variation, however another study from Greece, also of semen from fertility-clinic attendants, found HCMV in only 7.1% [17].…”

“…Bezold et al found the prevalence to be 4.0% in a German population of infertility patients [11] and 3.7% in a population of American infertility patients [12]. Chen et al found HHV-6A/B in 2.0% of infertility patients from China [14], whereas Michou et al detected HHV-6A/B in 8.2% of 109 men from couples undergoing IVF treatment in Spain [22]. A slightly higher prevalence of 13.5% was seen by Kaspersen et al in semen from Danish sperm donors [18] (Table 2), suggesting that the prevalence of HHV-6A/B is not increased among patients attending a fertility clinic.…”