The effects of HPV infection on semen: first results from a new approach.

Study question: The effect of HPV infection on semen characteristics was investigated using a new method that allow to evaluate virus localization in the different semen components. Summary answer: Our data indicate a correlation between HPV infection of exfoliated epithelial cells (from spermatic ducts and accessory glands) and reduction of sperm cell motility. What is known already: HPVs are agents of the most common sexually transmitted diseases. Both in men and in women, HPVs cause a variety of clinical symptoms ranging from warts to cancer. It has been shown (IARC, 2009) that infection with 12 oncogenic HPVs is the major cause of development of cervical cancer in women and it is also related to penile cancers in men. HPV infects epithelial cells and can bind other cell types. Its presence in semen is widely known, but the effects on fertility and reproductive function are still controversial. Study design, size, duration: From January 2015 to December 2015, twenty men were enrolled. From each subject seminal parameters were evaluated according to WHO guidelines. HPV was detected and genotyped both in total semen and in swim up-fraction. HPV detection was performed also in separated semen fractions: sperm cells from total semen and from swim-up and epithelial cells. Semen parameters of positive samples were compared with parameters of negative samples. Moreover, HPV genome wholeness in sperm cells was evaluated. Participants/materials, setting, methods: Partners of women with high-grade squamous intraepithelial lesions. DNA was purified after differential lysis. HPV genotyping was performed by a conventional reverse hybridization and HPV detection in the different semen components was performed by nested PCR with the use of universal primers (MY09 / 11, GP5+ / 6+). HPV genome wholeness was evaluated by Real Time-PCR using six different target genes. Main results and the role of chance: Samples were distributed into HPV positive and negative based on the conventional genotyping (total DNA extraction and reverse hybridization method) or on the new method (differential lysis, DNA extraction from separate fractions and nested PCR method) for every different fraction. In any case, we did not find any statistically significant difference on semen volume, sperm concentration, morphology. On the contrary, only when we compared HPV-positive epithelial cell samples to negative samples in the same fraction, we found a difference in sperm motility. The average percentage of sperm linear progressive motility amounted to 10% ± 11.5 in the positive samples and 54.4% ± 23.3 in the negative samples (two-tailed P value=0.0003). Moreover the HPV genome wholeness was tested by RT-PCR. Results performed on DNA extracted from sperm cells of a sample showed that the copy number of E1 and E2 genes was lower than LCR (Long Control Region) and E6 copy numbers (copy number ratio: 0.4 ± 0.05). These data indicate that in this sample more than half viral genomes are defective, suggesting that a recombination event could be occurred into the sperm heads. Limitations, reasons for caution: Low number of samples because of the sporadic frequency of infection with a single high-risk HPV genotype. Wider implications of the findings: The data support the proposed role of HPV in decreased male and couple fertility. The presence of defective viral genomes rises the idea that these defective forms could be integrated in the sperm genome. In turn, this risk prompts new possible consequences of the viral infection in semen.