Human papilloma virus in the sperm cryobank: an emerging problem?

Human papilloma virus (HPV) infection is very common worldwide, but the actual incidence and significance of HPV infection in sperm are poorly understood. In this study, we evaluated the presence of HPV in spermatozoa from thawed semen samples previously stored in our sperm bank. We performed polymerase chain reaction and in situ hybridization for HPV detection in cryovials belonging to 98 oncology patients and in 60 semen samples from healthy controls. Statistical analysis was performed by two-tailed Student's t-test and Fisher's exact test. The frequency of HPV semen infection was 6.1% in thawed cryovials from patients and 3.3% in semen samples from controls. Among the patients, four were found positive for high-risk HPV, one for medium-risk HPV and another for low-risk HPV. Patients had a significantly higher percentage of infected sperm than controls. In conclusion, this report shows the presence of HPV in sperm cells from cryovials of a sperm bank. It is still unclear if HPV-infected sperm are able to cross-contaminate cryovials and impair the outcome of assisted reproduction techniques or to infect partners. Further studies are needed to understand whether screening for HPV should be performed in all semen samples before sperm banking or before intra-cytoplasmic sperm injection procedures.