Integration of hepatitis B virus into patients' sperm genome and its clinical risks

Like the coronavirus disease 2019, the hepatitis B virus is also wreaking havoc worldwide, which has infected over 2 billion people globally. Using an experimental animal model, our previous research observed that the hepatitis B virus genes integrated into human spermatozoa can replicate and express after being transmitted to embryos. However, as of now, this phenomenon has not been confirmed in clinical data from patients.

To explore the integration of the hepatitis B virus into patients' sperm genome and its potential clinical risks.

Forty-eight patients with chronic hepatitis B virus infection were categorized into two groups: Test Group-1 comprised 23 patients without integration of hepatitis B virus DNA within the sperm genome. Test Group-2 comprised 25 patients with integration of hepatitis B virus DNA within the sperm genome. Forty-eight healthy male donors were included as control. The standard semen parameter analysis, real-time polymerase chain reaction, quantitative real-time polymerase chain reaction, sperm chromatin structure assay, fluorescence in situ hybridization, and immunofluorescence assays were utilized.

The difference in the median copy number of hepatitis B virus DNA per mL of sera between Test Group-1 and Group-2 was not statistically significant. In Test Group-2, the integration rate of hepatitis B virus DNA was 0.109%, which showed a significant correlation with the median copy number of hepatitis B virus DNA in motile spermatozoa (1.18 × 10³/mL). Abnormal semen parameters were found in almost all these 25 patients. The integrated hepatitis B virus S, C, X, and P genes were detected to be introduced into sperm-derived embryos through fertilization and retained their function in replication, transcription, and translation.

Our findings suggest that hepatitis B virus infection can lead to sperm quality deterioration and reduced fertilization capacity. Furthermore, viral integration causes instability in the sperm genome, increasing the potential risk of termination, miscarriage, and stillbirth. This study identified an unconventional mode of hepatitis B virus transmission through genes rather than virions. The presence of viral sequences in the embryonic genome poses a risk of liver inflammation and cancer.