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With great interest we read the article ‘High prevalence of hepatitis E virus in semen of infertile male and causes testis damage’ recently published by Huang et al in GUT.1 The authors report a strikingly high rate of 28% of hepatitis E virus (HEV) RNA PCR positivity (all of them genotype 4 hour) in semen from infertile men from the Chinese Kunming region (n=185) and they could demonstrate HEV antigens in the testes and HEV-RNA in semen of acutely infected macaques.1 This finding is without precedence and has never been reported. Pathophysiologically, the high rate of HEV detection in semen of infertile men could only be explained by HEV persistence beyond the blood-testis barrier.
Duration of PCR positivity in semen has not been assessed by the authors neither in the infertile man nor in the macaques. Thus, it remains unclear whether HEV-RNA persistence in the semen lasts only transiently or for longer periods. Another study already reported that pig semen (various pig farms at the Shaanxi Province, China) could be HEV-RNA positive using nested PCR genotype 4 (GT4).2 In this study the anti-HEV prevalence in the tested pigs was 15.5% (1111/7178), but the prevalence of HEV (genotype 4i) detected in pig semen was lower (1/26, 4%).
The authors of the present publication also previously described a significant detection rate of HEV-RNA in cow milk in the Kunming region, which later could not be confirmed by other studies from China and Europe.3–5 If these discrepancies are related to specific local HEV GT4 strains, local animal housing habits or are laboratory artefacts (pre- or post-analytical) needs still to be resolved.
We wanted to explore whether the European HEV genotype 3 is also associated with male infertility. Therefore, we retrospectively tested stored semen samples (n=79) of infertile men (from a previous study)6 and a prospectively small cohort of patients from our outpatient clinic for male infertility (n=8) for the presence of HEV. Retrospective collection of sperm samples as well as prospective sampling has been approved by the local ethics committee (PV5890). All Volunteers and patients gave written informed consent. The semen was analysed by a sensitive laboratory developed diagnostical quantitative PCR assay (limit of detection 24* IU/ml) on a fully automated real time PCR system (cobas 6800, Roche). The PCR is normalised to the first WHO standard is targeting the conserved open reading frame (ORF)2-3 region of the virus.7 The highly automated process on the cobas 6800 system reduces the risk of sample cross-contamination while HEV-RNA positive full process controls (high and low) in addition to the negative control were run with each PCR batch to ensure overall assay performance throughout the study. Duplex amplification of a full process control in each sample was performed to rule out PCR inhibition in every single sample. Overall, none of 87 samples (0%) tested positive, which is significantly lower than the positivity rate of 28% of the aforementioned study (p<0.001), see figure 1.1
In summary we could not confirm HEV-RNA detection in semen samples from infertile men in Europe, a genotype 3 region. We conclude that extrapolating from the data of our small cohort, no obvious link of HEV genotype 3 infection and male infertility can be conjectured. Our data are in contrast to the reported data from Huang et al.1 A possible explanation for the discrepancy of the findings could that the 4 hour HEV strains detected in the Chinese Kunming region show some special features, possibly caused by genetic variants. Beside this, future studies are needed to proof extrahepatic replication of HEV in the testis of the patients with acute or chronic HEV infection.
Contributors Concept of the study: TH, DV, JS, RL, SR, SF, MA, SS, AL, ML, SP. Acquisition of data: DV, JS, RL, SF. Drafting of manuscript: TH, JS, SP. Reading of manuscript: TH, DV, JS, RL, SR, SF, MA, SS, AL, ML, SP.
Competing interests None declared.
Provenance and peer review Not commissioned; internally peer reviewed.
Patient consent for publication Not required.
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