by The University of Hong Kong
Figure 1. Intranasal inoculation of SARS-CoV-2 causes acute testicular damage in golden Syrian hamsters A. Schema of intranasal challenge of male Syrian hamsters at 8–10 weeks of age. The animals were randomly divided into groups and intranasally challenged by SARS-CoV-2 HK-13 strain at a dose of 10, 102, 103 and 105 PFU in 50ul. The animals were monitored and sacrificed at 1, 4, 7, for study of acute damages, and at 42dpi or 120dpi for chronic damages. B. Sperm counts. The epididymis was dissected and opened, sperms were rinsed out for counting the number per hamster testicle. n=5–10 for each group. Data represent mean ± SD. * p<0.05, ** p<0.01 by Student’s t-test comparing to mock-controls. C. Average weight of testis. After removing the epididymis, the testes were measured for wet weight immediately. n=5-10 for each group. Data represent mean ± SD. D. Representative images of gross pathology of testes from SARS-CoV-2 infected group and mock-controls. The images showed no apparent changes of size and color at 1, 4 or 7dpi comparing to mock-control. Scale bar=1cm. E. Serum concentration of sex hormones determined by ELISA. Serum samples were collected at 1, 4 or 7dpi after 103 or 105 PFU of SARS-CoV-2 HK-13 strain for assays of testosterone and inhibin B. n=5–13 for each group. Data represent mean ± SD. * p<0.05, ** p<0.01 by Student’s t-test comparing to mock-controls. Abbreviations: SARS-CoV-2, Severe Acute Respiratory Syndrome Coronavirus 2; dpi, days post infection; PFU, plaque forming unit. Credit: DOI: 10.1093/cid/ciac142
Researchers at the Department of Microbiology of The University of Hong Kong (HKU) have found that the COVID19 virus can cause acute testicular damage, chronic asymmetric testicular atrophy, and hormonal changes in hamsters despite a light pneumonia.
“In managing convalescent COVID-19 males, it is important to be aware of possible hypogonadism (low sex drive) and subfertility,” said Chair of Infectious Diseases Professor Kwok-yung Yuen, who led the research effort. “COVID-19 vaccination can prevent this complication.” The study has been accepted for publication in the journal Clinical Infectious Diseases.
Previous studies have reported testicular pain in COVID-19 patients. One autopsy study of males who died from COVID-19 showed orchitis with lots of testicular cell damage, but SARS -CoV-2 was not consistently found in semen specimens.
The HKU team investigated the testicular and hormonal changes of hamsters infected by virus given through the intranasal or direct testicular route using the influenza virus in the control group. THe research finds that virus-infected hamsters developed self-limiting pneumonia. But even intranasal SARS-CoV-2 challenge caused acute decrease in sperm count, and serum testosterone starting from the four to seven days. The SARS-CoV-2 infected hamsters developed testicular atrophy with reduced testicular size and weight. The serum sex hormone level was markedly reduced at 42 to 120 days after infection (dpi). Acute testicular inflammation, hemorrhage, and necrosis of seminiferous tubules and disruption of spermatogenesis were seen.
From 7 to 120 dpi, the inflammation, degeneration and necrosis of testicular tissue persisted. Intranasal challenge with omicron and delta variants were found to induce similar testicular changes. These testicular damages can be prevented by vaccination.
The control group of hamsters challenged by influenza A virus given intranasally or intra-testicularly showed no testicular infection or damage.
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