A new study from The Ohio State University has found that the hepatitis E virus (HEV) can attach to sperm in pigs, suggesting the virus might be sexually transmitted and could play a role in male infertility.
Hepatitis E is a major cause of acute viral liver infections in people, especially in developing countries with poor sanitation. In the United States, the virus is also commonly found in pigs. Although it is usually located in organs rather than meat, it is killed by cooking.
HEV has already been linked to serious pregnancy complications and reports of male infertility. Because pig reproductive systems are similar to humans, researchers used pigs to explore how the virus behaves in the body.
After infecting pigs with HEV, the researchers found the virus in the animals’ blood and feces, confirming infection even though the pigs showed no symptoms — a common feature of HEV in humans as well. More importantly, the virus was found on the head of sperm cells. These same viral particles were also able to infect and reproduce in human liver cells in the lab.
“This is the first study to show a clear link between hepatitis E virus and sperm cells,” said lead author Kush Yadav, who completed the research as a PhD student at Ohio State’s Center for Food Animal Health. “Next, we want to understand how this interaction happens and whether the virus can be passed through sex.”
The study, published in PLOS Pathogens, also raises questions about how HEV may survive in the body. Some viruses can hide in the testicles, protected by the blood-testis barrier, which shields them from the immune system. HEV has also been associated with pancreatic and neurological disorders in people. Until now, it was thought to spread mainly through fecal contamination.
Senior researcher Scott Kenney, an associate professor at Ohio State, said the findings were part of a broader investigation into HEV in pigs, especially strains resistant to antiviral drugs.
In the new study, researchers used fluorescent imaging to analyze semen from pigs 84 days after infection. They found HEV particles in about 19% of sperm cells. While they’re not yet sure whether the virus enters the sperm or clings to the outside, the team believes sperm may act as carriers rather than being infected themselves.
The presence of HEV was also linked to damaged sperm that moved poorly, though the study couldn’t confirm if this led to infertility. Still, since HEV has been associated with fertility issues in humans, the connection is concerning.
Yadav said the research may eventually lead to screening the sexual partners of pregnant women who test positive for HEV, though more evidence is needed to confirm sexual transmission.
There are also potential consequences for the pork industry. Most commercial pig breeding uses artificial insemination, and sperm from donor pigs is widely distributed. This raises concerns that infected sperm could be spreading HEV between farms.
“Because HEV doesn’t visibly harm pigs or reduce profits, the swine industry may not invest in widespread vaccination,” Kenney said. “But low-cost screening or targeted vaccination at breeding facilities could help stop the virus from spreading.”
The research was supported by state and federal funding to the Ohio Agricultural Research and Development Center and by the National Institute of Allergy and Infectious Diseases.
Co-authors include researchers from Ohio State and the College of Wooster.
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