Hepatitis E is an infectious disease of the liver found across the globe. It is caused by the hepatitis E virus and in most cases heals by itself. However, in patients with a suppressed immune system, e.g. because of a transplant, the HEV infection may become chronic and after only a few years lead to cirrhosis of the liver. The DZIF scientists PD Dr. Sven Pischke and Dr. Thomas Horvatits of the Hamburg-Eppendorf University Medical Center (UKE), Germany, made an observation in just these chronically infected patients: despite antiviral treatment and an initially reduced virus concentration in the blood, the viral hepatitis E was reactivated. The reasons for this were investigated by Sven Pischke, Thomas Horvatits and their team in cooperation with Prof. Dr. Eike Steinmann (Ruhr University Bochum), Prof. Reimar Johne (German Federal Institute for Risk Assessment [BfR]) and their colleagues in a pilot study published in the Journal of Hepatology. They established that hepatitis E viruses survived much longer in the ejaculate of chronically infected men than in their serum.
In their study, Pischke and Horvatits thus used electron microscopy, polymerase chain reaction, density gradient centrifugation and genome sequencing to examine the blood, urine, stool and ejaculate of a total of nine hepatitis E patients, three of these immunosuppressed patients with chronic viral hepatitis E and six further subjects with an intact immune system and an acute hepatitis E infection. In two of the three chronically infected patients, a significantly higher viral load was found in the ejaculate than in the blood. Under treatment with the antiviral medication ribavirin, no hepatitis E viruses could be detected in the blood, but were detected in the ejaculate. In the further course, the virus load in the serum, ejaculate and stool again increased rapidly - a possible indication of a reactivation of the hepatitis E infection affecting the entire body. By contrast, in none of the six immunocompetent patients with acute hepatitis E was HEV found in the ejaculate, a potential virus reservoir.
“Evolution has achieved impermeability of the blood-testis barrier to cells of the immune system and to harmful substances,” explains Sven Pischke. “When patients with a weakened immune defence become infected with hepatitis E, the virus can pass this barrier unhindered and remain in the male gonads. In this instance, the blood-testis barrier is disadvantageous for the patients because immune cells cannot pass into the testes in order to fight the pathogens there,” Pischke continues.
Is a hepatitis E infection sexually transmissible?
Normally, an infection with hepatitis E viruses is transmitted through polluted water or contaminated food, e.g. the consumption of insufficiently cooked pork or game meat. Whether chronically infected hepatitis E patients are infectious for their sexual partners by way of their ejaculate will be the subject of further studies in the animal model. Until that has been clarified, the ejaculate of hepatitis E patients will be clinically tested.
The current study has been conducted within the framework of the German Center for Infection Research (DZIF) at the University Medical Center Hamburg-Eppendorf (PD Dr. Pischke) and at the Ruhr University Bochum (Prof. Dr. Steinmann). Dr. Thomas Horvatits is currently supported with a DZIF-Clinical-Leave stipend. PD Dr. Sven Pischke is also a stipend holder of the Else Kröner-Fresenius Foundation.