Hepatitis C chimpanzees clear virus after human antiviral treatment
Kyoto University researchers eliminated hepatitis C in six of eight former lab chimpanzees, while finding drug resistance and liver cancer risks.
By Tom Brennan · Health & Medicine Correspondent
3 min read
Human hepatitis C drugs cleared the virus from six of eight hepatitis C chimpanzees at Japan’s Kumamoto Sanctuary, according to a Kyoto University-led team. The finding matters because the animals had acquired long-running infections after earlier biomedical research, and similar treatment had not previously been used to eliminate the virus in chimpanzees for therapeutic purposes.
The results were published in the Journal of Medical Virology. Kyoto University said the work was carried out with Kumamoto University at the sanctuary, which is part of Kyoto University’s Wildlife Research Center and houses chimpanzees formerly used in medical experiments by several Japanese organizations.
Chimpanzees played a role in the discovery of the hepatitis C virus, Kyoto University said. Researchers studying what was then an unidentified pathogen injected it into chimpanzees, work that contributed to the virus being identified in 1989. Since then, medication for people has advanced to the point that hepatitis C can now be nearly cured, the university said.
How were the hepatitis C chimpanzees treated?
The team treated eight chimpanzees with chronic hepatitis C infections that were still alive after an earlier Kyoto University study in 2022. That study had found that infected chimpanzees had poorer health outcomes and shorter lifespans, according to the university.
Two crowdfunding campaigns paid for the human antiviral medication, which Kyoto University described as costly. Before giving the drugs, the researchers used blood tests to assess liver status and decide how long each animal should receive treatment.
The regimen varied by chimpanzee. Three animals received medication for eight weeks, four were treated for 12 weeks, and one was treated for 24 weeks. Because the drugs came as tablets, the team crushed them into powder and mixed them into steamed sweet potato balls or juice.
Researchers checked blood after treatment ended and again six months later. The virus was no longer detected in six chimpanzees, while two still had detectable hepatitis C. Kyoto University said drug-resistance-related mutations may explain why the virus remained in those two animals.
What did researchers find besides viral clearance?
The study also raised concern about liver disease in the infected animals. After the drug courses ended, the team examined the chimpanzees’ livers and found tumors in three of them, according to Kyoto University. Two later died of liver cancer.
Among the chimpanzees that responded to treatment, measures of liver function and health improved, the university said. The researchers described the work as the first successful therapeutic elimination of hepatitis C in chimpanzees.
Hepatitis C is a virus that can persist as a chronic infection and is associated with liver damage. In this study, the researchers followed the infection through blood testing and assessed liver condition to guide treatment and evaluate outcomes.
Satoshi Hirata, the study’s first author, said the work was driven by the health and welfare of the chimpanzees. Kyoto University said Hirata hopes the findings encourage care for other chimpanzees with chronic hepatitis C infections, including animals in Europe and the United States.
This story draws on original reporting from Medical Xpress.