Researchers block previously unstudied hepatitis B enzyme

A research collaboration between three universities has yielded the ability to measure and block a previously unstudied enzyme of hepatitis B to stop the virus from replicating.

Researchers from Saint Louis University, the University of Pittsburgh and the University of Missouri published an article in the journal PLOS Pathogens on January 24 detailing the breakthrough.

John Tavis, a study author and professor at SLU, said that the study's finding could lead to new drugs to further suppress the deadly virus.

"Hepatitis B is the major cause of liver failure and liver cancer worldwide," Tavis said. "This would have an extremely positive effect on liver disease and liver cancer rates. If we can cure hepatitis B, we can eliminate the majority of liver cancer cases. This research is a step toward achieving that goal."

A person infected with the hepatitis B virus can have as many as one billion viral copies for each drop of blood. To cure a patient, a drug would need to drop those levels to zero. Current medications can reduce the numbers of the virus and make symptoms disappear for years, but for most, the drugs cannot kill the virus completely.

World health experts estimate that as many as 1.2 million people die annually from liver cancer and liver failure developed as a result of hepatitis B.

Tavis and his team developed a way to measure one of two viral enzymes that is vital to hepatitis B's ability to replicate - ribonuclease H. With the ability to measure the RNAseH enzyme, the team was able to find that several effective drugs for HIV treatment also work against the hepatitis B virus.

"I anticipate a new drug targeting (RNAseH) would be used together with the existing drugs," Tavis said. "They jam different parts of the process. The drugs we have are very good drugs. They push the virus down, but they can't quite kill it. They'll still do the heavy lifting in the future, but with an additional drug I hope we'll be able to mop up the rest. Together, they may be able to do it. We don't have a big distance we need to travel to reach that point."

The study was funded by the Saint Louis University Cancer Center, Friends of the Saint Louis University Liver Center and Saint Louis University's President's Research Fund.