La Jolla, CA. April 30, 1999 -- A study published in today's issue of Science by Drs. Luca G. Guidotti and Francis V. Chisari at The Scripps Research Institute (TSRI) demonstrates a new paradigm in viral immunology, namely that the immune system can cure viral infections without destroying the infected cells. Until now, scientists believed that viral clearance was due to the destruction of infected cells by cytotoxic T cells. But the article, "Viral Clearance Without Destruction of Infected Cells During Acute HBV Infection," demonstrates that nondestructive antiviral mechanisms can contribute to viral clearance by eliminating a virus from inside the cell without killing it.

According to Dr. Chisari, Professor, Department of Molecular and Experimental Medicine, and Director, General Clinical Research Center, "The immune system has evolved a defense mechanism that allows it to cure certain viral infections by instructing the infected cells to stop producing virus and to accelerate viral elimination. This appears to be a survival strategy to control infections of vital organs that would be destroyed if the only way to control the infection was to kill all of the infected cells."

Hepatitis B is one of the most common, serious infectious diseases in the world. More than 350 million people worldwide are chronic carriers of the virus (HBV) and it has infected 1-1.25 million Americans. The leading cause of liver cancer, the World Health Organization estimates that the infection leads to more than one million deaths every year. Each year approximately 300,000 people will become infected with the Hepatitis B virus. Although there is a safe and effective vaccine for the prevention of HBV, it is of no value to those already infected. While treatments are currently available for the infection, they have considerable limitations in terms of toxicity and long-term benefits.

In this study, the authors demonstrate that the DNA of the Hepatitis B virus disappears from
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Contact: Robin Goldsmith
rgoldsmi@scripps.edu
619-784-8134
Scripps Research Institute
30-Apr-1999