Hepatitis C virus is now also growing in the lab

New cell system allows for the first time representation of the complete life cycle

Hepatitis C Virus © NIH
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With the help of a new cell system, it is now possible to multiply hepatitis C viruses (HCV) in the laboratory. Scientists in Heidelberg and Tokyo have developed a cell system in which the complete life cycle of HCV - that is from penetration into the cell through propagation inside the cell to the exit of the infected cell - can be displayed in the laboratory.

"This is a milestone in the study of hepatitis C and will provide decisive impetus for further basic research as well as the development of suitable active substances and vaccines against the virus, " explained Professor Ralf Bartenschlager, Director of the Department of Molecular Virology at the University Hospital Heidelberg and the main organizer of the 11th International Symposium "Hepatitis C and Related Viruses" from 3 to 7 October 2004 in Heidelberg.

Infection with HCV is one of the most common causes of chronic hepatitis, cirrhosis and hepatocellular carcinoma (hepatocellular carcinoma) worldwide. In Western Europe around one to two percent of the general population and around 170 million people worldwide are chronically infected with this virus. Liver failure as a result of chronic hepatitis C is now the most common indication for liver transplantation in most industrialized countries.

Despite the declining number of new infections, a further increase in patients with long-term consequences of chronic hepatitis C must be expected for the next 20 to 30 years unless improved therapies are developed.

Active ingredients disrupt the reproductive cycle of the virus

"We need medicines that are more effective and more tolerable than the current forms of therapy with the active ingredients interferon-alpha and ribavirin, " said Drs. Raffaele DeFrancesco, Scientific Director of the Department of Biochemistry of the Instituto Ricerche Biologia Moleculare in Rome. Only about half of all treated patients respond to these drugs. In addition, the therapy often has to be stopped because of the strong side effects. display

The researchers are now focusing on two virus factors (enzymes) that the virus needs to multiply in an infected cell: the so-called polymerase mediates the proliferation of the viral genome. The second target is the protease. It splits proteins and is responsible for the production of virus multiplication factors. The aim is to selectively inhibit these enzymes in the infected cells and thus stop the virus from spreading.

"There are already seven potential HCV drugs in initial clinical trials, " Dr. DeFrancesco, "and we can expect more to follow." However, such studies are tedious and it can take five to seven years for the first effective drugs to become available to the patient for routine use.

Potential vaccines should protect

The vaccine development is also being driven forward, as Dr. Michael Houghton of Chiron Corporation, USA and discoverer of HCV reported. However, potential candidates are not yet in clinical trials. The scientists have high hopes for therapeutic vaccines designed to protect against chronicity. Although the vaccination with such an agent does not prevent the infection, but can protect against the serious long-term consequences. After all, serious liver damage usually only develops many years after the infection, thus presupposing a chronic infection. If it is possible to eliminate the virus from the body in time, the likelihood of liver damage developing is very low. There is currently no vaccine against HCV. This is mainly due to the high variability of the pathogen, which is able to change its relevant properties for the immune response very quickly.

Due to the high demand for research and development in the field of therapy as well as in basic research, there is an annual conference on the topic "Hepatitis C virus and related viruses". Around 650 participants from more than 30 different countries will attend this year's conference.

(University Hospital Heidelberg, 07.10.2004 - NPO)