Scientists at the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), one of the National Institutes of Health (NIH), conducted the study.

"Until recently, research on this infectious disease has suffered from the lack of a robust in vitro model system," says T. Jake Liang, M.D., Chief of the Liver Diseases Branch of the NIDDK and co-author of the study. "Our model system produced viral particles that have all the properties of the whole virus."

The NIDDK group used a strain of HCV that would have applications to the greatest number of people - genotype 1, the major type of HCV of human infections worldwide and the type most resistant to current therapies. They constructed an HCV replica using a DNA copy of the original HCV single-strand RNA genome.

They placed the DNA copy between two ribozymes, which were designed to generate the correct ends of the HCV genome and to act as start and stop buttons to gene activity.

The naked HCV construct was then placed into human liver cells in a cell culture medium. Electron microscopy showed evidence of high levels of viral particles resembling fully-formed HCV outside of the human liver cells in the culture medium.

The researchers believe that the HCV construct contained within the human liver cells behaved like a true HCV infection by producing fully formed copies of the virus and releasing them from the host cell into the culture medium. Further testing is needed before the researchers can determine if the viral particles produced in this system are in fact infectious.

"With this cell-based system, we can screen compounds with a cell-based assay to look for inhibitors of virus replication," says Liang. "We can also apply this technique to develop model systems for other similar viruses."; Source: NIH/National Institute of Diabetes and Digestive and Kidney Diseases