"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. This evidence together with an analysis of the replicated viral RNA supports a conclusion of viral replication and production."
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, RNA molecules that have enzymatic function and can cleave RNA sequence at specific locations. These two ribozymes were designed to generate the correct ends of the HCV genome and to act as start and stop buttons to gene activity. The construct was "naked," meaning that it contained only nucleic acids, the genetic material of the virus, and did not have the HCV viral envelope, a protective shell of lipids and proteins that surrounds the viral RNA in fully-formed HCV. The naked HCV construct was then placed into human liver cells in a cell culture medium.
Contact: Marcia Vital
NIH/National Institute of Diabetes and Digestive and Kidney Diseases