Expression and characterization of the hepatitis G virus helicase

The hepatitis G virus (HGV) is a new member of the Flaviviridae family and has a genomic organization similar to that of hepatitis C virus (HCV). Protein sequence motifs are present suggesting that HGV encodes a serine proteinase, an RNA-dependent RNA polymerase and a helicase. We have cloned and expressed the putative helicase of HGV and have shown that it contains a poly (U)-stimulated NTPase activity and is able to function as a DNA helicase. Preliminary characterization of the HGV helicase activity reveals similarities with other members of the Flaviviridae, but especially with HCV, raising the possibility that HGV could be used as a surrogate virus for the development of therapies against HCV.