-GB virus C (GBV-C) and hepatitis G virus (HGV) are different isolates of the same virus -it is unlikely that GBV-C/HGV is a cause of liver diseases (Zhu et al. 2003) -At least five major genotypes of this virus have been proposed by sequence analysis of the 5' non-coding region (5' NCR) or E2 gene. -Genotype 1 is found mainly in West Africa -Genotype 2 is the most common in the US and Europe -Genotype 3 is frequently observed in parts of Asia -Genotype 4 in samples from Myanmar, Vietnam, and Indonesia -Genotype 5 in South Africa

Viral genomes often contain overlapping genes, as exemplified by the hepatitis B virus. To seek these multifuntional regions this group used comparative sequence analysis on diverse HCV sequences retrieved from GenBank by locating synonymous codons in the standard HCV ORF in which the third position nucleotides are much more conserved than chance alone would predict. The unusual third-base conservation is likely to occur in regions that have novel functions in addition to their known coding function. Ina and colleagues(Ina et al., 1994) suggested that an overlapping gene might constrain the sequence and proposed that translation of a second ORF might be initiated. This group is calling the F protein the alternate reading frame protein (ARFP) and is predicted to play a role in HCV replication, pathogenesis , and carcinogenesis. new software Framesplitter, identified a potential overlapping gene in the core-encoding region of HCV. The presence of this overlapping gene was initially suggested by an unusual degree of sequence conservation in this portion of main ORF. This group analyzed 214 full-length core sequences for regions lacking stop codons and found that majority of these sequences (89%) contain a conserved second open reading frame that is a minimum of 124 codons in lenght. To determine whether F protein is being expressed during HCV infection, patient sera were tested for specific antibodies.