Identification of two flavivirus-like genomes in the GB hepatitis agent.

Abstract

A subtractive PCR methodology known as representational difference analysis was used to clone specific nucleotide sequences present in the infectious plasma from a tamarin infected with the GB hepatitis agent. Eleven unique clones were identified, seven of which were examined extensively. All seven clones appeared to be derived from sequences exogenous to the genomes of humans, tamarins, Saccharomyces cerevisiae, and Escherichia coli. In addition, sequences from these clones were not detected in plasma or liver tissue of tamarins prior to their inoculation with the GB agent. These sequences were detected by reverse transcription-PCR in acute-phase plasma of tamarins inoculated with the GB agent. Probes derived from two of the seven clones detected an RNA species of .8.3 kb in the liver of a GB-agent-infected tamarin by Northern blot hybridization. Sequence analysis indicated that five of the seven clones encode polypeptides that possess limited amino acid identity with the nonstructural proteins of hepatitis C virus. Extension of the sequences found in the seven clones revealed that plasma from an infected tamarin contained two RNA molecules >9 kb long. Limited sequence identity with various isolates of hepatitis C virus and the relative positions of putative RNA helicases and RNAdependent RNA polymerases in the predicted protein products of these molecules suggested that the GB agent contains two unique flavivirus-like genomes.

Virus-encoded proteinases of the Flaviviridae.

“…All C termini are arbitrary, but reflect an appropriate region where the alignment is maintained across all the groups of viruses before the similarity drops too low. Sequences used in the analyses : dengue virus (type 1 - Fu et al, 1992 ;type 2 -Hahn et al, 1988 ;type 3 -Osatomi & Sumiyoshi, 1990 ;type 4 -Mackow et al, 1987) ; Japanese encephalitis virus (Sumiyoshi et al, 1987) ; Kunjin virus (Coia et al, 1988) ; Murray Valley encephalitis virus (MVEV -Dalgarno et al, 1986) ; tick-borne encephalitis virus (TBEV -Pletnev et al, 1990) ; West Nile virus (WNV Castle et al, 1986) ; yellow fever virus (YVF - Rice et al, 1985) ; hepatitis G virus (strain GB-A, B - Simons et al, 1995 ;C -Leary et al, 1995) ; hepatitis C virus (HCV strain 1a -Choo et al, 1991 ;1b -Kato et al, 1990 ;1c -Okamoto et al, 1994 ;2a -Okamoto et al, 1991 ;2b -Okamoto et al, 1992 ;2c -Nakao et al, 1996 ;3a -Sakamoto et al, 1994 ;3b -Chayama et al, 1994 ;4a -Chamberlain et al, 1997 a ;5a -Chamberlain et al, 1997 b ;6a -Adams et al, 1997) ; bovine viral diarrhoea virus (BVDV strain Osloss - Renard et al, 1987 ;De Moerlooze et al, 1993 ;NADL -Collet et al, 1988 b ;SD1 -Deng & Brock, 1992 ;NCP7 -Meyers et al, 1996 ;ILLC -Roath & Berry, unpublished ;IIRidpath & Bolin, 1995) ; classical swine fever virus (CSFV strain Alfort -Meyers et al, 1989 ;Brescia -Moorman et al, 1990 . Sequence similarities between NS3 proteolytic domains of the Flaviviridae.…”

Characterization of GB Virus B Polyprotein Processing Reveals the Existence of a Novel 13-kDa Protein with Partial Homology to Hepatitis C Virus p7 Protein

“…We have, therefore, examined whether a p7-like protein is expressed by GB virus B (GBV-B), the most closely related of all animal viruses to HCV. GBV-B was iden-tified in 1995 in a tamarin (Saguinus species) that developed acute hepatitis after inoculation with serum from the 11th tamarin passage of the original, human GB inoculum (16,17). GBV-B infection is typically self-limited and associated with acute hepatitis (18,19), although persistent infection can lead to chronic hepatitis in tamarins (20).…”

Development of a Primary Tamarin Hepatocyte Culture System for GB Virus-B: a Surrogate Model for Hepatitis C Virus

“…HCV infection in humans frequently results in persistent infection with associated disease sequelae, while GBV-B-infected tamarins appear to clear the viral infection with no long-lasting ill effects. However, relatively few animals have been followed long term by reverse transcription-PCR (RT-PCR) since the virus was identified in 1995 (28), and so the potential for a low percentage of chronic infections exists. The acute nature of GBV-B infections in tamarins distinguishes this hepatitis from HCV infections in humans, although the viruses share many characteristics.…”