Disease relevance of GB virus B

• Human sera containing antibodies that recognize GBV-A and/or GBV-B recombinant proteins were subjected to polymerase chain reaction studies with degenerate oligonucleotides capable of amplifying a segment of the putative helicase genes from GBV-A, GBV-B or hepatitis C virus [1].
• Functional analyses of GB virus B p13 protein: development of a recombinant GB virus B hepatitis virus with a p7 protein [2].
• Amino acid sequence comparisons of the large polyprotein demonstrate that GBV-Alab is 74% identical to GBV-A and 48% identical to GBV-C, sharing only marginal identity with GBV-B and HCV-1 at 27% [3].
• Phylogenetic analysis and polyprotein organization comparison have shown that GB virus-B (GBV-B) is closely related to hepatitis C virus (HCV) [4].

High impact information on GB virus B

• In vitro studies suggest that GBV-B has an analogous but larger protein (p13) [2].
• However, whereas GBV-B was eliminated from one animal by 20 weeks, the second animal remained viremic (103 to 107 genome equivalents per ml) for >2 years, with alanine transaminase levels becoming elevated again before spontaneous resolution of the infection [5].
• Because an understanding of these events is critical to further development of model GBV-B systems, we characterized signal peptidase processing of the polyprotein segment containing the putative structural proteins [6].
• However, little is known about processing of the GBV-B polyprotein [6].
• Ribavirin induces error-prone replication of GB virus B in primary tamarin hepatocytes [7].

Chemical compound and disease context of GB virus B

• However, several differences in RNA synthesis between the GBV-B and HCV RdRps were observed, including (i) optimal temperatures for activity, (ii) ranges of Mn(2+) concentration tolerated for activity, and (iii) cation requirements for de novo RNA synthesis and terminal transferase activity [8].
• Nonstructural protein 3 (NS3) of GBV-B contains sequence motifs predictive of three enzymatic activities: serine protease, nucleoside triphosphatase (NTPase), and RNA helicase [9].

Anatomical context of GB virus B

• Translation of the HCV polyprotein initiates via an internal ribosome entry site (IRES) and it is proposed that the GBV-B UTR may function in a similar manner [10].

Gene context of GB virus B

• The availability of a recombinant GBV-B virus containing a p7 protein with similarities to the HCV p7 will enhance the relevance of this model and will be of importance for identifying compounds that inhibit p7 function as additional therapeutic agents [2].
• This finding indicates that the 3' limit of the GBV-B IRES is at the initiator AUG and that it does not require downstream polyprotein-coding sequence as suggested for the HCV IRES [11].
• Nucleoside triphosphatase and RNA helicase activities associated with GB virus B nonstructural protein 3 [9].

References