GB Viruses renamed to Pegiviruses

Despite the similarities in names, all Hepatitis viruses belong to different virus families: Hepatitis A Virus is a Picornavirus, Hepatitis B Virus is a Hepadnavirus, Hepatitis C Virus is a Hepacivirus, Hepatitis D Virus is a Deltavirus and Hepatitis D Virus is a Hepevirus.

Viruses are extremely small in size. So tiny in fact that is very difficult to understand in what family a virus belongs. It is not surprising therefore that some viruses are unclassified or tentatively classified (because nobody has studied them in depth). Therefore, it will not come as a surprise that viruses appear to be in a wrong family or that an entirely new family has to be proposed.

In 1967, it was reported that a surgeon, named George Barker, was suffering from acute hepatitis. When serum from the patient was inoculated into a tamarin monkey (Saguinus spp.), it too developed hepatitis. In ‘honour’ of his being a patient, the virus was designated GB Virus, although has never been proven which specific virus infected Barker.
Searching for further viruses associated with hepatitis, three new viruses were discovered and assigned to the Flaviviridae family in the mid-1990s. These were named the GB Virus-A, GB Virus-B and GB Virus-C/Hepatitis G Virus. A more recent member is GB Virus-D. Hepatitis C Virus is also part of that Flaviviridae family[1].

Of these, GB Virus-B, which is not a human pathogen, is only associated with hepatitis in tamarins, while GB Virus-A, GB Virus-C/Hepatitis G Virus and GB Virus-D in turn, infect primates, humans and frugivorous bats. Hepatitis C Virus and GB Virus-C/Hepatitis G Virus infect Old World primates, while GB Virus-A and GB Virus-B infect New World primates. Natural Hepatitis C Virus infections are limited to humans, although experimental infection of chimpanzees is well documented.

GB Virus-A, GB Virus-C/Hepatitis G Virus and GB Virus-D, unlike GB Virus-B, do not appear to be associated with any signs and symptoms of disease. Moreover, the liver does not appear to be the primary site of replication for GB Virus-A and GB Virus-C/Hepatitis G Virus. Instead, the lymphoid system seems to be their primary target.

Based on the structure of the GB Viruses, it was only recently proposed to classify GB Virus-A, GB Virus-C and GB Virus-D as members of a new fourth genus within the family Flaviviridae, named Pegivirus. The researchers also propose renaming 'GB' viruses within the tentative genus Pegivirus[2].
GBV-B, a member of the genus Hepacivirus with type species HCV, would be renamed GB virus (GBV); this virus is the true GB agent causing acute hepatitis in experimentally infected tamarins. The new genus designation for GBV-A, GBV-C/HGV and GBV-D would be Pegivirus. GBV-A and GBV-A-like viruses would become Simian Pegivirus (SPgV) and species-specific viruses would have the species name in subscripts. GBV-C (or HGV) would become the Human Pegivirus (HPgV), GBV-Ccpz would become SPgVcpz, and GBV-D would become Bat Pegivirus (BPgV). If BPgV isolates found in different bat species segregate by species as with SPgV, the host species will be identified as a subscript.

[1] Epstein et al: Identification of GBV-D, a novel GB-like flavivirus from old world frugivorous bats (Pteropus giganteus) in Bangladesh in PLoS Pathogens - 2010
[2] Stapleton et al: The GB viruses: a review and proposed classification of GBV-A, GBV-C (HGV), and GBV-D in genus Pegivirus within the family Flaviviridae in Journal of General Virology - 2011

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