Equine Pegivirus, shortened to EpgV, is the latest member of the only recently created Pegivirus genus. Previously known as GB Virusses, the Pegiviruses constitute a fourth genus within the family Flaviviridae.
Hepatitis C Viruses and Human Pegiviruses (HPgV) belong to two closely related genera of the family Flaviviridae, named Hepacivirus and Pegivirus.
Because the Pegiviruses are 'new', they are now studied more extensively, and more and more variants may be discovered. The viruses genetically most similar to Human Pegiviruses (HPgV) include Simian Pegivirus (SpgV) and Bat Pegivirus (BpgV).
In 2013 a novel family member was discovered in horses Equine Pegivirus (EpgV). Equine Pegivirus seems to cause a chronic subclinical infection, but is not known to be responsible for any specific disease in horses.
 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
 Kapoor et al: Identification of a Pegivirus (GB Virus-Like Virus) That Infects Horses in Journal of Virology - 2013