HPgV-2

HPgV-2 (also known as human pegivirus type 2) is the second human pegivirus ever discovered.^[1] It was first identified in 2015 in blood of blood transfusion recipients and initially named hepegivirus 1 because it shared some genetic features with both pegiviruses and hepaciviruses.^[1][2] HPgV-2 was later independently discovered by another group in the blood of a HCV infected patient who had undergone multiple blood transfusions and died from sepsis of unclear etiology. It was then named human pegivirus 2.^[3] HPgV-2 is now classified in the pegivirus genus as part of Pegivirus H species.^[4]

HPgV-2 is a blood-borne virus that causes chronic long term infections much like hepatitis C virus (HCV) and GB virus C (HPgV) – the first human pegivirus to have been discovered – but is not known to be associated with any disease. It usually infects people who are already infected by HCV and has the prevalence of about 1–2% in such persons. Its prevalence in HCV/HIV co-infected subjects is still higher – up to 10%. However its prevalence in the general population in China and USA is very low at 0.1–0.2%.^[1] The chronic infection by HPgV-2 is maintained in presence of anti-envelop antibodies as is the case for HCV chronic infections whereas in case of GB virus C appearance of antibodies usually leads to resolution of the infection.^[5]

HPgV-2 is a positive-sense single-stranded RNA virus with the genome length of about 9,800 nucleotides. Its genomic organization is similar to that of other flaviviruses. It produces a single polyprotein translated from a single open reading frame, which is then cleaved by the viral protease into multiple viral proteins: two structural envelope glycoproteins (E1 and E2), six non-structural proteins (NS2, NS3, NS4A, NS4B, NS5A, and NS5B), a truncated core protein (S, nucleocapsid) and an X protein of unknown function. Different strains of HPgV-2 have sequence homology of 90% or more.^[3]

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