Background: Hepatitis B virus (HBV) variants belong to different genotypes, A-J, whose worldwide distribution is\nlinked with geography, probably because viral spread was associated with ancient human migrations.\nHBV genotype G (HBV-G) is an aberrant genotype with little sequence divergence, suggesting a recent origin.\nHBV-G is strongly associated with certain risk groups such as intravenous drug users (IDUs) and men who have sex\nwith men (MSM), but hardly with geography. The origin and epidemiology of HBV-G remain unresolved, as is the\ndisease association.\nMethods: To estimate the prevalence and possible time of introduction of HBV-G into the MSM community in\nAmsterdam, the Netherlands, we have retrospectively analysed 226 blood serum samples from HBsAg positive MSM\nenrolled in the Amsterdam Cohort Studies (ACS) on HIV infection and AIDS dating from 1984 to 1999 using\ngenotype-specific PCR assays.\nResults: Of the 226 HBsAg-positive samples, 149 were HBV DNA positive. Of those, 104 were positive for HBV\ngenotype A (HBV-A) and five for HBV-G, and 40 showed a dual infection with both HBV-A and HBV-G. Being\nHIV-infected was significantly associated with a reduced HBV DNA viral load in blood, but not with the prevalence\nof HBV-G. Early virus already contained stop codons in the precore region and a 36 bp insertion in the core gene\nwhich are the characteristics of HBV-G.\nConclusions: HBV-G was introduced before 1985 into the Amsterdam MSM community. Early isolates show very\nlimited sequence variation, confirming a low evolutionary rate. HBV-G acquisition was independent of HIV infection,\nbut being HIV-infected was significantly associated with a reduced HBV viral load in blood, indicating a beneficial\neffect of early HIV infection in controlling HBV replication.
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