Temporal evolution and global spread of hepatitis B virus genotype G.

Hepatitis B virus (HBV) infection is considered a major health problem in the world. HBV is classified into genotypes A to J disseminated worldwide. Genotypes A, D and F are the most frequent in the Western World, B and C are predominant in the East, and E, F, H and J are infrequent and restricted to specific regions. HBV-G is a rare genotype, but it has been detected in different continents. This study aimed to report the temporal evolution and global spread of HBV-G comparing whole-genome sequences of this genotype from different regions in the world. Bayesian coalescent analysis was performed to estimate the time to the most recent common ancestor (tMRCA) and the population dynamics in the last decades. The results demonstrated that tMRCA of all HBV-Gs dated back to 1855 (95% highest posterior density interval [HPD 95%]: 1778 - 1931). This genotype has a possible origin in North America and it was disseminated to other continents (South and Central America, Europe, Asia and Africa) more than one century later (around the 1970s). The viral population demonstrated constant spreading from 1855 to the 1980s, followed by an increase in the 1990s and reached a plateau after the 2000s. Wide spreading at the beginning of the 1990s was probably associated with the dissemination by highly sexual active groups and injecting drug users. In conclusion, the present study demonstrated that HBV-G was originated in the 19th century with main events of spread at the end of the 20th century.