Hepatitis B virus American genotypes: Pathogenic variants ?

Area of Science:

• Hepatology and Virology
• Genetic Epidemiology
• Viral Hepatitis Research

Background:

• Chronic Hepatitis B virus (HBV) infection causes nearly 900,000 deaths annually from cirrhosis and hepatocellular carcinoma (HCC).
• Ten HBV genotypes (A-J) exist, with genotypes F and H prevalent in the Americas.
• Genotype frequencies correlate with the genetic admixture of American populations, particularly Amerindian ancestry.

Purpose of the Study:

• To review the diversity and frequency of HBV variants in the Americas.
• To evaluate the association between American HBV genotypes/subgenotypes and severe disease progression, including HCC.
• To investigate potential differences in viral mechanisms, such as basal core promoter mutations, contributing to disease severity.

Main Methods:

• Review of existing literature on HBV genotypes and subgenotypes in the Americas.
• Analysis of epidemiological data correlating genotype distribution with population genetic admixture.
• Examination of studies investigating viral factors (e.g., mutations) and their association with disease outcomes like HCC.

Main Results:

• HBV genotypes F and H are the primary autochthonous variants in the Americas, with frequencies linked to Amerindian genetic admixture.
• While methylation patterns showed no significant differences, basal core promoter mutations may be more prevalent in HBV subgenotypes F1b and F2.
• Subgenotypes F1b and F2 appear associated with more severe liver disease progression, potentially leading to HCC, unlike subgenotype F4 and genotype H.

Conclusions:

• Not all American HBV variants exhibit a uniform association with rapid HCC progression.
• HBV subgenotypes F1b and F2 represent a higher risk for severe liver disease compared to F4 and genotype H.
• Further research is needed to fully elucidate the pathogenic mechanisms and clinical implications of different American HBV genotypes and subgenotypes.