Serotypes and Genotypes of the Hepatitis B Virus in Latin America

Abstract

The World Health Organization has estimated that 2 billion persons are infected with the hepatitis B virus (HBV) with 360 million persons chronically affected. Worldwide, HBV is the causal agent of cirrhosis (30%) and hepatocellular carcinoma (50%). Methods of transmission for HBV are prenatal, percutaneous, and sexual. HBV genotypes, subgenotypes, and subtypes represent genetically stable viral populations that share a separate evolutionary history. Additional instable changes arising from mutations and mutant selection have been observed; these viral subpopulations are HBV variants with medical treatment relevance. Expression of the subtype renders antigenically diverse strains. The same region contains an unknown number of epitopes that define the so-called “a” determinant. Thus, we have two mutually exclusive determinants (d/y, w/r) with four variants (w1-w4 and the expression of a third, q). The difference in 8% of the HBV genome produces different viral groups. Currently, there are ten of these groups (genotypes) classified from A to J, with different geographic distributions. Multiethnic populations present several genotypes and variability is increasing because there are reports of subgenotypes and recombinant intergenotypes, which render the design of effective drugs to combat and eliminate this very difficult virus.