Hepatitis B is a worldwide healthcare problem, especially in developing areas. An estimated one-third of the global population has been infected with this virus; approximately 350 million people are lifelong carriers, and only 2% spontaneously seroconvert annually. Hepatitis B virus (HBV) belongs to the hepadnavirus family of enveloped DNA viruses containing a partially double-stranded genome of 3182 ± 3221 bp depending on the genotype that encodes four overlapping open reading frames. HBV is classified into eight genotypes (A–H) that are geographically dispersed. Genotype A is predominant in North America, Western Europe, and Africa; genotypes B and C in Asia; genotype D in Southern Europe, Africa, and India; genotype E in West Africa; genotype F in Central and South America and Alaska; genotype G has been found in the United States, France, and Germany; and genotype H in Central America. Genotypes A, B, C, and D predominate in the United States, while the other genotypes are less common. Further detailed analysis of these HBsAg variants would provide further understanding of the antigenic structure of HBV.
Part of the book: Hepatitis B and C