HEPATITIS B VIRUS AND ITS GENOTYPES CIRCULATING IN INDIA

Abstract

Hepatitis B virus (HBV), a DNA virus, is responsible for the acute and chronic hepatitis and lever carcinoma. Worldwide, there are 300 to 350 million people are chronically infected with the virus and 6 lac death occur due to chronic hepatitis and HBV associated liver cirrhosis and lever carcinoma. HBV show variable nucleotide diversity in its genome on the basis of which the virus is classied into ten genotypes (A-J). The HBV infection is mainly spread parenterally, and through intimate contacts. HBV infection is manifested as different diseases such as acute hepatitis, chronic hepatitis, acute or spontaneous exacerbation of chronic hepatitis, fulminant hepatitis, liver cirrhosis, hepatocellular carcinoma and hepatic decompensation. The HBV genome is a relaxed circular, partially double stranded DNAof approximately 3,200 base pairs. There are four partially overlapping open reading frames encoding the envelope (pre-S/S), core (pre-core /core), polymerase, and X proteins. The pre-S/S open reading frame encodes the large, middle, and small surface glycoproteins. Pre-core / core open reading frame is translated into pre-core polypeptide which is modied in to a soluble protein, the hepatitis B e antigen (HBeAg), and the nucleocapsid core protein hepatitis B core antigen (HBcAg).