Epidemiological, serological immunological and molecular profiles of hepatitis B virus (HBV) IN Nepal

Abstract

Hepatitis B virus (HBV) is a common cause of liver disease and hepatocellular carcinoma. The most common route of transmission being spreading through the blood transfusion and organ transplants. It infects more than 350 million people worldwide. It is estimated that 260,000 individuals are chronically infected with HBV in Nepal and majority of them are unaware of their infection. In this study, epidemiological study was conducted by direct interviewing with all suspectedpatients. The serological study for different antigens and antibody was conducted by Rapid Diagnostic strip test (RDT). Enzymes Linked Immunosorbent Assay (ELISA) was used to confirm this test. Moreover, the molecular test was done by using Real Time PCR for the quantification and genotyping of HBV. Sequence analysis was done by using Sequence analysis software V 5.2 and phylogenetic tree was constructed by neighbor joining method. A total of 500 Nepalese suspected HBV patients were enrolled where 64 % (n=320) werefound to be HBV positive and 36 % (n=180) were HBV negative. This study was donebased on the HBsAg positivity. HBV infection was higher in males (n=213) as comparedwith female (n=106) with male and female ratio of 2.01:1. The most productive agegroups of 20-40 years followed by 40-60 years were found to be associated with the hepatitis B infection. The sero-prevalence rate was higher in province 2 followed by province 3. All the samples recorded positive for HBsAg from ELISA were assayed for Liver function tests (LFT). The level of total bilirubin was found higher in 25.31 % (n=81) patients indicating liver damage. However,the result obtained from the estimation of ALT in HBsAg positivecases showed that 54.69 % (n=197) have elevated level of ALT indicating that these samples seem to have carrier state of the infection. Thrombocytopenia is a common feature of chronic liver disease and was reported in 0.94 % (n=3) of total HBV infected patients.The viral load was found to be highest in chronic HBV patients with HBeAg positive. Genotype D was found to be common among the Nepalese population. HBV sub- genotypes A1,C1,D1,CDand D4 were detected in samples after sequence analysis. Phylogenetic tree showed that genotype-A1 was very closely related to isolates from France and Belgium,Genotype-C1 from Japan,Genotype-D1& D4 from India.CD-recombinant genotype indicated probable divergence of Genotype C to Genotype D or recombinant event might have occurred in S-gene as S-gene determines Genotype. Key Words: Hepatitis B virus (HBV), seroprevalence, LFT, Genotype, Viral load, DNA.