Genotyping and sero-virological characterization of hepatitis B virus (HBV) in blood donors, Southern Ethiopia.

Henock Ambachew,Faustina Pappoe,Jilong Shen,Yuanhong Xu,Meijuan Zheng,Jason Blackard

doi:10.1371/journal.pone.0193177

Abstract

Hepatitis B virus (HBV) prevalence is highest in Sub-Saharan Africa including Ethiopia. HBV genotypes have distinct geographic distributions and play a role in course of infection and treatment management. However, in Ethiopia there is paucity of information about distribution of HBV genotypes. This study was done to determine genotype, mutation and sero-virological profiles of HBV isolates in Southern Ethiopia. Cross-sectional, laboratory based study was conducted on 103HBsAg sero-positive samples from a total of 2,237 screened blood donors. HBV serological markers and biochemical assays were done. Serum viral load was measured using quantitative real-time PCR. Partial HBV S-gene was amplified with nested PCR and sequenced. Bioinformatics tools were utilized to determine genotypes, serotypes and mutations. Of 103 HBsAg reactive serum samples, 14.6% and 70.9% were sero-positive for HBeAg and HBeAb, respectively. Ninety-eight samples gave detectable viral load with a median of 3.46(2.62–4.82) log IU/ml. HBeAg sero-positive donors carried elevated levels of viral load. Eighty five isolates were successfully amplified, sequenced and genotyped into 58 (68.2%) genotype A (HBV/A) and 27 (31.8%) genotype D (HBV/D). HBV serotypes found were adw2 (74.1%), ayw2 (24.7%), and ayw3 (1.2%). In twenty-four (28.2%) samples mutations in the major hydrophilic region (MHR) were observed. Donors infected with HBV/A had higher viral load and more frequent MHR mutation than HBV/D infected donors. This study illustrated distribution of HBV genotype A and D among blood donors in southern Ethiopia. It also demonstrated occurrence HBV variants that may influence clinical aspects of HBV infection. The study contributes in narrowing the existing gap of HBV molecular study in Ethiopia.

Highlights

Hepatitis B virus (HBV) infection remains one of the major worldwide public health burdens
Ethiopia is a country with high hepatitis B carrier prevalence and the burden of HBV likely remains significant; its genotype pattern, genetic diversity and mutation analysis is largely unknown
Ethiopia is a country with high hepatitis B carrier prevalence and neighbored by countries with variety of HBV genotypes distribution

Summary

Introduction

Hepatitis B virus (HBV) infection remains one of the major worldwide public health burdens. HBV prevalence is highest in Sub-Saharan Africa and East Asia, where between 5–10% of the adult population is chronically infected. It accounts for 500,000–1.2 million deaths per year and is the tenth leading cause of mortality worldwide[4, 5]. HBV belongs to the Hepadnaviridae family and contain a partially double-stranded circular DNA genome, approximately 3.2kb length. It presents four partially overlapping open reading frames encoding: polymerase, surface, core and X proteins [7,8,9]. The genetic variability has resulted in emergence of ten HBV genotypes (A-J) differ in more than 8% of the genome [13, 14], while forty sub-genotypes differ at least by 4% of the genome [10, 14]

Methods

Results

Conclusion