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

Date Published: February 20, 2018

Publisher: Public Library of Science

Author(s): Henock Ambachew, Meijuan Zheng, Faustina Pappoe, Jilong Shen, Yuanhong Xu, Jason Blackard.


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.

Partial Text

Hepatitis B virus (HBV) infection remains one of the major worldwide public health burdens. Global estimates suggest that more than 2 billion people have been infected with HBV, and250 million of these people are chronically infected, of which 65 million live in Africa[1–3]. 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]. Prevalence of HBV in Ethiopian blood donors showed marked variations in different parts of the country, with a pooled prevalence of 8.4% [6].

A total of 2,237 blood donors were screened, the sero-positivity for HBV, HIV, HCV, and syphilis were 106(4.7%), 38(1.7%), 11(0.5%), and 11(0.5%), respectively. Of 106 HBsAg sero-positive donors three had co-infection (2HBV-HIV and 1HBV-HCV); these three donors with co-infection were excluded from the study. One hundred three serum samples collected from HBV mono-infected blood donors were used for further laboratory analyses. Majority of the donors (84.5%) were males. The median age of study participants was 25years, with a range of 18 to 55 years. The donors consisted mainly of voluntary donor type and were not receiving HBV antiviral therapy as they responded during the pre-donation interview. In Table 1 baseline characteristics of study participants summarized.

Africa is one of the highly endemic regions of HBV and three genotypes (A, D, and E) have been identified in different countries[3]. HBV genotypic and serologic patterns might help in the designing of management plans, predicting clinical outcomes and updating prevention strategies[43]. Ethiopia is a country with high hepatitis B carrier prevalence and neighbored by countries with variety of HBV genotypes distribution. However, very limited report regarding the molecular study of HBV in Ethiopia was available. Therefore, in this study we determined genotype distribution, mutational pattern and sero-virological profiles of HBV isolates from blood donors in Southern Ethiopia.




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