Molecular epidemiology and genetic diversity of hepatitis B virus in Ethiopia

Abstract

Although hepatitis B virus (HBV) infection is hyperendemic in Ethiopia and constitutes a major public health problem, little is known about its genetic diversity, genotypes, and circulation. The aim of this study was to determine the molecular epidemiology and genetic diversity of HBV in Ethiopia, using 391 serum samples collected from HBsAg-positive blood donors living in five different geographic regions. The HBV S/pol gene was amplified, sequenced, and HBV genotypes, subgenotypes, serotypes, and major hydrophilic region (MHR) variants were determined. Phylogenetic analysis of 371 samples (95%) revealed the distribution of genotypes A (78%) and D (22%) in Ethiopia. Further phylogenetic analysis identified one subgenotype (A1) within genotype A, and 4 subgenotypes within genotype D (D1; 1.3%, D2; 55%, D4; 2.5%, and D6; 8.8%). Importantly, 24 isolates (30%) of genotype D formed a novel phylogenetic cluster, distinct from any known D subgenotypes, and two A/D recombinants. Analysis of predicted amino-acid sequences within the HBsAg revealed four serotypes: adw2 (79%), ayw1 (3.1%), ayw2 (7.8%), and ayw3 (11.6%). Subsequent examination of sequences showed that 51 HBV isolates (14%) had mutations in the MHR and 8 isolates (2.2%) in the reverse transcriptase known to confer antiviral resistance. This study provides the first description of HBV genetic diversity in Ethiopia with a predominance of subgenotypes A1 and D2, and also identified HBV isolates that could represent a novel subgenotype. Furthermore, a significant prevalence of HBsAg variants in Ethiopian population is revealed.

A novel hepatitis B virus subgenotype D10 circulating in Ethiopia

“…Twenty‐nine HBV strains, 10 genotype A and 19 genotype D obtained from healthy blood donors, were selected for complete genome sequence analyses from the 371 strains previously investigated . These HBV strains originated from five regions—Addis Ababa (n=11), Adama (n=6), Gondar (n=5), Mekelle (n=6) and Jimma (n=1) (Table ).…”

“…Ethiopia has an intermediate to high HBV endemicity, with HBsAg prevalence of 5.8%‐6.3% in the general population . However, so far there is limited data available regarding the molecular diversity of HBV in this country . Our previous study was limited to the small S gene sequence analysis and several strains remained unclassified.…”

“…Numerous studies carried out in different African countries have also unveiled the emergence of a trend in the geographic distribution of genotypes and subgenotypes. Subgenotype A1 is dominant in Southern, Central and Eastern Africa . Quasi subgenotype A3, previously designated as genotypes A3, A4, A5 and A7, is mainly found in West Africa.…”

“…6,[18][19][20][21][22] Quasi subgenotype A3, 23 previously designated as genotypes A3, A4, A5 and A7, 13,24 is mainly found in West Africa. Subgenotype D1 is the most prevalent subgenotype in North Africa, 18 D2 in Ethiopia, 22 D3 in South Africa, 18 D7 in Tunisia 10 and the recently described D8 in Niger. 9 Genotype E is the most prevalent strain in Central and Western Africa.…”

“…1 However, so far there is limited data available regarding the molecular diversity of HBV in this country. 22 Our previous study was limited to the small S gene sequence analysis and several strains remained unclassified. The aim of this study was to characterize the complete genomes of representative HBV strains of different clades originating from five regions of Ethiopia to classify them into subgenotypes and to gain insight into the molecular diversity and evolution of the strains in circulation.…”