A novel hepatitis B virus (HBV) subgenotype D (D8) strain, resulting from recombination between genotypes D and E, is circulating in Niger along with HBV/E strains

Abstract

Niger is a west African country that is highly endemic for hepatitis B virus (HBV) infection. The seroprevalence for HBV surface antigen (HBsAg) is about 20 %; however, there are no reports on the molecular epidemiology of HBV strains spreading in Niger. In the present study, HBV isolates from the sera of 58 consecutive, asymptomatic, HBsAg-positive blood donors were characterized. Genotype affiliation was determined by amplification, sequencing and phylogenetic analysis of the preS1, polymerase/reverse transcriptase (RT/Pol) and precore (preC)/C regions. The first series of results revealed that different genomic fragments clustered with different genotypes on phylogenetic trees, suggesting recombination events. Twenty-four complete genomic sequences were obtained by amplification and sequencing of seven overlapping regions covering the whole genome, and were studied by extensive phylogenetic analysis. Among them, 20 (83.3 %) were classified unequivocally as genotype E (HBV/E). The remaining four (16.7%) clustered on a distinct branch within HBV/D with strong bootstrap and posterior probability values. Complete molecular characterization of these four strains was achieved by the Simplot program, bootscanning analysis and cloning experiments, and enabled us to identify an HBV/D-E recombinant that formed a new HBV/D subgenotype spreading in Niger, tentatively named D8. Moreover, 20 new complete HBV/E nucleotide sequences were determined that exhibited higher genetic variability than is generally described in Africa. One was found to be a recombinant containing HBV/D sequences in the preS2 and RT/Pol regions. Taken together, these data suggest that, in Niger, genetic variability of HBV strains is still evolving, probably reflecting ancient endemic HBV infection. INTRODUCTIONHepatitis B virus (HBV) infection remains a major public health problem, particularly in Africa, although data for precisely estimating the burden of HBV infection are lacking. It is estimated that 2 billion people worldwide are or have been infected with HBV (WHO: http://www.who. int/csr/disease/hepatitis/HepatitisB_whocdscsrlyo2002_2.pdf), among whom over 360 million are in a chronic carrier state with a high risk of developing cirrhosis and hepatocellular carcinoma (Ganem & Prince, 2004;Lee et al., 1997;Lok, 2004). About 70-140 million of these carriers live in Africa, and about 250 000 of the 1.3 million HBV-related deaths recorded each year throughout the world occur in Africa (Andernach et al., 2009;Hubschen et al., 2008;Kramvis & Kew, 2007;Kramvis et al., 2002;Mulders et al., 2004). HBV belongs to the family Hepadnaviridae and is characterized by a partially double-stranded circular DNA genome of 3These authors contributed equally to this work.The GenBank/EMBL/DDBJ accession numbers for the sequences determined in this study are FN594748-FN594771.A supplementary list of additional GenBank sequences used in this study is available with the online version of this paper. RESULTS Nucleotide sequences and phylogenetic analysesSeveral nucleot...

Hepatitis B Virus (HBV) Infection and Recombination between HBV Genotypes D and E in Asymptomatic Blood Donors from Khartoum, Sudan

“…Subgenotype A3 initially was identified in central Africa and was sporadically reported from west Africa (15,30). HBV genotype E predominates throughout a vast crescent spanning from Senegal to Namibia, one-third of the continent, and extending to the Central African Republic in the east and to Mali and Niger in the north (6,11,18,29). A few HBV/E strains also were identified as minority genotypes further east in Mozambique and Madagascar or further north in Tunisia (21).…”

“…A few HBV/E strains also were identified as minority genotypes further east in Mozambique and Madagascar or further north in Tunisia (21). Finally, HBV genotype D is dominant in northern Africa, with two subgenotypes recently identified in Tunisia (D7) and Niger (D8) (11,26). Sudan is a large country at the presumed geographical junction of the distribution of these three HBV (sub)genotypes.…”

Identification of Novel D11 Hepatitis B Surface Antigen Subgenotype in Jeddah, Kingdom of Saudi Arabia

“…Recently, a complex recombinant of genotypes A, C and G referred to be a new genotype (I) which was described and sequenced in Northwestern China, Vietnam and Brazil changing the genotyping of HBV into nine genotypes confirming with the stereotypes classification (Santos et al, 2010). Subgenotypes have been illustrated in certain HBV genotypes, that is A1-A6 in HBV of genotype A (HBV/A), B1-B8 in HBV/B, C1-C16 in HBV/C and D1-D8 in HBV/D (Kramvis et al, 2002;Chekaraou et al, 2010;Depamede et al, 2009Depamede et al, , 2010.…”

Comparative Assessment between Serological and Molecular Diagnosis for Patients Groups with Hepatitis B Virus

“…Humans are the only known host for HBV, although some nonhuman primates have been infected in laboratory conditions. HBV is relatively resilient and, in some instances, has been shown to remain infectious on environmental surfaces for more than 7 days at room temperature (Abdou et al, 2010). An estimated 2 billion persons worldwide have been infected with HBV, and more than 350 million persons have chronic, lifelong infections.…”