title: Genotype, serotype, and phylogenetic characterization of the complete genome sequence of hepatitis B virus isolates from Malawian chronic carriers of the virus.
abstract: Hepatitis B virus (HBV) genotypes have distinct geographical distribution. HBV sequences among hepatitis B carriers in Malawi have not been evaluated thus far. HBsAg serotype and genotype of HBV was determined in 20 serum samples from Malawian chronic HBV carriers, and two complete genomes and 13 entire pre-S2/S genes were sequenced directly. Genotype A HBV isolates were found in all of the samples, and serotype with adw2 and ayw2 were detected in three and 17 samples, respectively. In phylogenetic analyses, two complete genomes were classified into a subgroup A' that was described previously in South African isolates of the virus, and were separated from HBV isolates in Western countries with nucleotide differences ranging from 4.1-6.2%. The separation of subgroup A' was also evident in the tree topology of the entire pre-S1/S2, X and precore/core region, but not evident in the small-S region. The nucleotide divergences in subgroup A' were higher than those among genotype A without subgroup A' in the complete genomes as well as each of four open reading frames. All of the 13 pre-S2/S sequences were classified into the subgroup A', and clustered with known HBV isolates with ayw2 in carriers from South Africa and Zimbabwe. Three amino acids in the pre-S2/S gene were characteristic of subgroup A' with ayw2. In conclusion, unique HBV isolates of subgroup A' with ayw2 are prevalent in Malawi, and subgroup A' with a relatively higher nucleotide diversity may be a HBV isolate characteristic of the indigenous population of some African countries.
authors.affiliation: Department of Internal Medicine and Molecular Science, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan.
authors.forename: Fuminaka
authors.initials: F
authors.lastname: Sugauchi
authors.forename: Etsuro
authors.initials: E
authors.lastname: Orito
authors.forename: Hideaki
authors.initials: H
authors.lastname: Kato
authors.forename: Seiji
authors.initials: S
authors.lastname: Suzuki
authors.forename: Saori
authors.initials: S
authors.lastname: Kawakita
authors.forename: Yuko
authors.initials: Y
authors.lastname: Sakamoto
authors.forename: Kouichi
authors.initials: K
authors.lastname: Fukushima
authors.forename: Toshio
authors.initials: T
authors.lastname: Akiba
authors.forename: Namiko
authors.initials: N
authors.lastname: Yoshihara
authors.forename: Ryuzo
authors.initials: R
authors.lastname: Ueda
authors.forename: Masashi
authors.initials: M
authors.lastname: Mizokami
mesh_terms: D000911:Antibodies, Monoclonal; D002353:Carrier State; D004797:Enzyme-Linked Immunosorbent Assay; D014644:Genetic Variation; D016679:Genome, Viral; D005838:Genotype; D006515:Hepatitis B virus / Q000145:classification* / Q000235:genetics; D019694:Hepatitis B, Chronic / Q000150:complications / Q000453:epidemiology / Q000821:virology*; D006801:Humans; D008103:Liver Cirrhosis / Q000821:virology; D010802:Phylogeny; D015995:Prevalence; D017422:Sequence Analysis, DNA; D012703:Serotyping
chemical_list: D000911:Antibodies, Monoclonal