title: Distribution of hepatitis B virus subgenotype F2a in São Paulo, Brazil.
abstract: BACKGROUND
  HBV genotype F is primarily found in indigenous populations from South America and is classified in four subgenotypes (F1 to F4). Subgenotype F2a is the most common in Brazil among genotype F cases. The aim of this study was to characterize HBV genotype F2a circulating in 16 patients from São Paulo, Brazil. Samples were collected between 2006 and 2012 and sent to Hospital Israelita Albert Einstein. A fragment of 1306 bp partially comprising HBsAg and DNA polymerase coding regions was amplified and sequenced. Viral sequences were genotyped by phylogenetic analysis using reference sequences from GenBank (n=198), including 80 classified as subgenotype F2a. Bayesian Markov chain Monte Carlo simulation implemented in BEAST v.1.5.4 was applied to obtain the best possible estimates using the model of nucleotide substitutions GTR+G+I.
  
  
  RESULTS
  It were identified three groups of sequences of subgenotype F2a: 1) 10 sequences from São Paulo state; 2) 3 sequences from Rio de Janeiro and one from São Paulo states; 3) 8 sequences from the West Amazon Basin.
  
  
  CONCLUSIONS
  These results showing for the first time the distribution of F2a subgenotype in Brazil. The spreading and the dynamic of subgenotype F2a in Brazil requires the study of a higher number of samples from different regions as it is unfold in almost all Brazilian populations studied so far. We cannot infer with certainty the origin of these different groups due to the lack of available sequences. Nevertheless, our data suggest that the common origin of these groups probably occurred a long time ago.
authors.affiliation: Laboratory of Tropical Gastroenterology and Hepatology, Department of Gastroenterology, School of Medicine, University of São Paulo, São Paulo, SP, Brazil. monica.viviana@usp.br.
authors.forename: Mónica V
authors.initials: MV
authors.lastname: Alvarado-Mora
authors.forename: Livia S
authors.initials: LS
authors.lastname: Botelho-Lima
authors.forename: Rubia A
authors.initials: RA
authors.lastname: Santana
authors.forename: Roberta
authors.initials: R
authors.lastname: Sitnik
authors.forename: Paulo Abrão
authors.initials: PA
authors.lastname: Ferreira
authors.forename: Francisco
authors.initials: F
authors.lastname: do Amaral Mello
authors.forename: Cristovão P
authors.initials: CP
authors.lastname: Mangueira
authors.forename: Flair J
authors.initials: FJ
authors.lastname: Carrilho
authors.forename: João R
authors.initials: JR
authors.lastname: Rebello Pinho
mesh_terms: D001499:Bayes Theorem; D001938:Brazil / Q000453:epidemiology; D004279:DNA, Viral / Q000145:classification* / Q000235:genetics; D005260:Female; D005838:Genotype; D006514:Hepatitis B Surface Antigens; D006515:Hepatitis B virus / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification; D019694:Hepatitis B, Chronic / Q000453:epidemiology / Q000821:virology*; D006801:Humans; D008297:Male; D058889:Molecular Typing; D009010:Monte Carlo Method; D010802:Phylogeny; D017422:Sequence Analysis, DNA
chemical_list: D004279:DNA, Viral; D006514:Hepatitis B Surface Antigens