title: Unusual presentation of hepatitis B serological markers in an Amerindian community of Venezuela with a majority of occult cases.
abstract: BACKGROUND
  Occult hepatitis B infection (OBI) is characterized by the presence of hepatitis B virus (HBV) DNA in the absence of HBsAg in the serum of patients. The aim of this study was to characterize HBV infection among a Piaroa community, an Amerindian group which exhibits significant evidence of exposure to HBV but relatively low presence of HBsAg, and to explore the presence of OBI in this population.
  
  
  RESULTS
  Of 150 sera, with 17% anti-HBc and 1.3% HBsAg prevalence, 70 were tested for the presence of HBV DNA. From these, 25 (36%) were found positive for HBV DNA by PCR in the core region. Two of these 25 sera were HBsAg positive, indicating an overt infection. Of the remaining 68 sera tested, 23 exhibited OBI. Of these, 13 were HBV DNA out of 25 anti-HBc positive (52%) and 10 HBV DNA positive, out of 43 anti-HBc negative (23%), with a statistical significance of p = 0.03. Viral DNA and HBsAg were present intermittently in follow up sera of 13 individuals. Sequence analysis in the core region of the amplified DNA products showed that all the strains belonged to HBV genotype F3. The OBI isolates displayed 96-100% nucleotide identity between them. One isolate exhibited the co-circulation of a wild type variant with a variant with a premature stop codon at the core protein, and a variant exhibiting a deletion of 28 amino acids.
  
  
  CONCLUSIONS
  The frequency of OBI found in this Amerindian group warrants further studies in other communities exhibiting different degrees of HBV exposure.
authors.affiliation: Servicio Autónomo: Centro Amazónico para la Investigación y Control de enfermedades Tropicales, Simón Bolívar CAICET, Puerto Ayacucho, Venezuela.
authors.forename: Nathalia E
authors.initials: NE
authors.lastname: Cardona
authors.forename: Carmen L
authors.initials: CL
authors.lastname: Loureiro
authors.forename: Domingo J
authors.initials: DJ
authors.lastname: Garzaro
authors.forename: María C
authors.initials: MC
authors.lastname: Duarte
authors.forename: Daisy M
authors.initials: DM
authors.lastname: García
authors.forename: Milian C
authors.initials: MC
authors.lastname: Pacheco
authors.forename: Isabelle
authors.initials: I
authors.lastname: Chemin
authors.forename: Flor H
authors.initials: FH
authors.lastname: Pujol
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D044467:American Indian or Alaska Native; D000595:Amino Acid Sequence; D015415:Biomarkers / Q000097:blood*; D002648:Child; D002675:Child, Preschool; D005260:Female; D005838:Genotype; D006510:Hepatitis B Antibodies / Q000097:blood* / Q000276:immunology; D006512:Hepatitis B Core Antigens / Q000097:blood* / Q000276:immunology; D006514:Hepatitis B Surface Antigens / Q000097:blood* / Q000276:immunology; D006515:Hepatitis B virus / Q000276:immunology*; D019694:Hepatitis B, Chronic / Q000175:diagnosis / Q000208:ethnology / Q000276:immunology / Q000821:virology*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D015995:Prevalence; D014687:Venezuela / Q000453:epidemiology
chemical_list: D015415:Biomarkers; D006510:Hepatitis B Antibodies; D006512:Hepatitis B Core Antigens; D006514:Hepatitis B Surface Antigens