title: Characterization of occult hepatitis B virus infection among HIV positive patients in Cameroon.
abstract: OBJECTIVE
  Occult hepatitis B infection (OBI) among HIV positive patients varies widely in different geographic regions. We undertook a study to determine the prevalence of occult hepatitis B infection among HIV infected individuals visiting a health facility in South West Cameroon and characterized occult HBV strains based on sequence analyses.
  
  
  METHODS
  Plasma samples (n = 337), which previously tested negative for hepatitis B surface antigen (HBsAg), were screened for antibodies against hepatitis B core (anti-HBc) and surface (anti-HBs) antigens followed by DNA extraction. A 366 bp region covering the overlapping surface/polymerase gene of HBV was then amplified in a nested PCR and the amplicons sequenced using Sanger sequencing. The resulting sequences were then analyzed for genotypes and for escape and drug resistance mutations.
  
  
  RESULTS
  Twenty samples were HBV DNA positive and were classified as OBI giving a prevalence of 5.9%. Out of these, 9 (45%) were anti-HBs positive, while 10 (52.6%) were anti-HBc positive. Additionally, 2 had dual anti-HBs and anti-HBc reactivity, while 6 had no detectable HBV antibodies. Out of the ten samples that were successfully sequenced, nine were classified as genotype E and one as genotype A. Three sequences possessed mutations associated with lamivudine resistance. We detected a number of mutations within the major hydrophilic region of the surface gene where most immune escape mutations occur.
  
  
  CONCLUSIONS
  Findings from this study show the presence of hepatitis B in patients without any of the HBV serological markers. Further prospective studies are required to determine the risk factors and markers of OBI.
authors.affiliation: HIV/AIDS & Global Health Research Program, Department of Microbiology, University of Venda, Private Bag X5050, Thohoyandou, 0950, Limpopo, South Africa.|Department of Medical Laboratory Sciences, Kenyatta University, Nairobi, Kenya.
authors.forename: George
authors.initials: G
authors.lastname: Gachara
authors.affiliation: HIV/AIDS & Global Health Research Program, Department of Microbiology, University of Venda, Private Bag X5050, Thohoyandou, 0950, Limpopo, South Africa.
authors.forename: Tshifhiwa
authors.initials: T
authors.lastname: Magoro
authors.affiliation: HIV/AIDS & Global Health Research Program, Department of Microbiology, University of Venda, Private Bag X5050, Thohoyandou, 0950, Limpopo, South Africa.
authors.forename: Lufuno
authors.initials: L
authors.lastname: Mavhandu
authors.affiliation: Department of Zoology and Animal Physiology, Faculty of Science, University of Buea, Buea, Cameroon.|Department of Biological Sciences, Higher Teachers' Training College, University of Yaounde, Yaounde, Cameroon.
authors.forename: Emmaculate
authors.initials: E
authors.lastname: Lum
authors.affiliation: Department of Zoology and Animal Physiology, Faculty of Science, University of Buea, Buea, Cameroon.|Department of Medical Laboratory Science, Faculty of Health Sciences, University of Bamenda, Bambili, Bamenda, Cameroon.
authors.forename: Helen K
authors.initials: HK
authors.lastname: Kimbi
authors.affiliation: Department of Biochemistry and Microbiology, Faculty of Science and Agriculture, University of Fort Hare, Alice, South Africa.|Department of Microbiology and Parasitology, University of Buea, Buea, Cameroon.
authors.forename: Roland N
authors.initials: RN
authors.lastname: Ndip
authors.affiliation: HIV/AIDS & Global Health Research Program, Department of Microbiology, University of Venda, Private Bag X5050, Thohoyandou, 0950, Limpopo, South Africa. bessong@univen.ac.za.
authors.forename: Pascal O
authors.initials: PO
authors.lastname: Bessong
mesh_terms: D000293:Adolescent; D000328:Adult; D001483:Base Sequence; D002163:Cameroon / Q000453:epidemiology; D002675:Child, Preschool; D060085:Coinfection / Q000097:blood / Q000453:epidemiology / Q000821:virology; D003430:Cross-Sectional Studies; D004279:DNA, Viral / Q000097:blood; D024882:Drug Resistance, Viral; D005260:Female; D006678:HIV / Q000235:genetics / Q000302:isolation & purification*; D015658:HIV Infections / Q000150:complications / Q000453:epidemiology; D006679:HIV Seropositivity / Q000453:epidemiology* / Q000821:virology*; D006509:Hepatitis B / Q000097:blood / Q000188:drug therapy / Q000453:epidemiology* / Q000821:virology*; D006510:Hepatitis B Antibodies / Q000097:blood; D006512:Hepatitis B Core Antigens / Q000235:genetics; D006514:Hepatitis B Surface Antigens / Q000097:blood / Q000235:genetics; D006515:Hepatitis B virus / Q000235:genetics / Q000302:isolation & purification*; D006801:Humans; D019259:Lamivudine / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D009154:Mutation; D010802:Phylogeny; D015995:Prevalence; D011446:Prospective Studies; D012307:Risk Factors; D017421:Sequence Analysis; D055815:Young Adult
chemical_list: D004279:DNA, Viral; D006510:Hepatitis B Antibodies; D006512:Hepatitis B Core Antigens; D006514:Hepatitis B Surface Antigens; D019259:Lamivudine
keywords: Cameroon; HIV; Hepatitis B virus; Occult hepatitis B infection