title: High prevalence of occult hepatitis B virus infection in children born to HBsAg-positive mothers despite prophylaxis with hepatitis B vaccination and HBIG.
abstract: OBJECTIVE
  Occult hepatitis B virus (HBV) infection is a well-recognized clinical entity characterized by the detection of HBV DNA in serum and/or liver in the absence of detectable hepatitis B surface antigen (HBsAg). The frequency of the diagnosis depends on the relative sensitivity of both HBsAg and HBV DNA assays. We aimed at determining the prevalence of occult HBV infection in a high risk group of children who developed HBV infection despite immunoprophylaxis.
  
  
  METHODS
  The sera of 75 children born to HBsAg-positive mothers previously immunized by HBIG and prophylaxic vaccine regimen were assayed for HBV DNA by real-time PCR. Subsequently, the samples were tested using a sensitive standard PCR, with an independent set of primers for all HBV genes, and analyzed by direct sequencing.
  
  
  RESULTS
  HBV DNA was detected in 21/75 (28%) children, and ranged between 77 and 9240 copies/ml. All were positive for anti-HBs. Five (24%) children were found to be positive for anti-HBc, while anti-HBc-only positive individuals were not observed. Eight isolates (38%) did not carry any mutation. Thirteen infected children (62%) had at least one mutation in regions known to be involved in functional and/or immune epitope activity. Ten had G145R mutations.
  
  
  CONCLUSIONS
  HBV occult infection seems to be relatively frequent in immunized children born to HBsAg-positive mothers. HBsAg negativity is not sufficient to completely exclude HBV DNA presence. These findings emphasize the importance of considering occult HBV infection in hypo-endemic areas.
authors.affiliation: Hepatitis B Molecular Laboratory, Department of Virology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Sajad
authors.initials: S
authors.lastname: Shahmoradi
authors.forename: Yousef
authors.initials: Y
authors.lastname: Yahyapour
authors.forename: Mahmood
authors.initials: M
authors.lastname: Mahmoodi
authors.forename: Seyed Moayed
authors.initials: SM
authors.lastname: Alavian
authors.forename: Zeinab
authors.initials: Z
authors.lastname: Fazeli
authors.forename: Seyed Mohammad
authors.initials: SM
authors.lastname: Jazayeri
mesh_terms: D016009:Chi-Square Distribution; D002648:Child; D002675:Child, Preschool; D004252:DNA Mutational Analysis; D004279:DNA, Viral / Q000097:blood; D005260:Female; D005838:Genotype; D006509:Hepatitis B / Q000097:blood* / Q000517:prevention & control / Q000635:transmission*; D006514:Hepatitis B Surface Antigens / Q000097:blood*; D017325:Hepatitis B Vaccines / Q000008:administration & dosage; D006515:Hepatitis B virus / Q000235:genetics*; D006801:Humans; D007136:Immunoglobulins / Q000008:administration & dosage; D007223:Infant; D018445:Infectious Disease Transmission, Vertical / Q000517:prevention & control*; D008297:Male; D060888:Real-Time Polymerase Chain Reaction; D012189:Retrospective Studies; D019562:Viral Load
chemical_list: D004279:DNA, Viral; D006514:Hepatitis B Surface Antigens; D017325:Hepatitis B Vaccines; D007136:Immunoglobulins; C045213:hepatitis B hyperimmune globulin