title: Identification of occult hepatitis B virus (HBV) infection and viral antigens in healthcare workers who presented low to moderate levels of anti-HBs after HBV vaccination.
abstract: BACKGROUND
  Worldwide, healthcare workers (HCWs) show different levels of response to hepatitis B virus (HBV) vaccine. One of the factors associated with vaccine unresponsiveness may be the existence of current or past HBV infection. Regardless of the presence of HBsAg (overt infection), occult HBV infection (OBI, defined as presence of HBV DNA in the absence of HBsAg) might also account for some non- or hypo-response cases.
  
  
  METHODS
  Sera from 120 HBsAg-negative HCWs with low and moderate levels of anti-HBs, <10 IU/mL (group I) and <100 IU/mL (group II) respectively, were selected and were examined for OBI by sensitive real-time PCR regardless of HBV serological profiles. Direct sequencing on surface genes was carried out in OBI-positive cases.
  
  
  RESULTS
  Four (3.3%) were positive for OBI. All were negative for anti-HBc. Two of the positive cases had moderate levels of anti-HBs (>10 to <100 IU/mL). No significant differences were found between the two groups in terms of risk factors or serological data. No mutations were found in surface proteins of OBI cases.
  
  
  CONCLUSIONS
  OBI in these subjects might be due to other factors rather than presence of "a" determinant mutations. Healthcare workers with inadequate to moderate levels of anti-HBs (<100 IU/mL) following vaccination, regardless of their serological profile for HBV, should be tested for the presence of HBV DNA by sensitive molecular tests. Anti-HBc is not a reliable marker for suspicion of OBI, especially in high-risk group individuals.
authors.affiliation: PhD student, Ms, Department of Infectious Diseases, Faculty of Medicine, Carol Davila University of Medicine and Pharmacy, Bucharest, Romania; Department of Immunology and Department of Virology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Zohreh
authors.initials: Z
authors.lastname: Borzooy
authors.affiliation: MD, PhD, Clinical virologist, Hepatitis B Molecular Laboratory, Department of Virology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Seyed Mohammad
authors.initials: SM
authors.lastname: Jazayeri
authors.affiliation: Ms, PhD, Head of the Department of Pathobiology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Abbass
authors.initials: A
authors.lastname: Mirshafiey
authors.affiliation: Bs, Department of Virology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Azam
authors.initials: A
authors.lastname: Khamseh
authors.affiliation: Bs, Department of Virology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Masoud Karkhaneh
authors.initials: MK
authors.lastname: Mahmoudie
authors.affiliation: Ms, Gastroenterology and Liver Diseases Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Pedram
authors.initials: P
authors.lastname: Azimzadeh
authors.affiliation: Ms, Ministry of Health and Medical Education, Tehran, Iran.
authors.forename: Babak
authors.initials: B
authors.lastname: Geravand
authors.affiliation: MD, Pathologist, Department of Pathology, Tehran Heart Center, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Mohammad Ali
authors.initials: MA
authors.lastname: Boroumand
authors.affiliation: Bs, Tehran University of Medical Sciences, Mirza Kouchak Khan Hospital, Tehran, Iran.
authors.forename: Mina
authors.initials: M
authors.lastname: Afshar
authors.affiliation: Ms, PhD student, Virologist, Department of Virology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Vahdat
authors.initials: V
authors.lastname: Poortahmasebi
authors.affiliation: Ms, PhD, Department of Epidemiology and Biostatistics School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Mostafa
authors.initials: M
authors.lastname: Hosseini
authors.affiliation: MD, PhD, Professor, Department of Infectious Diseases, Carol Davila University of Medicine and Pharmacy, Bucharest, Romania; National Institute of Infectious Diseases, "Prof. Dr. Matei Balş", Bucharest, Romania.
authors.forename: Adrian
authors.initials: A
authors.lastname: Streinu-Cercel
keywords: HBV; HBV vaccine; Healthcare workers; hepatitis B virus