title: HBV NAT positive [corrected] blood donors in the early and late stages of HBV infection: analyses of the window period and kinetics of HBV DNA.
abstract: OBJECTIVE
  The Japanese Red Cross (JRC) carries out nucleic acid amplification testing (NAT) for hepatitis B virus (HBV), hepatitis C virus (HCV) and human immunodeficiency virus-1 (HIV-1) by using a multiplex (MPX) reagent. Screening is undertaken on serologically negative units. In this study we characterized HBV NAT-positive donations individually and analysed the window period and kinetics of HBV DNA, during acute infection, in follow-up studies.
  
  
  METHODS
  Two hundred and seventy-seven HBV DNA-positive donations have been identified in Japan since the introduction of NAT screening of 50-donation minipools. The viral loads and genotypes of these HBV DNA-positive donations were characterized. The doubling time and half-life of HBV was estimated from the data of 123 follow-up donors. The sensitivity of the NAT system (based on 50-donation minipools) was compared with the sensitivities of the enzyme immunoassay (EIA) and the chemiluminescence immunoassay (CLIA). Samples that were CLIA negative, but with > 10(4) copies/ml of HBV DNA, were analysed by sequencing the hepatitis B surface antigen (HBsAg) region.
  
  
  RESULTS
  Out of 277 HBV NAT-positive samples, 125 (45%) were found to have an increasing viral load and 45 (16%) a decreasing viral load. Forty per cent of HBV NAT-positive samples with an increasing viral load, and 33% of those with a decreasing viral load, were negative when tested by using the CLIA. No mutations related to escape mutants were found in the samples that were CLIA negative but with HBV DNA loads of > 10(4) copies/ml. The median HBV doubling time was 2.6 days (n = 93, 1.3-15.2 days) and the half-life was 1.6 days (n = 55, 0.9-6.3 days). Some kinetic difference was observed between genotypes A and B.
  
  
  CONCLUSIONS
  HBV NAT screening detected HBV DNA in both early (the so-called serological window period) and late stages of acute HBV infection.
authors.affiliation: Japanese Red Cross Saitama Blood Center, Hidaka, Saitama, Japan. yoshikawa@saitama.bc.jrc.or.jp
authors.forename: Akira
authors.initials: A
authors.lastname: Yoshikawa
authors.forename: Yuhko
authors.initials: Y
authors.lastname: Gotanda
authors.forename: Masako
authors.initials: M
authors.lastname: Itabashi
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Minegishi
authors.forename: Kimihiro
authors.initials: K
authors.lastname: Kanemitsu
authors.forename: Kusuya
authors.initials: K
authors.lastname: Nishioka
mesh_terms: D001782:Blood Donors; D004279:DNA, Viral; D005838:Genotype; D006509:Hepatitis B / Q000175:diagnosis* / Q000821:virology; D006514:Hepatitis B Surface Antigens / Q000235:genetics; D006515:Hepatitis B virus / Q000235:genetics* / Q000302:isolation & purification / Q000502:physiology; D006801:Humans; D007700:Kinetics; D008403:Mass Screening; D021141:Nucleic Acid Amplification Techniques; D017422:Sequence Analysis, DNA; D013997:Time Factors; D019562:Viral Load; D014779:Virus Replication
chemical_list: D004279:DNA, Viral; D006514:Hepatitis B Surface Antigens