Occult hepatitis B virus infection in hepatitis B vaccinated children in Taiwan.
OBJECTIVE
Presence of occult HBV infection in HBV vaccinated children remains largely unknown. The aim of this study was to investigate the prevalence of occult HBV infection among HBV vaccinated children in Taiwan.


METHODS
Forty-six HBsAg negative sera from vaccinated children were enrolled randomly. HBV serum markers were detected by ELISA, and the titers of HBV DNA were determined by quantitative real-time PCR. Pre-S, S and pre-core/core genes were amplified by nested PCR and analyzed.


RESULTS
Anti-HBs was detected in 23 (50%) children, and the positivity decreased according to age. Five (10.9%) children were classified into occult HBV infection by positivity of nested PCR in at least two regions; they had a low titer (mean titer 1.60x10(4)copies/ml). Sequence analyses of S gene showed occult isolates were variants; no G145R but C139S vaccine escape mutant was found. Variation and deletion were found in pre-S region; pre-S deletion was more frequent in 3' terminus of pre-S1 which leads to loss of immune epitopes and function sites.


CONCLUSIONS
This pilot study indicates that the prevalence of occult HBV infection is 10.9% in HBV vaccinated children. Since this is a small study, a study of a large population is needed to confirm the findings herein.
Mu
Shu-Chi
SC
Department of Pediatrics, Shin Kong Wu Ho-Su Memorial Hospital, Taipei, Taiwan.
Lin
Yu-Min
YM
Jow
Guey-Mei
GM
Chen
Bing-Fang
BF
D000595:Amino Acid Sequence; D001483:Base Sequence; D002648:Child; D002675:Child, Preschool; D004279:DNA, Viral / Q000097:blood; D005260:Female; D006509:Hepatitis B / Q000453:epidemiology* / Q000517:prevention & control; D006514:Hepatitis B Surface Antigens / Q000097:blood / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D017325:Hepatitis B Vaccines / Q000276:immunology*; D006515:Hepatitis B virus / Q000145:classification / Q000235:genetics; D006801:Humans; D007223:Infant; D008297:Male; D008969:Molecular Sequence Data; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D015995:Prevalence; D011498:Protein Precursors / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D013624:Taiwan / Q000453:epidemiology; D014611:Vaccination
D004279:DNA, Viral; D006514:Hepatitis B Surface Antigens; D017325:Hepatitis B Vaccines; D011498:Protein Precursors; C050807:presurface protein 2, hepatitis B surface antigen