Variants within the "a" determinant of HBs gene in children and adolescents with and without hepatitis B vaccination as part of Thailand's expanded program on immunization (EPI)

Citation
A. Theamboonlers et al., Variants within the "a" determinant of HBs gene in children and adolescents with and without hepatitis B vaccination as part of Thailand's expanded program on immunization (EPI), TOH J EX ME, 193(3), 2001, pp. 197-205
Citations number
31
Categorie Soggetti
Medical Research General Topics
Journal title
TOHOKU JOURNAL OF EXPERIMENTAL MEDICINE
ISSN journal
00408727 → ACNP
Volume
193
Issue
3
Year of publication
2001
Pages
197 - 205
Database
ISI
SICI code
0040-8727(200103)193:3<197:VWT"DO>2.0.ZU;2-G
Abstract
A total of 2229 children selected from five distinct areas of Thailand were screened for HBs antigen (HBsAg) by ELISA. Out of 51, forty-nine HBsAg-pos itive children were further examined for HBV-DNA by the polymerase chain re action, utilizing the region of the hepatitis B Virus (HBV) genome encoding the major antigenic epitopes of hepatitis B surface antigen. Direct automa ted sequencing of the "a" determinant region revealed 11 of 49 children to display variable mutations. The vaccinated and nonvaccinated children had a mino acid variants clustered between residues 120 and 160. Mutations betwee n residues 120 and 160 were found at higher frequency in the vaccinated gro up (4/ 13; 30.8%) than in the nonvaccinated group (7/36; 19.4%), but this w as not statistically significant. Infections with new HBV variants are cont racted either vertically or horizontally within the group having received t he vaccine, a finding confirmed by the presence of amino acid substitutions critical for immune escape. Hence, neither vaccine nor IgG; has any appare nt effect on those variants and the children turn into HBV carriers. Howeve r, the current vaccination program still efficiently protects perinatal tra nsmission of HBV and unless long term studies lead us to conclude otherwise , inclusion of the variant strain(s) into a new vaccine formulation is not deemed necessary.