부산대학교 도서관

Background/Aims: Occult HBV infection can persist following HBsAg loss and be transmitted, but the virologicalfeatures are not well defined. Methods: Here we investigated 25 Korean patients who lost HBsAg during follow up, either spontaneously orsubsequent to therapy. Results: Whereas subtype adr (genotype C) was found in 96% of HBsAg positive patients, 75 % of patients wholost HBsAg spontaneously were seemed to be infected with the ayw subtype with sequence similar to genotype D. Mutations in the major hydrophilic region (MHR) of HBsAg were found in 7 patients who lost HBsAg spontaneously. The mutations include T123S, M125I/N, C139R, D144E, V177A, L192F, and W196L, some of which have not been reportedbefore. Functional analysis via transfection experiments indicate that the C139R and D144E mutations drastically reducedHBsAg antigenicity, while the Y225del mutation found in one interferon-treated patient impaired HBsAg secretion. Conclusions: Lack of detectable HBsAg in patient serum could be explained by low level of ccc DNA in liver tissue, lowantigenicity of the surface protein, or its secretion defect.