AIM:ToelucidatethemolecularmechanismsunderlyinghepatitisBvirus(HBV)occultinfectionofgenotypeC.METHODS:Atotalof10typesofhepatitisBsurfaceantigen(HBsAg)variantsfromaKoreanoccultcohortwereused.AfteracompleteHBVgenomeplasmidmutatedsuchthatitdoesnotexpressHBsAgandplasmidencoding,eachHBsAgvariantwastransientlyco-transfectedintoHuH-7cells.ThesecretioncapacityandintracellularexpressionoftheHBVvirionsandHBsAgsintheirrespectivevariantswereanalyzedusingreal-timequantitativepolymerasechainreactionassaysandcommercialHBsAgenzyme-linkedimmunosorbentassays,respectively.RESULTS:AllvariantsexhibitedlowerlevelsofHBsAgsecretionintothemediumcomparedwiththewildtype.Inparticular,ineightofthetenvariants,verylowlevelsofHBsAgsecretionthatweresimilartothenegativecontrolweredetected.Incontrast,mostvariants(9/10)exhibitednormalvirionsecretioncapacitiescomparablewith,orevenhigherthan,thewildtype.ThisprovidednewinsightintotheintrinsicnatureofoccultHBVinfection,whichleadstoHBsAgsero-negativenessbuthashorizontalinfectivity.Furthermore,mostvariantsgeneratedhigherreactiveoxidativespeciesproductionthanthewildtype.ThisfindingprovidespotentiallinksbetweenoccultHBVinfectionandliverdiseaseprogression.CONCLUSION:ThepresentlyobtaineddataindicatethatdeficiencyinthesecretioncapacityofHBsAgvariantsmayhaveapivotalfunctionintheoccultinfectionsofHBVgenotypeC.
