a four-fold or greater increase of antibody in patients have an acute influenza a virus infection , were found in igg1 ( all 10 cases ) , igg3 ( seven cases ) , igg4 ( eight cases ) and in iga1 ( six cases ) whereas igg2 and igm responses were observed only in one and three cases , respectively .
C0003241
antibody
C0020860
igg4