Differentiation of invasive strains of Entamoeba histolytica according to their pathogenicity has been a topic of long debate, but now the pathogenic species only is regarded as E. histolytica while the non-pathogenic species is E. dispar. The present study applied immunoblot to differentiate infections of the two species among microscopically-detected cyst-passers in Korea. The crude extract of E. histolytica separated in 5-20% gradient gels, revealed many fractions of 94, 81, 71, 50, 44, 38.5, 37.5, 29, 19, and 18 kDa when the cysteine proteinase inhibitor, E64, was supplemented. The serum IgG antibody of proven E. histolytica cases reacted with the antigenic fractions of 117, 110, 99, 68, 66, 60, 54, 52, 46, and 45 kDa. Sera of PCR confirmed 3 cases of E. dispar reacted only to the 117 kDa fraction of the E. histolytica crude extract which was regarded as non-specific. To the antigen of monoxenic E. dispar, sera of E. dispar and E. histolytica cases showed the same immunoblot reactions. The serum IgA antibody reacted with several antigenic fractions of both E. histolytica and E. dispar, but IgM and IgE antibodies showed no reaction to either antigen. Sera of 24 symptomless amebic cyst-passers were screened with the E. histolytica antigen; two were found to be infected by E. histolytica and 22 were by E. dispar. The present findings suggest that in Korea most asymptomatic cyst passers of E. histolytica are carriers of E. dispar. Immunoblot using E. histolytica antigen is a good technique for the differentiation of E. histolytica and E. dispar infections.
parasitology-protozoa ; Entamoeba histolytica ; Entamoeba dispar ; immunoblot ; pathogenecity

To observe the antigenic protein fractions in saline extract of Spirometra mansoni plerocercoid (sparganum), the crude extract was separated in reducing conditions of sodium dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-PAGE). The proteins, transferred by electrophoresis to nitrocellulose paper, were reacted with sera from 15 surgically confirmed sparganosis and 24 cysticercosis patients for immunoblotting. Out of 30 identified protein bands in the extract, bands of 29 and 36 kilodaltons (kDa) were the strongest and the most frequently reacting with specific antibody (IgG) in sparganosis sera. Bands of higher molecular weight also reacted with the sera but their frequency of reactions was lower. Sera of cysticercosis reacted with different protein bands in saline extract of sparganum, but the cross reactions were observed in strong antigenic bands of 29 and 36 kDa.
parasitology-helminth-cestoda ; Spirometra mansoni ; plerocercoid ; sparganum ; antigen ; proteins ; sparganosis ; immunoblot ; immunology ; protein