Invasive amoebiasis can be best diagnosed by -

Option 1,3 Amoebic Lectin Antigen (Gal/NAG lectin) is the principle virulence factor, present on the surface of trophozoites of pathogenic E. histolytica. Its various pathogenic mechanisms are: Adhsion, Cytotoxicity and Complement resistance. Serological tests (ELISA, IHA etc.) become positive only in Invasive amoebiasis. ELISA: detects 170kDa of lectin Ag in stool with 95% sensitivity and specificity. It can also differenciate pathogenic E. histolytica from non pathogenic E. disper (Negative for Lectin Ag). IHA: it uses crude Ag to detect Amoebic Abs (IgG). IgG appears only in the later stage of intestinal amoebiasis. Option 2 Electrophoresis: it is used for Isoenzyme (Zymodeme) analysis. Option 4 Complement fixation test: it is not used in diagnosis of amoebiasis.