ENZYME-LINKED STAINING METHOD FOR LIGHT-MICROSCOPIC DETECTION OF ANTIBODIES TO PARASITE ANTIGENS ON THE MEMBRANE OF PLASMODIUM-FALCIPARUM-INFECTED ERYTHROCYTES

Indirect erythrocyte membrane immunofluorescence (EMIF), a standard me thod for detection of antibodies to the P. falciparum blood stage vacc ine candidate antigen Pf155/RESA, has been adapted to light microscopy by enzyme-linked immunostaining of the erythrocyte membrane, using al kaline phosphatase and chromogenic substrate. This method gives a dark blue staining of the membranes of ring infected erythrocytes. Results obtained with 70 African sera in EMIF and in enzyme immunostaining co rrelated well although the enzyme based method sometimes resulted in h igher antibody titers and appeared to be slightly more sensitive. Simi lar results were obtained when comparing immunofluorescence with enzym e immunostaining for detection of antibodies to intraerythrocytic para site antigens. The enzyme linked immunostaining described is simple an d fast and does not require expensive equipment and should, thus, be w ell suited for use in laboratories with limited resources or under fie ld conditions.