Light microscopic detection of Plasmodium falciparum in vitro through Pf histidine rich protein 2 (HRP 2) gold conjugate labeling: Rapid diagnosis of cerebral malaria in humans

Plasmodium falciparum (Pf) has been found to be the deadliest of all the known species of the parasite\udcapable of infecting humans; this is because it is capable of causing severe cerebral tissue damage.\udThis study was carried out to demonstrate the parasite in the host blood in vitro through immunogold\udlabeling using antibodies against Plasmodium falciparum histidine rich protein 2 (HRP 2); a major\udmetabolite released during the cause of the parasite infection and feeding in the erythrocyte. 12 known\udPf positive samples were obtained from across the six geopolitical zones of Nigeria and were further\udcharacterized by Geimsa thick and thin film for parasite identification parasite count expressed as\udparasites/l of blood. An average of 400 parasites/l of blood was obtained in each of the samples used\udfor this study. Pf-HRP 2 antibody was conjugated to freshly prepared colloidal gold of particle size 40\udnm. The conjugation process was blocked with bovine serum albumin (BSA) and the conjugate itself\udpreserved by 1% glycerol and 0.01% sodium azide. The parasite count was titrated against the Pf-HRP 2\udgold conjugate and was analyzed under the light microscope with a fluorescent filter. Reactivity and\udspecificity of Pf-HRP 2 gold conjugate was found to be highly specific and gave direct identification of\udthe erythrocytes infected with the parasite. A good contrast was also obtained between uninfected\uderythrocytes, parasite and the infected erythrocyte