Comparative analysis of thePlasmodium falciparumhistidine-rich proteins HRP-I, HRP-II and HRP-III in malaria parasites of diverse origin

Abstract

Plasmodium falciparum-infected erythrocytes (IRBC) synthesize 3 histidine-rich proteins: HRP-I or the knob-associated HRP, HRP-II and HRP-III or SHARP. In order to distinguish these proteins immunochemically we prepared monoclonal antibodies which react with HRP-I, HRP-II and HRP-III, and rabbit antisera against synthetic peptides derived from the HRP-II and HRP-III sequences. A comparative analysis of diverse P. falciparum parasites was made using these antibodies and immunoprecipitation or Western blotting. HRP-I (Mr 80,000-115,000) was identified in all knob-positive P. falciparum parasites including isolates examined directly from Gambian patients. However, this protein was of lower abundance in these isolates and in 6 knob-positive, culture-adapted parasites compared to Aotus monkey-adapted parasites or culture-adapted parasites studied previously. HRP-II (Mr 60,000-105,000) was identified in all P. falciparum parasites regardless of knob-phenotype, and was recovered from culture supernatants as a secreted water-soluble protein. Within IRBC, HRP-II was found as a complex of several closely spaced bands. Cell surface radio-iodination of IRBC from several isolates and immunoprecipitation with a rabbit antiserum against the HRP-II repeat sequence identified HRP-II as a surface-exposed protein. Like HRP-I, the abundance of HRP-II was lower in the Gambian isolates than with Aotus monkey-adapted parasites studied earlier. Neither HRP-I nor HRP-II were identified in a knob-positive isolate of P. malariae collected from a Gambian patient. Analogues of these HRP were also absent from asexual parasites of diverse primate and murine malaria species screened with this panel of antibodies. HRP-III (Mr 40,000-55,000) was distinguished by its lower apparent size and by specific reaction with rabbit antibody against its 5-mer repeat sequence. HRP-III was of lowest abundance compared with the other two HRP. These antibody reagents and distinguishing properties should prove useful in studies on the separate functions of the 3 P. falciparum HRP.

Saving Private Ryan: The Indian Scenario (Rapid Diagnosis of Malaria at Regimental Aid Post)

“…It was able to detect parasitemia of very low level (100 parasites/microliter of blood) also very easily. This aspect has been proved by other studies [16,17] and our findings corroborated it. In cases with high clinical suspicion of Pf infection, this test was positive earlier than the detection of parasites in the peripheral smear.…”

Effect of Sequence Variation in Plasmodium falciparum Histidine- Rich Protein 2 on Binding of Specific Monoclonal Antibodies: Implications for Rapid Diagnostic Tests for Malaria

“…3, and a summary of data for the recognition of bands of specific molecular weights is shown in Table 2. The previously reported apparent molecular masses upon polyacrylamide gel electrophoresis of three histidine-rich proteins, knob-associated HRP1 (KAHRP), HRP2, and HRP3, were 80 to 115 kDa, 60 to 115 kDa, and 40 to 55 kDa, respectively (24). As had previously been observed (24), multiple bands were observed by Western blot analysis using HRPspecific MABs.…”

Alteration of coagulation profile in malaria patients and its correlation with degree of parasitemia: a prospective study

“…The newer antigen tests are more objective and can even detect malaria antigen in those whose peripheral smear is negative because of prior anti-malarial treatment. 9 Activation of coagulation cascade occurs even in uncomplicated malaria but this is mild and reverts to normal as patients become afebrile and aparasitemic.…”