Comparative analysis of the Plasmodium falciparum histidine-rich proteins HRP-I, HRP-II and HRP-III in malaria parasites of diverse origin

Parasitology. 1987 Oct;95 ( Pt 2):209-27. doi: 10.1017/s0031182000057681.

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.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Animals
  • Antibodies, Monoclonal / immunology
  • Electrophoresis, Polyacrylamide Gel
  • Erythrocytes / parasitology
  • Female
  • Fluorescent Antibody Technique
  • Glycoproteins / analysis*
  • Glycoproteins / immunology
  • Humans
  • Immune Sera / immunology
  • Immunoassay
  • Plasmodium falciparum / analysis*
  • Plasmodium falciparum / immunology
  • Plasmodium malariae / analysis
  • Plasmodium malariae / immunology
  • Proteins / analysis*
  • Proteins / immunology

Substances

  • Antibodies, Monoclonal
  • Glycoproteins
  • Immune Sera
  • Proteins
  • histidine-rich proteins