Plasmodium falciparum is able to invade erythrocytes through a trypsin-resistant pathway independent of glycophorin B

Infect Immun. 2003 Dec;71(12):6742-6. doi: 10.1128/IAI.71.12.6742-6746.2003.

Abstract

Plasmodium falciparum invades erythrocytes through multiple ligand-receptor interactions, with redundancies in each pathway. One such alternate pathway is the trypsin-resistant pathway that enables P. falciparum to invade trypsin-treated erythrocytes. Previous studies have shown that this trypsin-resistant pathway is dependent on glycophorin B, as P. falciparum strains invade trypsin-digested glycophorin B-deficient erythrocytes at a highly reduced efficiency. Furthermore, in a recent study, the P. falciparum 7G8 strain did not invade glycophorin B-deficient erythrocytes, a finding that was not confirmed in the present study. To analyze the degree of dependence on glycophorin B for invasion by P. falciparum through the trypsin-resistant pathway, we have studied the invasion phenotypes of five parasite strains, 3D7, HB3, Dd2, 7G8, and Indochina I, on trypsin-treated normal and glycophorin B-deficient erythrocytes. Invasion was variably reduced in glycophorin B-deficient erythrocytes. Four strains, 3D7, HB3, Dd2, and Indochina I, invaded trypsin-treated erythrocytes, while invasion by the 7G8 strain was reduced by 90%. Among the four strains, invasion by 3D7, HB3, and Dd2 of trypsin-digested glycophorin B-deficient erythrocytes was further reduced. However, Indochina I invaded trypsin-digested glycophorin B-deficient erythrocytes at the same efficiency as its invasion of trypsin-digested normal erythrocytes. This strongly suggests that the Indochina I strain of P. falciparum is not dependent on glycophorin B to invade through a trypsin-resistant pathway as are the strains 3D7, HB3, and Dd2. Thus, P. falciparum is able to invade erythrocytes through a glycophorin B-independent, trypsin-resistant pathway.

MeSH terms

  • Animals
  • Drug Resistance
  • Erythrocytes / metabolism
  • Erythrocytes / parasitology*
  • Glycophorins / metabolism*
  • Humans
  • Malaria, Falciparum / parasitology
  • Plasmodium falciparum / pathogenicity*
  • Trypsin / metabolism
  • Trypsin / pharmacology

Substances

  • Glycophorins
  • Trypsin