Stable transfection of Trypanosoma cruzi epimastigotes with the trypomastigote-specific complement regulatory protein cDNA confers complement resistance.
Trypanosoma cruzi blood stage trypomastigotes are highly resistant to complement-mediated killing in normal serum. A previously described trypomastigote surface glycoprotein was shown to have binding affinity for human complement components C3b and C4b and restrict activation of the complement cascade, thus preventing lysis of the parasites. Insect stage epimastigotes do not produce detectable levels of this 160-kDa complement regulatory protein (CRP) and are highly sensitive to the lytic effects of complement. Epimastigotes were stably transfected with a T. cruzi expression vector carrying the trypomastigote CRP cDNA and produced fully functional recombinant CRP. The recombinant CRP had binding affinity for C3b, and the transfected epimastigotes were protected from complement-mediated lysis. These results demonstrate for the first time that a developmentally regulated gene of T. cruzi trypomastigotes can be expressed in noninfectious epimastigotes and that production of CRP by epimastigotes is sufficient to confer a virulence-associated trait. Furthermore, these studies demonstrate the critical role that trypomastigote CRP plays in the protection of parasites from the deleterious effects of complement, thus establishing the protein as a virulence factor of T. cruzi.
Norris
K A
KA
Department of Molecular Genetics and Biochemistry, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261, USA. kan1@vms.cis.pitt.edu
D000818:Animals; D002454:Cell Differentiation; D003167:Complement Activation / Q000187:drug effects*; D003179:Complement C3b / Q000378:metabolism; D003169:Complement Inactivator Proteins / Q000096:biosynthesis / Q000235:genetics / Q000494:pharmacology*; D018076:DNA, Complementary / Q000235:genetics; D004351:Drug Resistance; D015870:Gene Expression; D005822:Genetic Vectors; D006801:Humans; D008562:Membrane Glycoproteins / Q000096:biosynthesis / Q000235:genetics / Q000494:pharmacology*; D016133:Polymerase Chain Reaction; D011485:Protein Binding; D015800:Protozoan Proteins / Q000096:biosynthesis / Q000235:genetics / Q000494:pharmacology*; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000494:pharmacology; D014162:Transfection; D014349:Trypanosoma cruzi / Q000166:cytology / Q000235:genetics / Q000276:immunology / Q000472:pathogenicity*
D003169:Complement Inactivator Proteins; D018076:DNA, Complementary; D008562:Membrane Glycoproteins; D015800:Protozoan Proteins; D011994:Recombinant Proteins; C103951:complement regulatory protein, Trypanosoma cruzi; D003179:Complement C3b