A partial cDNA clone of trypomastigote decay-accelerating factor (T-DAF), a developmentally regulated complement inhibitor of Trypanosoma cruzi, has genetic and functional similarities to the human complement inhibitor DAF.
Resistance to complement-mediated lysis in Trypanosoma cruzi is due to the expression of complement-regulatory factors by the virulent developmental forms of this protozoan parasite. An 87- to 93-kDa molecule, which we have termed T-DAF (trypomastigote decay-accelerating factor), is present on the surface of the parasite and inhibits complement activation in a manner functionally similar to the mammalian complement regulatory component, decay-accelerating factor. In this report, we characterized monospecific polyclonal and monoclonal antibodies which were obtained from mice and rabbits immunized with fast protein liquid chromatography-purified T-DAF. These polyclonal antibodies were shown to inhibit T-DAF activity and were capable of inducing lysis of the parasites. Both the polyclonal and monoclonal antibodies were used to screen a cDNA expression library prepared from T. cruzi trypomastigote mRNA. From this library, we obtained a partial lambda gt11 cDNA clone which showed genetic and functional similarity to the human C3 convertase inhibitor DAF (A. Nicholson-Weller, J. Burge, D. T. Fearon, P. F. Weller, and K. F. Austen, J. Immunol. 129:184-189, 1982).
Tambourgi
D V
DV
Departamento de Imunologia, Universidade de São Paulo, Brazil.
Kipnis
T L
TL
da Silva
W D
WD
Joiner
K A
KA
Sher
A
A
Heath
S
S
Hall
B F
BF
Ogden
G B
GB
D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D015703:Antigens, CD / Q000235:genetics* / Q000276:immunology / Q000502:physiology; D000953:Antigens, Protozoan; D001483:Base Sequence; D018958:CD55 Antigens; D003001:Cloning, Molecular; D003169:Complement Inactivator Proteins / Q000235:genetics*; D004247:DNA / Q000235:genetics / Q000302:isolation & purification; D006801:Humans; D007106:Immune Sera / Q000276:immunology; D008562:Membrane Glycoproteins / Q000235:genetics* / Q000276:immunology / Q000502:physiology; D051379:Mice; D008969:Molecular Sequence Data; D015800:Protozoan Proteins; D011817:Rabbits; D014349:Trypanosoma cruzi / Q000235:genetics / Q000276:immunology*
D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D000953:Antigens, Protozoan; D018958:CD55 Antigens; D003169:Complement Inactivator Proteins; D007106:Immune Sera; D008562:Membrane Glycoproteins; D015800:Protozoan Proteins; C082910:TDAF protein, Trypanosoma cruzi; D004247:DNA