Date of Award

1997

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Biology

Abstract

A cDNA library from in vitro culture forms including metacyclic trypomastigote stages of Trypanosoma cruzi (Tulahuén) was prepared in a γgt 11 vector. The library was screened using serum from a rabbit immunized with irradiated metacyclic stages of T. cruzi to detect clones which produced β-galactosidase fusion proteins bearing epitopes recognized by the metacyclic-specific antiserum. Eleven recombinant bacteriophage clones were excised in vitro , yielding 11 bacterial clones containing recombinant phagemids. Recombinant antigens corresponding to native T. cruzi antigens of 48, 102, and 158 kDa were prepared in Escherichia coli . These recombinant antigens detected parasite specific antibodies in the rabbit metacyclic-specific antiserum. Two of these recombinant antigens, corresponding to the 102 and 158 kDa parasite antigens, detected parasite-specific antibodies in T. cruzi -infected mice during the first week of infection, whereas T. cruzi epimastigote antigen preparations did not detect parasite-specific antibodies until the second week of infection. Immunization of mice with recombinant antigens from the 48, 102, and 158 kDa parasite antigens provided partial protection against challenge infections of T. cruzi LMC medium-derived metacyclic trypomastigote stages. The 48 and 102 kDa parasite antigens appear to be preferentially expressed in metacyclic trypomastigote stages. Evidence was obtained during the course of these studies confirming the presence of a non-specific B lymphocyte blastogenesis in rabbits blastogenesis in rabbits immunized with irradiated LMC medium-derived metacyclic trypomastigotes and in T. cruzi -infected mice and the presence of epitopes shared by E. coli and T. cruzi .

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