IMMUNOLOGICAL CHARACTERIZATION AND EXPRESSION IN ESCHERICHIA-COLI ANDBACULOVIRUS SYSTEMS OF A TRYPANOSOMA-VIVAX ANTIGEN DETECTED IN THE BLOOD OF INFECTED ANIMALS

A monoclonal antibody (MAb)Tv27 employed in an antigen-detection enzym e immunosorbent assay (Ag-ELISA) for diagnosis of Trypanosoma vivax in fection was shown to react with a T. vivax-specific protein of an appr oximate molecular weight of 10 kDa. This protein is diffusely distribu ted throughout the cytosol and nucleus of metacyclic forms, bloodstrea m forms, and procyclic-like elongated trypomastigotes, but is not dete ctable in epimastigotes of T. vivax. The T. vivax-specific antigen pre pared from parasite lysates appeared to be of lower molecular mass tha n the form expressed in either Escherichia coli or in baculovirus-infe cted silkworm insect cells. In the recombinant baculovirus-infected ce lls, the protein was expressed mostly as an 18-kDa peptide with less a bundant forms of 13 and 12 kDa, while the protein expressed in E. coli was approximately 14 kDa. Both the low- and higher-molecular-weight p roteins are recognized by the MAb Tv27 in Western blots and in Ag-ELIS A. Although the crude preparations of the protein produced by the inse ct cells are labile when kept for more than 2 hr at 24 degrees C, they retained reactivity at temperatures below 4 degrees C for several wee ks. The proteins expressed in both the insect cells and E. coli captur ed anti-T. vivax antibodies in sera prepared from trypanosome-infected animals. Since the recombinant protein expressed in the baculovirus-i nfected cells is available in large homogenous quantities, it would se rve as a positive control in Ag-ELISA and is also usable for antibody detection assays. (C) 1995 Academic Press, Inc.