EXPRESSION OF TRYPANOSOMA-CONGOLENSE ANTIGENS IN SPODOPTERA-FRUGIPERDA INSECT CELLS

Transcripts which encode two metacyclic-form-specific variable surface glycoproteins (mVSGs) of Trypanosoma congolense IL3000 have been clon ed into baculovirus expression vectors using a novel transfer vector, pAcL11. One of the recombinant baculoviruses (AcVSG1) expressed a mVSG as a glycoprotein with a signal peptide which was cleaved in this exp ression system, whereas the other one (AcVSG2) expressed an unprocesse d protein. From 1 liter of culture containing 10(9) Spodoptera frugipe rda cells infected with the recombinant baculoviruses, 10 and 30 mg of mVSG1 and mVSG2, respectively, were obtained. Monospecific polyclonal antibodies produced by immunization of mice with the recombinant prot eins reacted specifically with the respective proteins and showed no c ross-reactivities between mVSG1 and mVSG2 in immunoblot assays. The an tibodies to each of the proteins stained only the surface of a proport ion of intact fixed T. congolense IL3000 metacyclic forms. It was poss ible to determine from these studies that, on the average, the parasit es expressing mVSG1 constitute approximately 45% of the metacyclic pop ulation of T. congolense IL3000 maintained in in vitro cultures, where as those that express mVSG2 constitute approximately 20%. (C) 1995 Aca demic Press, Inc.