Cloning and characterization of a gene coding for a protein (KAP) associated with the kinetoplast of epimastigotes and amastigotes of Trypanosoma cruzi.

We have cloned and characterized a gene of Trypanosoma cruzi which encodes a protein, KAP (kinetoplasts-associated protein), expressed in the kinetoplasts of epimastigotes and amastigotes, the replicative stages of the parasite, but not in kinetoplasts of trypomastigotes. The single-copy gene is transcribed into a 3900-nt polyadenylated mRNA. Its trans-splicing acceptor site is preceded by a run of 15 adenosine residues. An open reading frame of 1052 codons is followed by a 3′ untranslated region containing short sequences characteristic of rapidly degradable RNAs. The potential translation product of the KAP gene contains a central region composed of four blocks of repeats of a 9-amino-acid motif. Rabbit antibodies raised against three synthetic peptides containing KAP sequence recognized a 175-kDa protein in epimastigotes and amastigotes which appears by indirect immunofluorescence to be associated with their kinetoplasts. The antibodies do not recognize the kinetoplast of trypomastigotes. The amino terminus of KAP contains features compatible with mitochondrial topogenic sequences.     

Adjuvant-induced arthritis in rats. Evidence that autoimmunity to homologous collagens types I, II, IX and XI is not involved in the pathogenesis of arthritis.

We examined the sera of arthritic outbred Wistar and Sprague-Dawley rats and inbred Fisher 344 and Wistar-Lewis rats for autoantibodies to rat type I, II, IX and XI collagens following the induction of arthritis with mycobacteria (MTB). Although many sera collected over an extended time were assayed in addition to acid eluates of arthritic joints, convincing evidence for autoimmunity to collagen could not be demonstrated. Instead, modest non-specific reactions were observed to collagen, irrelevant proteins, and buffer-treated plastic microtitre wells. In contrast, antibodies to purified protein derivative (PPD) were detected in the sera of rats developing adjuvant-induced arthritis, and antibodies to type II collagen, in the sera and joint eluate of rats developing experimental collagen-induced arthritis. Lastly, delayed-type hypersensitivity responses to collagen could not be detected, nor could adjuvant-induced arthritis be attenuated by soluble collagen injected intravenously before challenge with MTB. We conclude that adjuvant-induced arthritis and experimental collagen-induced arthritis are distinct models of rheumatic disease and that autoimmunity to collagen is neither prevalent in adjuvant-induced arthritis nor necessary for its pathogenesis.