ANTIGENS SHARED BY LEISHMANIA SPECIES AND TRYPANOSOMA-CRUZI - IMMUNOLOGICAL COMPARISON OF THE ACIDIC RIBOSOMAL P0 PROTEINS

Patients with visceral leishmaniasis produce high levels of immunoglob ulin, but the specificities of antibodies produced are not well charac terized. In an effort to identify leishmania antigens that are specifi c to Leishmania species or are cross-reactive with other parasitic pro tozoa, we have cloned and characterized full-length genomic and cDNA c lones encoding a Leishmania chagasi acidic ribosomal antigen, LcP0, re cognized during human infections. The protein is homologous to the Try panosoma cruzi and human ribosomal proteins TcP0 and HuP0, respectivel y. Unlike most higher eukaryotes, but similar to TcP0, LcP0 has a C-te rminal heptapeptide sequence resembling those of the archaebacterial a cidic (P-like) proteins. The highly charged C-terminal acidic domain o f LcP0 contains a serine residue typically found in most eukaryotes bu t lacking in all T. cruzi P proteins we have characterized thus far. L . chagasi-infected individuals as well as those with T. cruzi infectio ns have antibodies cross-reactive,vith recombinant LcP0 and TcP0 as we ll as HuP0. However, the properties of anti-P0 antibodies in T. cruzi and L. chagasi infection sera are quite different. Through the use of synthetic peptides, we showed that while T. cruzi infection anti-TcP0 antibodies are exclusively directed against the C-terminal domain of T cP0, L. chagasi infection sera contain antibodies reactive with epitop es other than the C-terminal sequence of LcP0. Thus, anti-LcP0 antibod ies in L. chagasi infection sera represent the first characterized dev iation from the restricted immunodominant C-terminal epitope involved in the generation of anti-P0 antibodies following infection or autoimm une diseases.