Abstract
Background Trypanosoma cruzi, the agent of Chagas disease in humans, has a vast reservoir of mammalian hosts in the Americas, and is classified into six genetic lineages, TcI-TcVI, with a possible seventh, TcBat. Elucidating enzootic cycles of the different lineages is important for understanding the ecology of this parasite, the emergence of new outbreaks of Chagas disease and for guiding control strategies. Direct lineage identification by genotyping is hampered by limitations of parasite isolation and culture. An indirect method is to identify lineage-specific serological reactions in infected individuals; here we describe its application with sylvatic Brazilian primates.MethodsSynthetic peptides representing lineage-specific epitopes of the T. cruzi surface protein TSSA were used in ELISA with sera from Atlantic Forest Leontopithecus chrysomelas (golden-headed lion tamarin), L. rosalia (golden lion tamarin), Amazonian Sapajus libidinosus (black-striped capuchin) and Alouatta belzebul (red-handed howler monkey).ResultsThe epitope common to lineages TcII, TcV and TcVI was recognised by sera from 15 of 26 L. chrysomelas and 8 of 13 L. rosalia. For 12 of these serologically identified TcII infections, the identity of the lineage infection was confirmed by genotyping T. cruzi isolates. Of the TcII/TcV/TcVI positive sera 12 of the 15 L. chrysomelas and 2 of the 8 L. rosalia also reacted with the specific epitope restricted to TcV and TcVI. Sera from one of six S. libidinous recognised the TcIV/TcIII epitopes.ConclusionsThis lineage-specific serological surveillance has verified that Atlantic Forest primates are reservoir hosts of at least TcII, and probably TcV and TcVI, commonly associated with severe Chagas disease in the southern cone region of South America. With appropriate reagents, this novel methodology is readily applicable to a wide range of mammal species and reservoir host discovery.
Highlights
Trypanosoma cruzi, the agent of Chagas disease in humans, has a vast reservoir of mammalian hosts in the Americas, and is classified into six genetic lineages, TcI-TcVI, with a possible seventh, TcBat
Lineage-specific TSSA peptide (TSSApep) serology identifies hosts of specific T. cruzi lineages Figure 3 shows an example of T. cruzi lineage-specific ELISA using primate sera, demonstrating the specific nature of the TSSApep recognition
Of those animals that had isolates genotyped as TcII by mini-exon typing (TcII, TcV or TcVI) a high proportion reacted with the epitope common to TcII, TcV and TcVI (11/20 excluding nonspecific reactors) while seven of these 11 reacted with TSSApep-V/VI, representing infection with a hybrid lineage TcV or TcVI
Summary
Trypanosoma cruzi, the agent of Chagas disease in humans, has a vast reservoir of mammalian hosts in the Americas, and is classified into six genetic lineages, TcI-TcVI, with a possible seventh, TcBat. Elucidating enzootic cycles of the different lineages is important for understanding the ecology of this parasite, the emergence of new outbreaks of Chagas disease and for guiding control strategies. Current associations are restricted and fragmentary due to both the scarce sampling in some settings and the difficulty in isolating and genotyping T. cruzi from sylvatic mammals, potentially resulting in an oversimplification or misinterpretation of these lineage-specific findings [7,8,9,10]. It is desirable to identify the mammalian reservoir of these lineages in the Southern Cone region due to their implication in severe human disease in the form of megacolon, megaoesophagus and chagasic cardiomyopathy [7, 13]
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