Analysis of molecular diversity of the Trypanosoma cruzi trypomastigote small surface antigen reveals novel epitopes, evidence of positive selection and potential implications for lineage-specific serology.


Bhattacharyya, T; Brooks, J; Yeo, M; Carrasco, HJ; Lewis, MD; Llewellyn, MS; Miles, MA; (2010) Analysis of molecular diversity of the Trypanosoma cruzi trypomastigote small surface antigen reveals novel epitopes, evidence of positive selection and potential implications for lineage-specific serology. International journal for parasitology, 40 (8). pp. 921-8. ISSN 0020-7519 DOI: https://doi.org/10.1016/j.ijpara.2010.01.002

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Abstract

: Chagas disease, marked by life-long chronic infection with Trypanosoma cruzi, remains a major parasitic disease in Latin America. Genetically heterogeneous, T. cruzi is divided into six discrete typing units (DTUs), most recently grouped as TcI-VI. The trypomastigote small surface antigen (TSSA) of T. cruzi has been described as the only known serological marker to identify infection by TcII-VI, as distinct from TcI. Here, by comparative analysis of a cohort of 25 reference strains representing all the known DTUs, we show that TSSA intra-specific diversity is greater than previously reported. Furthermore, TcIII and IV TSSA PCR products are, contrary to expectation, both digested by PvuII, revealing a more nuanced genotyping pattern. Amino acid sequence diversity reveals that the TSSA epitope considered to be serologically characteristic of TcII-VI is restricted to TcII, V and VI, but not of III or IV, and that the diagnostic peptide described as TcI-specific shares key features with TcIII and IV. Notably, TSSA sequences inferred greater phylogenetic affinities of TcIII and IV to TcI than to TcII, V or VI. A high ratio of non-synonymous to synonymous nucleotide substitutions (omega=1.233) indicates that the TSSA gene has been under positive selection pressure. The demonstration of lineage-specific epitopes within TcII-VI has implications for sero-epidemiological studies of Chagas disease based on this antigen.<br/>

Item Type: Article
Faculty and Department: Faculty of Infectious and Tropical Diseases > Dept of Pathogen Molecular Biology
Research Centre: Neglected Tropical Diseases Network
PubMed ID: 20097201
Web of Science ID: 279207900004
URI: http://researchonline.lshtm.ac.uk/id/eprint/4206

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