Immuno-enzymatic evaluation of the recombinant TSSA-II protein ofTrypanosoma cruziin dogs and human sera: a tool for epidemiological studies

Abstract

The rTSSA-II (recombinant Trypomastigote Small Surface II) antigen was evaluated by ELISA to detect anti-Trypanosoma cruzi antibodies in sera from naturally infected dogs and humans. For this evaluation ELISA-rTSSA-II was standardized and groups were classified according to the results obtained through xenodiagnosis, ELISA and PCR. Sensitivity (Se), Specificity (Sp), Kappa index (KI) and area under curve (AUC) were determined. The Se was determined by using 14 sera from dogs infected with T. cruzi VI (TcVI) whereas Sp was determined by using 95 non-chagasic sera by xenodiagnosis, ELISA-Homogenate and PCR. The performance of ELISA-rTSSA-II in dog sera was high (AUC=0·93 and KI=0·91). The Se was 92·85% (1 false negative) and Sp was 100%. Two sera from dogs infected with TcI and 1 with TcIII were negative. For patients infected with T. cruzi, reactivity was 87·8% (36/41), there was only 1 indeterminate, and Sp was 100%. Fifty-four sera from non-chagasic and 68 sera from patients with cutaneous leishmaniasis did not react with rTSS-II. ELISA-rTSSA-II showed a high performance when studying sera from naturally infected dogs and it also presented 100% Sp. This assay could be an important tool to carry out sero-epidemiological surveys on the prevalence of T. cruzi circulating lineages in the region.

Evaluation of recombinant antigens of Trypanosoma cruzi to diagnose infection in naturally infected dogs from Chaco region, Argentina

“…Although the performance of different recombinant antigens used to detect human infections have been widely examined and validated , they have been scarcely assessed to diagnose infections in dogs. Furthermore, these few reports are hardly comparable as they have been performed using different techniques, such as: ELISA , Western blot , immunochromatography and trans‐sialidase inhibition assay . When serological techniques are applied to large sample sizes, a versatile, simple and economic technique is needed.…”

“…However, the antigen mixture SAPA/TSSA VI had a significant reactivity (95%) that could be as useful as the protein homogenate of T. cruzi with the advantage of being specific. The specificity of these antigens, compared to other parasite infections, was analysed in humans previously (11,12,17,25,26,28,29,30).…”

“…We worked with the Ags FRA, SAPA, CP1, Ag1 and TSSA VI produced according to the specifications described previously (11,14,17,19).…”

Chagas Disease Diagnostic Applications

“…Serotyping could be a rapid, sensitive, cost-effective and relatively non-invasive alternative to stringent T. cruzi genotyping in humans, and may also be used in animal reservoirs for epidemiological studies (Bhattacharyya et al, 2015; Cimino et al, 2011). Most importantly, development of novel serotyping tools will facilitate the unraveling of possible relationships between parasite genetic variability and clinical features, a major issue in Chagas disease applied research.…”

Lineage-specific serology confirms Brazilian Atlantic forest lion tamarins, Leontopithecus chrysomelas and Leontopithecus rosalia, as reservoir hosts of Trypanosoma cruzi II (TcII)

“…However, the TSSApep-I gave no clear specific reaction with human chagasic sera from TcI endemic regions, potentially due to low immunogenicity or a conformation of the peptide differing from that of the native antigen. Cimino et al [29] have published the only study on lineage-specific serology in naturally infected mammals, demonstrating positive results with an ELISA using E. coli produced recombinant TSSA-II antigen (the epitope shared by TcII, TcV and TcVI) when applied to Argentinian canine sera. Bhattacharyya et al [13] have also applied an expanded range of TSSA epitopes in an ELISA with synthetic lineage-specific peptides and experimentally infected mouse sera, with a pilot study of a small range of sylvatic Brazilian primates.…”