“Immunoenzimatic evaluation of TSSA-II recombinant antigen of Trypanosoma cruzi in sera from naturally infected dogs in an endemic area for Chagas disease, Chaco, Argentina”

CIMINO RC, RAGONE PG, LAUTHIER JJ, MONJE RUMI MM, ALBERTI D´AMATO AM, GIL JF , LÓPEZ QUIROGA I , NASSER J, DIOSQUE P

Armaca Dos Búzios, Rio de Janeiro

Congreso; XXV Meeting of the Brazilian Society of Protozoology-XXXVI Annual Meeting on Basic Research in Chagas Disease; 2009

TSSA (Trypomastigote Small Surface Antigen) protein is found in the surface of the parasite and allows differentiating the two lineages of T. cruzi, Tc I (TSSA I) and Tc II (TSSA II). GST-TSSA II recombinant antigen was evaluated through ELISA technique (0.1µg/well, sera dilution 1/500) using 101 sera from dogs. The following sera groups (G) were formed, G1: 14 positive control sera, corresponding to naturally infected dogs, from which isolates were characterized by MLEE as TcIIe; G2: 60 negative control sera (NC), corresponding to dogs of an endemic area, all negative for xenodiagnostic (Xe), serology and PCR; G3: 18 NC sera, corresponding to dogs of Salta city, not endemic area for T. cruzi, all with negative serology for T. cruzi; G4: 2 dogs sera from which the isolates were characterized by MLEE as TcI; G5: 9 sera with positive serology for T. cruzi and negative Xe, all from the same endemic area. The calculated sensitivity was 85.71% (12/14) with a CI (95%) of 63.81-100; specificity was of 100% (0/78) with a CI of (95%) 99.36-100. Observed concordance was 0.97, Kappa index was 0.91 (CI-95%- 0.78-1.00). The calculated ROC area was of 0.97, EE 0.02; CI (95%) 0.925-1.02 Delong. From G4, 100% was negative. From G5, 66.66% (6/9) were positive and 33.33% (3/9) negative. The concordance between typing test (MLEE) and TSSA-II was almost perfect according to Landis and Koch scale for the interpretation of Kappa index. According to ROC analysis, the test has a high performance for the diagnostic, in the conditions in which it is normatized. The diagnostic capacity of TSSA-II antigen in a sera panel from naturally infected dogs was very good, being an important tool for epidemiological studies of seroprevalence and/or association with Chagas disease.