An improved serodiagnostic test for Chagas' disease employing a mixture of Trypanosoma cruzi recombinant antigens.
BACKGROUND
Blood transfusion is one of the most important transmission routes of Chagas' disease, a major parasitic infection in Latin America. Therefore, screening for antibodies to Trypanosoma cruzi is mandatory in blood banks in South America. Most of the commercial serologic tests employ epimastigote antigens and show a high number of inconclusive and false-positive results, with high economic and social costs.


METHODS
An ELISA using a mixture of three T. cruzi recombinant antigens, B13, 1F8, and H49 (mix-ELISA), was evaluated, first with a panel of well-characterized sera from 617 patients with Chagas' disease and 277 nonchagasic individuals, living in nine countries of South and Central America. Subsequently, the mix-ELISA was evaluated with 451 samples, from an endemic area of Brazil (Goiás), that were rejected from several blood banks because they presented discrepant results by two commercially available kits (indirect immunofluorescence assay, indirect hemagglutination assay, and/or ELISA).


RESULTS
The mix-ELISA exhibited 99.7 percent sensitivity and 98.6 percent specificity in the first evaluation with the 894 samples. In the second evaluation, 451 sera that had discrepant results in the first screening for Chagas' disease were further analyzed with the mix-ELISA. Upon consideration of the consensus results obtained with the trypomastigote excreted-secreted antigens blot test, a confirmatory test for Chagas' disease, the mix-ELISA led to a reduction in 99.6 percent in the number of discordant sera.


CONCLUSIONS
The combination of three T. cruzi recombinant antigens in a multiantigen immunoassay was highly sensitive and specific for Chagas' disease diagnosis. It is proposed that it can be applicable in blood bank screening in conjunction with the conventional serologic tests.
Umezawa
Eufrosina S
ES
Laboratory of Protozoology, Institute of Tropical Medicine of São Paulo, University of São Paulo, Brazil. eumezawa@usp.br
Bastos
Sueli F
SF
Coura
Jose R
JR
Levin
Mariano J
MJ
Gonzalez
Antonio
A
Rangel-Aldao
Rafael
R
Zingales
Bianca
B
Luquetti
Alejandro O
AO
da Silveira
Jose Franco
JF
D000818:Animals; D000953:Antigens, Protozoan / Q000276:immunology*; D014355:Chagas Disease / Q000175:diagnosis*; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D006801:Humans; D011994:Recombinant Proteins / Q000276:immunology; D012680:Sensitivity and Specificity; D012698:Serologic Tests; D014349:Trypanosoma cruzi / Q000276:immunology*
D000953:Antigens, Protozoan; D011994:Recombinant Proteins