Evaluation of the ELISA-F29 test as an early marker of therapeutic efficacy in adults with chronic Chagas disease Avaliação do tratamento tripanossomicida em coorte de adultos chagásicos crônicos através de técnicas sorológicas convencionais e ELISA-F29

• Main Authors: Diana Fabbro, Elsa Velazquez, Maria Laura Bizai, Susana Denner, Verónica Olivera, Enrique Arias, Carlos Pravia, Andrés M. Ruiz
• Format: Article
• Language: English
• Published: Universidade de São Paulo 2013-06-01
• Series: Revista do Instituto de Medicina Tropical de São Paulo
• Subjects: Chagas disease; Trypanosoma cruzi; Chemotherapy; Diagnosis
• Online Access: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0036-46652013000300167

This work compared the time at which negative seroconversion was detected by conventional serology (CS) and by the ELISA-F29 test on a cohort of chronic chagasic patients treated with nifurtimox or benznidazole. A retrospective study was performed using preserved serum from 66 asymptomatic chagasic adults under clinical supervision, and bi-annual serological examinations over a mean follow-up of 23 years. Twenty nine patients received trypanocide treatment and 37 remained untreated. The ELISA-F29 test used a recombinant antigen which was obtained by expressing the Trypanosoma cruzi flagellar calcium-binding protein gene in Escherichia coli. Among the untreated patients, 36 maintained CS titers. One patient showed a doubtful serology in some check-ups. ELISA-F29 showed constant reactivity in 35 out of 37 patients and was negative for the patient with fluctuating CS. The treated patients were divided into three groups according to the CS titers: in 13 they became negative; in 12 they decreased and in four they remained unchanged. ELISA-F29 was negative for the first two groups. The time at which negativization was detected was significantly lower for the ELISA-F29 test than for CS, 14.5 &#177; 5.7 and 22 &#177; 4.9 years respectively. Negative seroconversion was observed in treated patients only. The results obtained confirm that the ELISA-F29 test is useful as an early indicator of negative seroconversion in treated chronic patients.<br>Este trabalho comparou os tempos de soroconvers&#227;o negativos obtidos pela sorologia convencional (CS) e teste ELISA-F29 em uma coorte de pacientes chag&#225;sicos cr&#244;nicos tratados com nifurtimox ou benznidazol. Um estudo retrospectivo foi realizado com soro preservado de 66 adultos chag&#225;sicos assintom&#225;ticos com acompanhamento cl&#237;nico e sorol&#243;gico semestral ao longo de um seguimento m&#233;dio de 23 anos. 29 pacientes receberam tratamento tripanossomicida e 37 outras permaneceram sem tratamento. O teste ELISA-F29 usou um ant&#237;geno recombinante obtido por express&#227;o do gene de uma prote&#237;na flagelar de Trypanosoma cruzi de liga&#231;&#227;o de c&#225;lcio em Escherichia coli. Entre os pacientes n&#227;o tratados, 36 mantiveram os t&#237;tulos da CS. Um paciente apresentou sorologia duvidosa em alguns controles. ELISA-F29 apresentou reatividade constante em 35/37 e foi negativo no paciente com CS flutuante. Os pacientes tratados foram agrupados de acordo com os t&#237;tulos da CS, em tr&#234;s grupos: 13 tornaram-se negativos, 12 diminu&#237;ram e quatro permaneceram inalterados. ELISA-F29 foi negativo nos dois primeiros grupos. O tempo de negativiza&#231;&#227;o foi significativamente menor para o teste ELISA-F29 do que para CS (14,5 &#177; 5,7 e 22 &#177; 4,9 anos, respectivamente). A soroconvers&#227;o negativa foi observada somente nos pacientes tratados. Os resultados obtidos confirmam que o teste ELISA-F29 &#233; &#250;til como um indicador precoce de soronegativa&#231;&#227;o em pacientes cr&#244;nicos tratados.