Análise clínico-patológica e soroepidemiológica pelo uso de 46 peptídeos sintéticos de proteínas TRP de Ehrlichia canis e Ehrlichia chaffeensis no Brasil

Abstract

Ehrlichias are Gram negative bacteria classified in the order Rickettsiales and family Anaplasmataceae. Among the six described species, we highlight Ehrlichia canis, which is the etiological agent of Canine Monocytic Ehrlichiosis (CME), a serious and endemic disease in Brazil, and E. chaffeensis, which is the etiological agent of Human Monocytic Ehrlichiosis (HME), an emerging zoonosis widespread in North America. From advances in the field of molecular biology, a group of proteins that have sequences of amino acid repetitions (tandem repeat protein-TRP) were identified and characterized. The TRP19 and TRP32 proteins were conserved among different isolates of E. canis and E. chaffeensis respectively. However, the TRP36 of E. canis showed divergence between isolates, making it an excellent target to identify different genotypes of the bacterium. These proteins are important and excellent for the diagnosis of ehrlichiosis. The present study aimed to evaluate the applicability of TRPs in the diagnosis of CME in a suspected canine population in an endemic area, to verify whether there are clinical and hematological differences in dogs infected by different genotypes, to determine the distribution of different E. canis genotypes in Brazil and to investigate dogs seroreactive to the E. chaffeensis antigen. TRP19 proved to be an excellent tool for the serological diagnosis of CME in an endemic area for canine ehrlichiosis. Clinical differences in dogs infected by distinct E. canis genotypes were not found. TRP19 showed a positive correlation with the protein variable and a negative correlation with hematocrit and platelets. USTRP36 showed a strong positive correlation with proteins. In addition, the diagnosis based on TRP19 showed an association with anemia, thrombocytopenia and hyperproteinemia. In general, the American and Brazilian E. canis genotypes are widely distributed in Brazil, except for the southern region of Brazil where the serum occurrence is low. Serological reaction to the TRP36 “Costa Rica” genotype and TRP32 protein was observed for the first time in Brazil.