Molecular diagnostics of Ehrlichia canis in dogs from Goiânia state of Goiás, Brazil

Abstract

The obligate intracellular bacterial parasite known as Ehlichia canis is the etiological agent of the Canine Monocytic Erhlichiosis. The most frequent applied method for routine laboratory diagnosis is based on the microscopic direct detection of intraleucocytic inclusions. More recently the polymerase chain reaction (PCR) has been introduced to improve mainly the sensitivity and specificity of diagnosis. The objective of this study was to investigate the presence of Ehrlichia in dogs from the city of Goiânia, Goiás by molecular techniques. Blood samples were collected from 40 symptomatic dogs referred to the Veterinary Hospital of the Federal University of Goiás. All samples were processed for DNA extraction and PCR using both genus and species-specific oligonucleotides for the 16S rRNA gene. PCR reactions resulted positive for both genus and species assays for 17 out of 40 tested samples. The species-specific PCR products of the 17 samples were purified and sequenced but only five of these were considered for subsequently molecular studies due to the quality analysis results of the sequences. These five sequences were then analyzed for similarity by BLASTn algorithm in which they could be identified as Ehrlichia canis. Using Mega4 software it was confirmed that these isolates of E. canis from dogs of Goiânia are highly similar to other reference isolates of the same species from other regions of Brazil and worldwide. The isolates of E. canis evaluated in this study are phylogenetically similar to those reference isolates from other geographic regions of the world. Sequencies were deposited in the GenBank as E. canis 16S rRNA parcial sequencies from Goiânia.