Molecular characterization of Ehrlichia canis from naturally infected dogs from the state of Rio de Janeiro
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The aim of the present study was to evaluate the genetic diversity of Ehrlichia canis in naturally infected dogs from six mesoregions of Rio de Janeiro state. E. canis was diagnosed with a real-time polymerase chain reaction (qPCR) targeting a 93 base pair (bp) fragment of the 16S rDNA gene. To evaluate the genetic diversity of the parasite, we amplified a positive sample from each mesoregion by distinct conventional PCR assays with targets in the gp19 (414 bp), gp36 (814 bp), and p28 (843 bp) genes. A total of 267 samples were collected from dogs in Rio de Janeiro state. Among the samples analyzed, 42.3% (n = 113/267) were 16S rDNA-qPCR positive. When performing PCR for the gp19 and gp36 genes, 100% (n = 113/113) and 5.3% (n = 6/113) of the samples amplified fragments of 414 bp and 814 bp, respectively. The six PCR-positive samples for the gp36 gene also amplified the p28 gene fragment. The characterization based on the gp19 gene demonstrated that it is highly conserved. In protein analysis (TRP36), all samples showed a tandem repeat protein (TRP) that comprised 11 replicates. Seven high-entropy amino acid sites were distributed throughout the gp36 gene. Eleven high-entropy amino acid sites were found throughout the p28 gene. There is a positive selection pressure in both genes (p ≤ 0.05). Comparing and characterizing an organism are useful for providing important information about the host’s immune response and identifying new antigenic targets, as well as essential characteristics for the development of vaccines and new diagnostic tools.
KeywordsGenetic diversity Molecular markers Epitopes Canine monocytic ehrlichiosis
This study was financially supported by the National Council for Scientific and Technological Development (CNPq) of Brazil, the “Carlos Chagas Filho” Foundation for Research Support of the state of Rio de Janeiro (FAPERJ) and Coordination of Improvement of Higher Education Personnel (CAPES) funds.
Compliance with ethical standards
Procedures performed on animals in this study were approved by the Ethics Committee on Animal Use of the UFRRJ (CEUA/UFRRJ) under procedure number 072/2014. These procedures comply with the basic and ethical principles for research involving the use of animals. All procedures were performed by a team of trained veterinarians.
Conflict of interest
The author(s) declared that there is no conflict of interest.
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