Abstract
BackgroundEhrlichia species are the etiological agents of emerging and life-threatening tick-borne human zoonoses that inflict serious and fatal infections in companion animals and livestock. The aim of this paper was to phylogeneticaly characterise a new species of Ehrlichia isolated from Rhipicephalus (Boophilus) microplus from Minas Gerais, Brazil.MethodsThe agent was isolated from the hemolymph of Rhipicephalus (B.) microplus engorged females that had been collected from naturally infested cattle in a farm in the state of Minas Gerais, Brazil. This agent was then established and cultured in IDE8 tick cells. The molecular and phylogenetic analysis was based on 16S rRNA, groEL, dsb, gltA and gp36 genes. We used the maximum likelihood method to construct the phylogenetic trees.ResultsThe phylogenetic trees based on 16S rRNA, groEL, dsb and gltA showed that the Ehrlichia spp isolated in this study falls in a clade separated from any previously reported Ehrlichia spp. The molecular analysis of the ortholog of gp36, the major immunoreactive glycoproteins in E. canis and ortholog of the E. chaffeensis gp47, showed a unique tandem repeat of 9 amino acids (VPAASGDAQ) when compared with those reported for E. canis, E. chaffeensis and the related mucin-like protein in E. ruminantium.ConclusionsBased on the molecular and phylogenetic analysis of the 16S rRNA, groEL, dsb and gltA genes we concluded that this tick-derived microorganism isolated in Brazil is a new species, named E. mineirensis (UFMG-EV), with predicted novel antigenic properties in the gp36 ortholog glycoprotein. Further studies on this new Ehrlichia spp should address questions about its transmissibility by ticks and its pathogenicity for mammalian hosts.
Highlights
Ehrlichia species are the etiological agents of emerging and life-threatening tick-borne human zoonoses that inflict serious and fatal infections in companion animals and livestock
In the present study we report further molecular and phylogenetic analyses focusing on five genes (16S rRNA, groESL, gltA, dsb and gp36) of this new organism, on referred as Ehrlichia mineirensis (UFMG-EV)
Our analysis of a relevant fragment of 16S rRNA sequences revealed that the novel agent found in Brazilian R. (B.) microplus ticks was closely related to E. canis [GenBank: GU810149], but was closely related to E. chaffeensis [GenBank: AF147752] showing 98.3% and 96.9% of homology, respectively
Summary
Ehrlichia species are the etiological agents of emerging and life-threatening tick-borne human zoonoses that inflict serious and fatal infections in companion animals and livestock. Ehrlichiae are tick-transmitted obligate intracellular gram-negative bacteria that are maintained in nature by persistent infection of mammalian hosts [1]. They are microorganisms residing within the cytoplasmic vacuoles of monocytes, granulocytes, or platelets of humans and animals. The obligately intracellular alpha-proteobacterial genus Ehrlichia (Rickettsiales: Anaplasmataceae) is spread all over the world and are comprised of five recognized species that are tick-transmitted, with three of the five causing human ehrlichiosis (E. canis, E. chaffeensis, and E. ewingii) [3]. Only three species of the genus Ehrlichia have been reported in Brazil: E. canis, E. ewingii and E. chaffeensis [5]
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