Open Access Research

New species of Ehrlichia isolated from Rhipicephalus (Boophilus) microplus shows an ortholog of the E. canis major immunogenic glycoprotein gp36 with a new sequence of tandem repeats

Alejandro Cabezas Cruz1, Erich Zweygarth2, Mucio Flavio Barbosa Ribeiro3, Julia Angelica Gonçalves da Silveira3, Jose de la Fuente45, Libor Grubhoffer1, James J Valdés1 and Lygia Maria Friche Passos26*

Author Affiliations

1 University of South Bohemia, Faculty of Science, České Budějovice, Czech Republic

2 Comparative Tropical Medicine and Parasitology, Ludwig-Maximilians-Universität München, Munich, Germany

3 Departamento de Parasitologia, ICB-UFMG, Belo Horizonte, Brazil

4 Instituto de Investigación de Recursos Cinegéticos, IREC, Ciudad Real, Spain

5 Department of Veterinary Pathobiology, Center for Veterinary Health Sciences, Oklahoma State University, Oklahoma, USA

6 Departamento de Medicina Veterinaria Preventiva, INCT-Pecuária, Escola de Veterinária-UFMG, Belo Horizonte, Minas Gerais, Brazil

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Parasites & Vectors 2012, 5:291  doi:10.1186/1756-3305-5-291

Published: 11 December 2012

Abstract

Background

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. The aim of this paper was to phylogeneticaly characterise a new species of Ehrlichia isolated from Rhipicephalus (Boophilus) microplus from Minas Gerais, Brazil.

Methods

The 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.

Results

The 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.

Conclusions

Based 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.

Keywords:
Ehrlichia spp; Rhipicephalus (Boophilus) microplus; Phylogenetic analysis; Gp36 major immunogenic protein