Novel Ehrlichia sp. detected in Magellanic penguins (Sphenicus magellanicus) and in the seabird tick Ixodes uriae from Magdalena Island, southern Chile

摘要

Ehrlichia spp. are obligatory intracellular microorganisms that infect hematopoietic, endothelial or blood cells of mammals. Ticks are the only vectors of these agents in nature. To date, the role of birds and their associated ticks as reservoirs of ehrlichiae remains almost unexplored. In this study, we performed a molecular screening for bacteria of Anaplasmataceae family in samples of spleen (n = 72) and lung (n = 17), recovered from 72 carcasses of Magellanic penguins (Spheniscus magellanicus) in Brazil and Chile. One apparently unengorged tick (Ixodes uriae) was also collected while wandering upon one of the carcasses and submitted to molecular analyses as well. Through conventional and nested PCR protocols three genes (16S rRNA, dsb and groEL) of a new Ehrlichia sp. were partially characterized upon organs of three penguins and in the tick coming from Magdalena Island (Chile). First matches after BLASTn comparisons showed that our sequences share 99.4% (16S rRNA), 94.6% (groEL) and 79.3% (dsb) of identity with "Candidatus Ehrlichia ornithorhynchi", Ehrlichia sp. NS101 and Ehrlichia canis CCZ, respectively. Matrixes of genetic distance including other representatives of the Ehrlichia genus point a 99.4%, 94.0%, and 80.0% of identity with 16S rRNA, groEL and dsb genes from Ehrlichia sp. It25, Ehrlichia sp. NS101, and Ehrlichia chaffeensis San Louis, respectively. A Bayesian phylogenetic analysis of Anaplasmataceae 16S rRNA gene places the detected Ehrlichia sp. into a group with Ehrlichia sp. BAT and Ehrlichia sp. Natal. Although depicting different topologies, Bayesian unrooted phylogenetic trees constructed for groEL and dsb genes position this Ehrlichia sp. into well-supported branches, which reinforces the finding of a new taxon. For the moment, any pathogenic effect of this new Ehrlichia sp. on penguins is still unknown. However, this fact becomes important to assess from a conservation point of view since populations of Magellanic penguins are currently threatened and in an ongoing decrease.