Two novel Ehrlichia(Rickettsiales: Anaplasmataceae) strains detected in ticks (Ixodida, Ixodidae) and opossums (Didelphimorphia: Didelphidae) in Argentina

The aim of this study is to determine if there is circulation of microorganisms of the genus Ehrlichiain opossums Didelphis albiventrisand their ticks from the Humid Chaco in Argentina. Blood samples of 15 specimens of the opossum D. albiventriswere analysed. Immature stages of the ticks Amblyomma ovale(Larvae=26; Nymphs=10), Amblyomma sculptum(Larvae=86; Nymphs=6) and Ornithodorossp. cf. O. mimon(Larvae=90) were also analyzed. DNA was extracted individually from blood samples and ticks. Molecular detection of Ehrlichiaagents was performed targeting two different loci: 16S rRNA and dsb gen. The phylogenetic analyses showed that the Ehrlichiasp. detected in D. albiventrisin this study is identical to Ehrlichiasp. strain Natal previously detected in two marsupials from Brazil. Furthermore, a new Ehrlichia strain was amplified from an A. ovalenymph (named as Ehrlichiasp. strain El Bagual) which is phylogenetically closely related to a strain of Ehrlichiasp. detected in Bradypus tridactylusin Brazil. The findings of the current study represent the first report of these two strains of Ehrlichiafor Argentina, showing that the diversity of Ehrlichiaspp. is greater than previously assumed. Further studies should determine the epidemiological relevance of these findings.