Detection of Alpha and Gamma-Proteobacteria in Amblyomma triste (Acari: Ixodidae) from Uruguay

Abstract

Amblyomma triste is the most prevalent tick species reported in human tickbites in Uruguay and has been found to be infected with Rickettsia parkeri, but no othermicroorganisms have been reported from this tick. A sample of 254 adults of A. triste wascollected by Xagging on vegetation in suburban areas in southern Uruguay. Pools of Wveticks were assembled and a screening for the DNA from the resulting 51 pools was realizedby PCR assays using primers for amplifying a fragment of 16S rRNA gene for members ofAnaplasmataceae. Seventeen pools were positive (33%) and the sequenciation of the genefragment ampliWed revealed the presence of a putative new Alpha-Proteobacterium(denominated Atri-uru). The phylogenetic analysis showed that this microorganism isclosely related to the symbiont of I. ricinus denominated ‘Candidatus Midichloria mitochondrii’and other associated organisms. This rickettsial symbiont of ticks is included in arecent new clade proposed for the Alpha subclass of the Proteobacteria. The discovery ofthis bacterium in A. triste is the Wrst evidence of this group of Rickettsiales detected in theGenus Amblyomma, and the Wrst record in South America. Also, in two of 17 positivesamples a Gamma-Proteobacterium related to Francisella-like organisms was detected.