Ticks and Tick-borne Diseases 3 (2012) 203–206 Contents lists available at SciVerse ScienceDirect Ticks and Tick-borne Diseases journa l h o mepage: www.elsevier.de/ttbdis Original article Coxiella symbiont in the tick Ornithodoros rostratus (Acari: Argasidae) Aliny P. Almeida a , Arlei Marcili a , Romario C. Leite b , Fernanda A. Nieri-Bastos a , Luísa N. Domingues b , João Ricardo Martins c , Marcelo B. Labruna a,∗ a Dept. of Preventive Veterinary Medicine and Animal Health, Faculty of Veterinary Medicine, University of São Paulo, São Paulo, SP, Brazil b Dept. of Preventive Veterinary Medicine, School of Veterinary, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil c Institute of Veterinary Research “Desidério Finamor”, Fundac ¸ ão Estadual de Pesquisa Agropecuária, Eldorado do Sul, RS, Brazil a r t i c l e i n f o Article history: Received 30 November 2011 Received in revised form 10 February 2012 Accepted 24 February 2012 Keywords: Soft ticks Coxiella Ornithodoros rostratus Symbiont Brazil a b s t r a c t In the present study, the presence of tick-associated bacteria and protozoa in Ornithodoros rostratus ticks (adults, nymphs, and eggs) from the Pantanal region of Brazil were determined by molecular detection. In these ticks, DNA from protozoa in the genera Babesia and Hepatozoon, and bacteria from the genera Rickettsia, Borrelia, Anaplasma, and Ehrlichia were not detected. Conversely, all tested ticks (100%) yielded PCR products for 3 Coxiella genes (16S rRNA, pyrG, cap). PCR and phylogenetic analysis of 3 amplified genes (16S rRNA, pyrG, cap) demonstrated that the agent infecting O. rostratus ticks was a member of the genus Coxiella. This organism grouped with Coxiella symbionts of other soft tick species (Argasidae), having different isolates of C. burnetii as a sister group, and these 2 groups formed a clade that grouped with another clade containing Coxiella symbionts of hard tick species (Ixodidae). Analysis of tick mitochondrial 16S rRNA gene database composed mostly of tick species previously shown to harbor Coxiella symbionts suggests a phylogenetic congruence of ticks and their Coxiella symbionts. Furthermore, these results suggest a very long period of coevolution between ticks and Coxiella symbionts and indicates that the original infection may have occurred in an ancestor common to the 2 main tick families, Argasidae (soft ticks) and Ixodidae (hard ticks). However, this evolutionary relationship must be confirmed by more extensive testing of additional tick species and expanded populations. © 2012 Elsevier GmbH. All rights reserved. Introduction The Gammaproteobacterium Coxiella burnetii is the causative agent of acute Q fever and chronic endocarditis in humans world- wide, including Brazil (Siciliano et al., 2008; Lemos et al., 2011), where the agent is transmitted mostly by aerosol route or ingestion of infected animal fomites (Maurin and Raoult, 1999). C. burnetii is an obligately intracellular, Gram-negative bacterium that often resides in the phagolysosome of infected mammalian cells. Besides C. burnetii, a number of different tick species of both Argasidae (soft ticks) and Ixodidae (hard ticks) families have been reported to har- bor microbes related to C. burnetii (Mediannikov et al., 2003; Reeves et al., 2006; Klyachko et al., 2007; Machado-Ferreira et al., 2011). Although more than 40 tick species can be infected with C. burnetii, direct transmission of this agent to humans from infected ticks has never been documented. Ticks may play a significant role in the transmission of C. burnetii among wild vertebrates (Maurin and Raoult, 1999; Kazar, 2005); however, except for C. burnetii, there is ∗ Corresponding author at: Faculdade de Medicina Veterinária e Zootecnia, Uni- versidade de São Paulo, Av. Prof. Orlando Marques de Paiva 87, Cidade Universitária, São Paulo 05508-270, SP, Brazil. Tel.: +55 11 3091 1394; fax: +55 11 3091 7928. E-mail address: labruna@usp.br (M.B. Labruna). no evidence that demonstrates that such Coxiella-related organisms cause disease in humans or other vertebrate hosts. Hence, these Coxiella-related organisms are thought to be highly prevalent tick endosymbionts that are maintained transovarially (Klyachko et al., 2007; Machado-Ferreira et al., 2011). The soft tick Ornithodoros rostratus (Acari: Argasidae) is known to occur in northern Argentina, Paraguay, Bolivia, and western Brazil (Aragão, 1936; Nava et al., 2007). In Brazil, O. rostratus was recently reported in a Pantanal area of the state of Mato Grosso do Sul, where it was associated with several domestic animals (cattle, horses, pigs), and was also reported to be an important human bit- ing tick (Aragão, 1936; Canc ¸ ado et al., 2008). Within this context, the present study searched by molecular methods for the presence of tick-associated bacteria and protozoa in O. rostratus ticks from the Pantanal region of Brazil. Materials and methods In March 2009, Ornithodoros ticks were collected from the envi- ronment at the Nhumirim farm, in the central area of the Brazilian Pantanal, state of Mato Groso do Sul (18 ◦ 59 ′ S; 56 ◦ 39 ′ W). Ticks were collected by CO 2 traps armed on the sandy soil inside a cat- tle ranch, as previously described (Canc ¸ ado et al., 2008). Ecological 1877-959X/$ – see front matter © 2012 Elsevier GmbH. All rights reserved. doi:10.1016/j.ttbdis.2012.02.003