Molecular detection of Rickettsia bellii and Rickettsia sp. strain Colombianensi in ticks from Cordoba, Colombia

Abstract

The purpose of this study was to provide molecular evidence of Rickettsia spp. in ticks collected from 2 sites of Cordoba. From May to June 2009, 1069 Amblyomma cajennense ticks were removed from 40 capybaras (Hydrochoerus hydrochaeris) in a rural locality of Monteria. Furthermore, 458 Amblyomma sp. larvae and 20 Amblyomma sp. nymphs were collected in a rural locality of Los Cordobas (Cordoba) by drag sampling on vegetation (n=1547). Ticks were grouped into pools and tested for rickettsial infection by real-time PCR targeting the rickettsial gene gltA. Subsequently, PCR targeting for gltA, ompA, ompB, and 16S rRNA, sequencing, and phylogenetic analyses were undertaken. Rickettsial DNA was detected in 10 (4.6%) out of 214 pools of ticks by RT-PCR. Five (33%) of free-living Amblyomma sp. larval pools were positive, as well as 5 (2.6%) pools from A. cajennense. Only the gltA gene was amplified from 5 pools of free-living larvae. The nucleotide sequences were 100% identical to R. bellii by BLAST. Only one pool from A. cajennense was positive for gltA, ompA, ompB, and 16S rRNA. The partial nucleotide sequences of these genes were 100% identical to nucleotide sequences of the same genes of a new proposed species Candidatus Rickettsia sp. strain Colombianensi. This is the first report of R. bellii in ticks in Colombia and the second report of detection of Candidatus Rickettsia sp. strain Colombianensi. These Rickettsia species are still considered of unknown pathogenicity. Further studies are needed to characterize the ecological and potential pathogenic role of these 2 Rickettsia species found in Cordoba.