Amblyomma sculptum, Berlese, 1888

Amblyomma sculptum View in CoL ticks

Ticks used in the present study derived from a tick colony that was established in the laboratory from unfed adults collected from the environment by flannel cloth dragging and visual search [ 29] in the experimental farm of the School of Veterinary and Animal Science of the Federal University of Goiás (EVZ/UFG), namely A. sculptum strain GYN [ 30]. Tis experimental farm (16° 35 ′ 42 ″ S, 49° 16 ′ 50 ″ W) is located in the municipality of Goiânia, Goiás state, an area non-endemic for BSF. Te ticks were identified according to taxonomic key [ 31, 32]. To confirm that the colony was not naturally infected by SFG rickettsiae, rabbits and guinea pigs used for feeding ticks were tested for the presence of R. rickettsii -reactive antibodies before and 21 days after infestation with the ticks (serological protocol described below); none of the rabbits and guinea pigs seroconverted to R. rickettsii. Furthermore, molecular analysis (protocol describe below) failed to detect rickettsial DNA in tick samples (egg pools, nymphs and adults) during the establishment of the tick colony.

Te A. sculptum colony was used to form two separated cohorts in the laboratory, one uninfected (as it was originally) and one infected by R. rickettsii. For the latter, the larval and nymphal stages of a single generation were allowed to feed on rickettsemic guinea pigs that were intraperitoneally inoculated with a homogenate of R. rickettsii strain Itu-infected guinea pig organs, as previously described [ 11]. Molecular analysis showed the resultant adult ticks of this generation harbored a 30% infection rate by R. rickettsii, based on the testing of 20 unfed individual adults by PCR (protocol described below).