Aislamiento de Rickettsia bellii a partir de Garrapatasamblyomma ovale y Amblyomma incisum procedentes del sur de Brasil / Isolation of Rickettsia bellii from Amblyomma ovale and Amblyomma incisum ticks from southern Brazil

ABSTRACT

Amblyomma incisum collected in the state of São Paulo. Materials and methods. Adult,free-living A. ovale and A. incisum were collected in an Atlantic rainforest area in the stateof São Paulo, Brazil. Each tick was tested using the hemolymph assay; samples from positiveticks were placed in shell vials in order to isolate rickettsiae and subsequently grown in Verocells. Amplification of three rickettsial genes (gltA, htrA and ompA) was attempted usingpolymerase chain reaction (PCR) for each isolate obtained. Amplicons were subsequentlysequenced. Results. A total of 388 A. incisum and 50 A. ovale were collected. Only one A.incisum and one A. ovale were hemolymph-test positive. Rickettsiae were successfullyisolated from these ticks; however establishment in Vero cell culture was successful only forthe isolate from A. ovale. Bacterial contamination in the first cell passage of the A. incisumisolate precluded successful isolation of the organism. PCR products were obtained with thegltA and htrA primers for the two isolates, but no product was obtained with the ompAprimers. By BLAST analysis, partial gltA and htrA sequences of isolates from A. ovale and A.incisum were similar to the corresponding sequences of R. bellii. Conclusions. This is thefirst report of R. bellii infecting A. incisum and the first successful isolation from A. ovale.