Rickettsia bellii and Rickettsia amblyommii in Amblyomma Ticks from the State of Rondônia, Western Amazon, Brazil

• Published in: Journal of medical entomology 2004-11, Vol.41 (6), p.1073-1081
• Main Authors: Labruna, Marcelo B., Whitworth, Ted, Bouyer, Donald H., McBride, Jere, Camargo, Luis Marcelo A., Camargo, Erney P., Popov, Vsevolod, Walker, David H.
• Format: Article
• Language: English
• Subjects: Amazon; Amblyomma; Animals; Base Sequence; Biological and medical sciences; Brazil; cell culture; Cercopithecus aethiops; detection; disease prevalence; disease vectors; DNA Primers; Fundamental and applied biological sciences. Psychology; Geography; Ixodidae - microbiology; Medically important nuisances and vectors, pests of stored products and materials: population survey and control; molecular sequence data; new host records; nucleotide sequences; pathogen identification; polymerase chain reaction; Rickettsia; Rickettsia - classification; Rickettsia - genetics; Rickettsia - isolation & purification; ticks; ultrastructure; VECTOR/PATHOGEN/HOST INTERACTION, TRANSMISSION; Vectors. Intermediate hosts; Vero Cells
• ISSN: 0022-2585; 1938-2928; 0022-2585
• DOI: 10.1603/0022-2585-41.6.1073

This study evaluates the rickettsial presence in Amblyomma ticks from eight areas of the Amazon forest in Rondônia, Brazil. The following tick species (number in parentheses) were examined: Amblyomma ovale Koch (121), Amblyomma cajennense (F.) (41), Amblyomma naponense (Packard) (36), Amblyomma scalpturatum Neumann (35), Amblyomma oblongoguttatum Koch (30), Amblyomma incisum Neumann (27), Amblyomma rotundatum Koch (16), Amblyomma coelebs Neumann (10), and Amblyomma humerale Koch (6). Ticks were examined individually or in pools (2–10 ticks) by polymerase chain reaction (PCR) targeting the gltA gene. The PCR-determined minimal infection rate for each tick species was A. ovale 28%, A. cajennense 27%, A. naponense 0%, A. scalpturatum 11%, A. oblongoguttatum 3%, A. incisum 0%, A. rotundatum 87%, A. coelebs 10%, and A. humerale 50%. Partial sequences of the gltA gene of Rickettsia from A. ovale, A. scalpturatum, A. oblongoguttatum, A. rotundatum, and A. humerale were 99.9% (349/350) identical to Rickettsia bellii. DNA sequences of PCR products from A. cajennense and A. coelebs were 100% (350/350) identical to Rickettsia amblyommii. R. bellii organisms were isolated in Vero cells from A. scalpturatum, A. ovale, A. rotundatum, and A. oblongoguttatum, but only one of the isolates, cultured from A. scalpturatum, was established in continuous cell culture passage. R. amblyommii was isolated from A. cajennense and was successfully established in continuous passage in cell culture. R. amblyommii infection of Vero cells was analyzed by transmission electron microscopy. This study adds South America to the known geographic distribution of R. amblyommii and reports rickettsiae in six Amblyomma species for the first time.