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Natural Infection, Transovarial Transmission, and Transstadial Survival of Rickettsia bellii in the Tick Ixodes loricatus (Acari: Ixodidae) from Brazil
Author(s) -
HORTA MAURICIO C.,
PINTER ADRIANO,
SCHUMAKER TERESINHA T. S.,
LABRUNA MARCELO B.
Publication year - 2006
Publication title -
annals of the new york academy of sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.712
H-Index - 248
eISSN - 1749-6632
pISSN - 0077-8923
DOI - 10.1196/annals.1374.053
Subject(s) - ixodidae , acari , biology , transovarial transmission , tick , virology , transmission (telecommunications) , argasidae , tick borne disease , larva , zoology , ecology , electrical engineering , engineering
An Ixodes loricatus engorged female, infected with Rickettsia bellii , was collected from an opossum ( Didelphis aurita ) in Mogi das Cruzes, São Paulo State, Brazil. Two consecutive laboratory tick generations (F 1 and F 2 ) reared from this single engorged female were evaluated for Rickettsia infection by polymerase chain reaction (PCR) targeting specific Rickettsia genes. Immature ticks fed on naïve Wistar rats ( Rattus norvegicus ) and adult ticks fed on opossum ( D. aurita ), both free of ticks and rickettsial infection. PCR performed on individual ticks from the F 1 (20 larvae, 10 nymphs, and 10 adults) and the F 2 (30 larvae, 30 nymphs, and 15 adults) yielded expected bands compatible with Rickettsia. All the PCR products that were sequenced, targeting gltA gene, resulted in sequences identical to each other and 99.7% (349/350) similar to the corresponding sequence of R. bellii in GenBank. The R. bellii infection on ticks from the second laboratory generation (F 2 ) was confirmed by other PCR protocols and successful isolation of R. bellii in cell culture. We report for the first time a Rickettsia species infecting I. loricatus , and the first report of R. bellii in the tick genus Ixodes. We conclude that there was an efficient transovarial transmission and transstadial survival of this Rickettsia species in the tick I. loricatus. Our results suggest that R. bellii might be maintained in nature solely by transovarial transmission and transstadial survival in ticks (no amplifier vertebrate host is needed), since there has been no direct or indirect evidence of infection of vertebrate hosts by R. bellii .