INVESTIGADORES
NAVA Santiago
artículos
Título:
Infection by Rickettsia bellii and Candidatus Rickettsia amblyommii in Amblyomma neumanni ticks from Argentina.
Autor/es:
MARCELO B. LABRUNA, RICHARD C. PACHECO, SANTIAGO NAVA, PAULO E. BRANDAO, LEONARDO J. RICHZENHAIN, ALBERTO A. GUGLIELMONE.
Revista:
MICROBIAL ECOLOGY
Referencias:
Año: 2007 vol. 54 p. 126 - 133
ISSN:
0095-3628
Resumen:
Rickettsia parkeri in Argentina
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The tick species, Amblyomma
neumanni (Acari: Ixodidae) is the most frequent tick parasitizing humans in
northwestern Argentina.
The present study evaluated the rickettsial infection among 55 A. neumanni adult free-living ticks collected
in Dean Funes, Córdoba Province. Ticks were individually
processed by the hemolymph test with Gimenez staining, isolation of rickettsia
in Vero cell culture by the shell vial technique, and polymerase chain reaction
(PCR) targeting the citrate synthase rickettsial gene. Through the shell vial technique, rickettsiae was successfully isolated and
established in Vero cell culture from two ticks (ticks #4 and #13), which
previously showed to contain Rickettsia-like
organisms by the hemolymph test. These two Rickettsia
isolates were designated as An4 and An13. Molecular characterization
(partial DNA sequences of two to three rickettial genes were determined) of
these two isolates and phylogenetic analyses identified them as Rickettsia bellii (isolate An4) and Candidatus Rickettsia amblyommii (isolate An13). After testing all A. neumanni ticks by PCR, the prevalence
of Candidatus R. amblyommii and R. bellii was 23.6% (13/55) and 3.6%
(2/55), respectively. These two rickettsiae have been considered of unknown
pathogenicity and appropriate studies to test their pathogenicity to humans or
animals need to be conducted. This is the first report of Rickettsia in ticks from Argentina, and also in the species A. neumanni. The results reinforce
previous findings that R. bellii (and
probably Candidatus R. amblyommii)
are widespread among some Neotropical Amblyomma
species, suggesting that these ticks gained these bacterial agents from a
common ancestor and/or by recent horizontal transmission of rickettsiae between
ticks.