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1.
J Invertebr Pathol ; 90(3): 177-86, 2005 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-16288906

RESUMO

Rickettsia peacockii, a spotted fever group rickettsia, is a transovarially transmitted endosymbiont of Rocky Mountain wood ticks, Dermacentor andersoni. This rickettsia, formerly known as the East Side Agent and restricted to female ticks, was detected in a chronically infected embryonic cell line, DAE100, from D. andersoni. We examined infectivity, ability to induce cytopathic effect (CPE) and host cell specificity of R. peacockii using cultured arthropod and mammalian cells. Aposymbiotic DAE100 cells were obtained using oxytetracycline or incubation at 37 degrees C. Uninfected DAE100 sublines grew faster than the parent line, indicating R. peacockii regulation of host cell growth. Nevertheless, DAE100 cellular defenses exerted partial control over R. peacockii growth. Rickettsiae existed free in the cytosol of DAE100 cells or within autophagolysosomes. Exocytosed rickettsiae accumulated in the medium and were occasionally contained within host membranes. R. peacockii multiplied in other cell lines from the hard ticks D. andersoni, Dermacentor albipictus, Ixodes scapularis, and Ixodes ricinus; the soft tick Carios capensis; and the lepidopteran Trichoplusia ni. Lines from the tick Amblyomma americanum, the mosquito Aedes albopictus, and two mammalian cell lines were non-permissive to R. peacockii. High cell densities facilitated rickettsial spread within permissive cell cultures, and an inoculum of one infected to nine uninfected cells resulted in the greatest yield of infected tick cells. Cell-free R. peacockii also were infectious for tick cells and centrifugation onto cell layers enhanced infectivity approximately 100-fold. The ability of R. peacockii to cause mild CPE suggests that its pathogenicity is not completely muted. An analysis of R. peacockii-cell interactions in comparison to pathogenic rickettsiae will provide insights into host cell colonization mechanisms.


Assuntos
Dermacentor/parasitologia , Infecções por Rickettsia/microbiologia , Rickettsia/fisiologia , Animais , Dermacentor/crescimento & desenvolvimento , Dermacentor/ultraestrutura , Feminino , Interações Hospedeiro-Parasita , Microscopia Eletrônica de Transmissão , Rickettsia/patogenicidade , Infecções por Rickettsia/fisiopatologia , Simbiose
2.
Vet Microbiol ; 101(1): 53-64, 2004 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-15201033

RESUMO

Anaplasma marginale and A. phagocytophilum are obligate intracellular, tick-borne pathogens that target erythrocytes and neutrophil granulocytes, respectively. Because ticks do not directly tap blood vessels, an intermediate tissue may mediate infection of blood cells. We considered that vascular endothelium interacts with circulating blood cells in vivo, and could be involved in pathogenesis and dissemination of the organisms. We used light and electron microscopy and immune labeling to show that A. phagocytophilum invaded rhesus (RF/6A), human (HMEC-1, MVEC), as well as bovine (BCE C/D-1b) endothelial cell lines, whereas A. marginale infected rhesus and bovine endothelial cells. A. marginale formed large intracellular inclusions that appeared smooth and solid at first, and subsequently coalesced into discrete granules. A. phagocytophilum formed numerous smaller inclusions in each cell. Within 1-3 weeks, the monolayers were destroyed, and lysed cultures were diluted onto fresh monolayers. Electron microscopy demonstrated uneven distribution of A. marginale inside large inclusions, with reticulated forms grouped more tightly than denser cells, whereas in A. phagocytophilum individual organisms appeared more evenly spaced. Specific polyclonal and monoclonal antibodies both labeled A. marginale and A. phagocytophilum in endothelial cells, and oligonucleotide primers complimentary to either A. marginale or A. phagocytophilum amplified their expected target from these cultures. In conclusion, we demonstrate that relevant microvascular endothelium is susceptible to anaplasmas in vitro and may present a link that could explain development of the immune response and persistent infection.


Assuntos
Anaplasma marginale/patogenicidade , Anaplasma phagocytophilum/crescimento & desenvolvimento , Anaplasmose/microbiologia , Ehrlichiose/microbiologia , Células Endoteliais/microbiologia , Anaplasma marginale/genética , Anaplasma marginale/crescimento & desenvolvimento , Anaplasma marginale/imunologia , Anaplasma phagocytophilum/genética , Anaplasma phagocytophilum/imunologia , Anaplasmose/imunologia , Animais , Bovinos , DNA Bacteriano/química , DNA Bacteriano/genética , Ehrlichiose/imunologia , Eletroforese em Gel de Ágar , Células Endoteliais/imunologia , Células Endoteliais/ultraestrutura , Humanos , Macaca mulatta , Microscopia Eletrônica , Microscopia de Contraste de Fase , Reação em Cadeia da Polimerase , RNA Ribossômico 16S/química , RNA Ribossômico 16S/genética
3.
Appl Environ Microbiol ; 68(9): 4559-66, 2002 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-12200314

RESUMO

We describe the isolation and characterization of Rickettsia monacensis sp. nov. (type strain, IrR/Munich(T)) from an Ixodes ricinus tick collected in a city park, the English Garden in Munich, Germany. Rickettsiae were propagated in vitro with Ixodes scapularis cell line ISE6. BLAST analysis of the 16S rRNA, the citrate synthase, and the partial 190-kDa rickettsial outer membrane protein A (rOmpA) gene sequences demonstrated that the isolate was a spotted fever group (SFG) rickettsia closely related to several yet-to-be-cultivated rickettsiae associated with I. ricinus. Phylogenetic analysis of partial rompA sequences demonstrated that the isolate was genotypically different from other validated species of SFG rickettsiae. R. monacensis also replicated in cell lines derived from the ticks I. ricinus (IRE11) and Dermacentor andersoni (DAE100) and in the mammalian cell lines L-929 and Vero, causing cell lysis. Transmission electron microscopy of infected ISE6 and Vero cells showed rickettsiae within the cytoplasm, pseudopodia, nuclei, and vacuoles. Hamsters inoculated with R. monacensis had immunoglobulin G antibody titers as high as 1:16,384, as determined by indirect immunofluorescence assay. Western blot analyses demonstrated that the hamster sera cross-reacted with peptides from other phylogenetically distinct rickettsiae, including rOmpA. R. monacensis induced actin tails in both tick and mammalian cells similar to those reported for R. rickettsii. R. monacensis joins a growing list of SFG rickettsiae that colonize ticks but whose infectivity and pathogenicity for vertebrates are unknown.


Assuntos
Febre Botonosa/microbiologia , Rickettsia/isolamento & purificação , Carrapatos/microbiologia , Actinas/metabolismo , Animais , Anticorpos/imunologia , Febre Botonosa/epidemiologia , Cricetinae , DNA Bacteriano/análise , Feminino , Alemanha/epidemiologia , Masculino , Modelos Animais , Reação em Cadeia da Polimerase , Polimorfismo de Fragmento de Restrição , RNA Ribossômico 16S/análise , RNA Ribossômico 16S/genética , Rickettsia/classificação , Rickettsia/genética , Rickettsia/ultraestrutura
4.
J Med Entomol ; 39(3): 534-40, 2002 May.
Artigo em Inglês | MEDLINE | ID: mdl-12061452

RESUMO

We examined a parthenogenetic strain of the hard tick Ixodes woodi Bishopp for the presence of endosymbiotic bacteria. Electron microscopic examination revealed the ovarian tissues and Malpighian tubules were infected with pleomorphic bacteria. Two basic types were observed: a larger granular cell and a smaller condensed cell. Cloning and sequence analysis of polymerase chain reaction (PCR) amplified 16S rRNA gene yielded a single sequence from bacteria present in I. woodi tissues. Phylogenetic analysis of the nearly complete 16S rDNA indicated that the ticks were infected with an endosymbiont belonging to the gamma subdivision of the Proteobacteria. It clustered with the insect pathogenic species Rickettsiellagrylli (Vago and Martoja 1963) and the animal pathogen Coxiella burnetii (Derrick 1939) Philip 1948. Our results suggest that the I. woodi females harbored a single endosymbiotic bacterium related to selected Rickettsiella species and to C burnetii.


Assuntos
Ixodes/microbiologia , Rickettsieae/isolamento & purificação , Animais , Sequência de Bases , DNA Bacteriano/análise , DNA Ribossômico/análise , Ixodes/ultraestrutura , Camundongos , Dados de Sequência Molecular , Filogenia , RNA Ribossômico 16S/análise , Coelhos , Rickettsieae/classificação , Rickettsieae/genética , Rickettsieae/ultraestrutura , Simbiose
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