Development of Babesia gibsoni in the midgut of the nymphal stage of the tick, Rhipicephalus sanguineus.
(17/948)
Studies were made on the development of Babesia gibsoni in the midgut of the nymphal stage of the tick, Rhipicephalus sanguineus. Six hr after repletion, merozoites of B. gibsoni, free of erythrocytes, were observed in the midgut contents of the ticks. After that, within 24 hr, those merozoites were transformed into ring-forms which were relatively large ring 1-2 microns in diameter. Later, the ring forms developed into spherical forms which were somewhat elliptical in shape and 3-4 microns in diameter. Within 2-4 days, bizarre forms (5-6 microns in diameter) developed into elongated forms (5-6 microns in length). About 5-6 days after repletion, large round or elliptic zygotes (7-9 microns in diameter) were observed in the ticks gut. (+info)
The incidence of ehrlichial and rickettsial infection in patients with unexplained fever and recent history of tick bite in central North Carolina.
(18/948)
We examined the clinical and laboratory findings of a consecutive series of patients from central North Carolina presenting with fever and a history of tick bite within the preceding 14 days. Evidence of a tick-transmitted pathogen was detected in 16 of 35 patients enrolled over a 2-year period. Nine patients were infected with Ehrlichia chaffeensis, and 6 were infected with a spotted fever group rickettsia; 1 patient had evidence of coinfection with E. chaffeensis and a spotted fever group rickettsia. Four patients had detectable antibodies against the human granulocytic ehrlichiosis agent; however, only 2 had a 4-fold antibody titer rise without detectable antibodies against E. chaffeensis. The other 2 were thought to have cross-reacting antibodies to E. chaffeensis. We conclude that ehrlichial infections may be as common as spotted fever group rickettsial infections in febrile patients from central North Carolina with a recent history of tick bite. (+info)
Theileria sp. Infections associated with bovine fatalities in the United States confirmed by small-subunit rRNA gene analyses of blood and tick samples.
(19/948)
Theileria sp.-specific small subunit (SSU) rRNA gene amplification confirmed the presence of the organism in cattle and in Amblyomma americanum and Dermacentor variabilis ticks collected from a cattle herd in Missouri. Blood from the index animal had type A and type D Theileria SSU rRNA genes. The type D gene was also found in blood from two cohort cattle and tick tissues. The type A SSU rRNA gene was previously reported from bovine Theileria isolates from Texas and North Carolina; the type D gene was reported from a Texas cow with theileriosis. (+info)
Antimicrobial activity of a bovine hemoglobin fragment in the tick Boophilus microplus.
(20/948)
Antifungal and antibacterial activities were detected in the hemolymph and gut contents of the cattle tick, Boophilus microplus. A peptide with antibacterial activity from the tick gut contents was purified to homogeneity by reversed-phase chromatography. The molecular mass of the purified peptide was 3,205.7 Da, measured by matrix-assisted laser desorption/ionization mass spectrometry. The amino acid sequence was obtained by Edman degradation and showed that the peptide was identical to a fragment of the bovine alpha-hemoglobin. A synthetic peptide based on the sequence obtained showed characterization data identical to those of the isolated material, confirming its structure. The synthetic peptide was active in micromolar concentrations against Gram-positive bacteria and fungi. These data led us to conclude that the antibacterial activity detected in tick gut contents is the result of enzymatic processing of a host protein, hemoglobin. This activity may be used by ticks as a defense against microorganisms. (+info)
African swine fever virus replication in the midgut epithelium is required for infection of Ornithodoros ticks.
(21/948)
Although the Malawi Lil20/1 (MAL) strain of African swine fever virus (ASFV) was isolated from Ornithodoros sp. ticks, our attempts to experimentally infect ticks by feeding them this strain failed. Ten different collections of Ornithodorus porcinus porcinus ticks and one collection of O. porcinus domesticus ticks were orally exposed to a high titer of MAL. At 3 weeks postinoculation (p.i.), <25% of the ticks contained detectable virus, with viral titers of <4 log(10) 50% hemadsorbing doses/ml. Viral titers declined to undetectability in >90% of the ticks by 5 weeks p.i. To further study the growth defect, O. porcinus porcinus ticks were orally exposed to MAL and assayed at regular intervals p.i. Whole-tick viral titers dramatically declined (>1,000-fold) between 2 and 6 days p.i., and by 18 days p.i., viral titers were below the detection limit. In contrast, viral titers of ticks orally exposed to a tick-competent ASFV isolate, Pretoriuskop/96/4/1 (Pr4), increased 10-fold by 10 days p.i. and 50-fold by 14 days p.i. Early viral gene expression, but not extensive late gene expression or viral DNA synthesis, was detected in the midguts of ticks orally exposed to MAL. Ultrastructural analysis demonstrated that progeny virus was rarely present in ticks orally exposed to MAL and, when present, was associated with extensive cytopathology of phagocytic midgut epithelial cells. To determine if viral replication was restricted only in the midgut epithelium, parenteral inoculations into the hemocoel were performed. With inoculation by this route, a persistent infection was established although a delay in generalization of MAL was detected and viral titers in most tissues were typically 10- to 1,000-fold lower than those of ticks injected with Pr4. MAL was detected in both the salivary secretion and coxal fluid following feeding but less frequently and at a lower titer compared to Pr4. Transovarial transmission of MAL was not detected after two gonotrophic cycles. Ultrastructural analysis demonstrated that, when injected, MAL replicated in a number of cell types but failed to replicate in midgut epithelial cells. In contrast, ticks injected with Pr4 had replicating virus in midgut epithelial cells. Together, these results indicate that MAL replication is restricted in midgut epithelial cells. This finding demonstrates the importance of viral replication in the midgut for successful ASFV infection of the arthropod host. (+info)
Conformational nature of the Borrelia burgdorferi B31 outer surface protein C protective epitope.
(22/948)
Active immunization with Escherichia coli-expressed recombinant outer surface protein C (OspC) of Borrelia burgdorferi has been demonstrated to confer protection against a tick-transmitted infection on laboratory animals. A previous study in this laboratory showed that OspC antibody raised against a denatured immunogen isolated from B. burgdorferi cells failed to provide protective immunity. Therefore, to determine whether the protective epitope of the recombinant antigen was sensitive to denaturation, recombinant OspC preparations were subjected to heat and chemical treatments prior to animal immunization. Following seroconversion to OspC, the animals were challenged with an infectious dose of B. burgdorferi B31 by tick bite. Whereas mice immunized with a soluble, nondenatured form continued to show protection rates close to 100%, mice that had been immunized with denatured antigen were not protected. Furthermore, mice that were immunized with an insoluble (rather than a soluble), nondenatured form of the recombinant OspC showed a protection rate of only 40%. Protective epitope localization experiments showed that either the amino or the carboxy end of the recombinant protein was required to react with a protective OspC-specific monoclonal antibody. The data from these experiments demonstrate that a conformational organization of the protein is essential for the protective capability of the strain B31 OspC immunogen. (+info)
An OspC-specific monoclonal antibody passively protects mice from tick-transmitted infection by Borrelia burgdorferi B31.
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A murine monoclonal antibody directed against Borrelia burgdorferi B31 outer surface protein C (OspC) antigen was generated by a method whereby borreliae were inoculated into the mouse via the natural transmission mode of tick feeding. Passive immunization with this antibody resulted in protection of C3H/HeJ and outbred mice from a tick-transmitted challenge infection. Immunofluorescence staining of borrelia cells indicated surface exposure of the OspC epitope reactive with the monoclonal antibody. (+info)
Population dynamics of a naturally occurring heterogeneous mixture of Borrelia burgdorferi clones.
(24/948)
Two unique isolates of Borrelia burgdorferi, differing in plasmid content and outer surface protein C expression, were cultured on sequential captures of a single free-living Peromyscus leucopus mouse and were examined for differences in transmissibility. Both isolates were transmissible from inoculated C.B-17 mice to larval Ixodes scapularis ticks and, subsequently, from infected nymphal ticks to C3H/HeJ mice. Plasmid and protein analyses suggested that the original isolates were a mixed population of B. burgdorferi, and cloning by limiting dilution resulted in the identification of two clonal groups. In addition to being heterogeneous in plasmid and genomic macrorestriction analyses, the clones varied with respect to the electrophoretic mobilities and antigenicity of their OspC proteins, as shown by their reactivity to a panel of monoclonal antibodies. Plasmid analysis of sequential isolates from C3H mice experimentally infected with the primary isolate or various mixtures of its subclones showed an apparently random fluctuation in clonal dominance in the majority of mice. Surprisingly, mice infected with each subclone were permissive to superinfection with the heterologous subclone, despite the presence of anti-B. burgdorferi antibodies at the time of the secondary challenge. These results show conclusively that mice captured at Lyme disease enzootic sites may be infected by mixed populations of genetically and antigenically distinct B. burgdorferi clones and that these infections can be acquired by coinfection or by sequential infection. The lack of cross-immunization between clones existing within a naturally occurring population may play a role in the maintenance of the genetic heterogeneity of B. burgdorferi in nature. (+info)