Publications

TitleAbstractYear
Filter
PMID(sorted descending)
Filter
detection and identification of ehrlichia, borrelia burgdorferi sensu lato, and bartonella species in dutch ixodes ricinus ticks.a sensitive and specific pcr hybridization assay was developed for the simultaneous detection and identification of ehrlichia and borrelia burgdorferi sensu lato. in separate assays the 16s rrna gene of ehrlichia species and the 23s-5s rrna spacer region of b. burgdorferi sensu lato were amplified and labeled by pcr. these pcr products were used in a reverse line blot hybridization assay in which oligonucleotide probes are covalently linked to a membrane in parallel lines. hybridization of the s ...199910364588
successive tick infestations selectively promote a t-helper 2 cytokine profile in mice.several studies have revealed that t lymphocytes and cytokines play a crucial role in determining the outcome of parasitic infections in terms of protective immunity. in this study we found that rhipicephalus sanguineus tick saliva stimulates transforming growth factor-beta (tgf-beta), and reduces interleukin-12 (il-12) secretion by cells from normal c3h/hej mice. moreover, murine lymph node cells harvested 6 days after the fourth infestation with ticks presented an 82.4% decrease in their proli ...199910233725
restriction of major surface protein 2 (msp2) variants during tick transmission of the ehrlichia anaplasma marginale.anaplasma marginale is an ehrlichial pathogen of cattle that establishes lifelong persistent infection. persistence is characterized by rickettsemic cycles in which new a. marginale variant types, defined by the sequence of the expressed msp2 transcripts, emerge. the polymorphic msp2 transcripts encode structurally distinct msp2 proteins and result in an antigenically diverse and continually changing a. marginale population within the blood. in this manuscript, we used sequence analysis of msp2 ...199910077656
comparison of ehrlichia muris strains isolated from wild mice and ticks and serologic survey of humans and animals with e. muris as antigen.in metropolitan tokyo, the ehrlichia muris seropositivity rate of 24 wild mice was 63% in hinohara village, but in the surrounding areas, it was 0 to 5%. this finding suggests that the reservoir of e. muris is focal. among the 15 seropositive mice, ehrlichiae were isolated from 9 apodemus speciosus mice and 1 a. argenteus mouse, respectively. five ehrlichial isolates were obtained from 10 ticks (haemaphysalis flava) collected in asuke town, aichi prefecture, where the e. muris type strain had be ...199910074536
body lice as tools for diagnosis and surveillance of reemerging diseases.body lice are vectors of three bacteria which cause human disease: rickettsia prowazekii, the agent of epidemic typhus; bartonella quintana, the agent of trench fever; and borrelia recurrentis, the agent of relapsing fever. a recrudescence of body lice is being observed as the numbers of individuals living under social conditions which predispose individuals to infestation have increased. because this phenomenon may lead to the reemergence of infections transmitted by body lice, we aimed to asse ...19999986818
lethal effect of rickettsia rickettsii on its tick vector (dermacentor andersoni).rickettsia rickettsii, the causative agent of rocky mountain spotted fever, was lethal for the majority of experimentally and transovarially infected rocky mountain wood ticks (dermacentor andersoni). overall, 94.1% of nymphs infected as larvae by feeding on rickettsemic guinea pigs died during the molt into adults and 88. 3% of adult female ticks infected as nymphs died prior to feeding. in contrast, only 2.8% of uninfected larvae failed to develop into adults over two generations. infected fem ...19999925615
comparison of surface proteins of anaplasma marginale grown in tick cell culture, tick salivary glands, and cattle.anaplasma marginale, a tick-borne rickettsial pathogen of cattle, infects bovine erythrocytes, resulting in mild to severe hemolytic disease that causes economic losses in domestic livestock worldwide. recently, the virginia isolate of a. marginale was propagated in a continuous tick cell line, ide8, derived from embryonic ixodes scapularis. development of a. marginale in cell culture was morphologically similar to that described previously in ticks. in order to evaluate the potential of the cel ...19999864202
persistence of anaplasma ovis infection and conservation of the msp-2 and msp-3 multigene families within the genus anaplasma.goats which have recovered from acute anaplasma ovis infection remain seropositive, although infected erythrocytes cannot be detected by microscopic examination. persistence of a. ovis 17 to 21 months following experimental infection was demonstrated by pcr detection of the msp-5 gene. quantitative analysis of persistent rickettsemia over time showed that all levels were below the limit of microscopic detection and ranged from a low of 10(2) organisms/ml to peaks of 10(6) organisms/ml. two patte ...19989826393
tick-borne relapsing fever in british columbia, canada: first isolation of borrelia hermsii.the spirochete that causes tick-borne relapsing fever, borrelia hermsii, was isolated in pure culture during 1995 and 1996 from three acutely ill human patients infected in southern british columbia, canada. the geographic area of exposure is a known focus of this disease dating back to 1930 when the first case was recognized in a human. analyses of plasmid dna, protein profiles, and reactivity with a species-specific monoclonal antibody identified the new isolates of spirochetes as b. hermsii, ...19989817862
effect of prior exposure to noninfected ticks on susceptibility of mice to lyme disease spirochetes.to determine whether prior exposure to nearctic ixodes vector ticks protects native reservoir mice from tick-borne infection by lyme disease spirochetes, we compared their infectivities for white-footed mice and laboratory mice that had been repeatedly infested by noninfected deer ticks. nymphal ticks readily engorged on tick-exposed laboratory mice, but their feeding success on white-footed mice progressively declined. tick-borne spirochetes readily infected previously tick-infested mice. thus, ...19989797328
characterization of an immunosuppressant protein from dermacentor andersoni (acari: ixodidae) salivary glands.a 36-kda soluble protein was found in the salivary glands of female dermacentor andersoni (stiles) ticks that suppressed the in vitro proliferative response of murine splenocytes to concanavalin a (con a). incubating the purified protein with splenocytes reduced the incorporation of thymidine into the dna of proliferating t-lymphocytes by more than 90% compared with cells exposed to con a and buffer alone. the n-terminal amino acid sequence of the immunosuppressant protein was determined to be n ...19989701936
development of a non-radioactive dna probe and in situ hybridization for detection of anaplasma marginale in ticks and cattle.a non-radioactive dna probe was developed for detection of anaplasma marginale in ticks and cattle. the probe was labeled with digoxigenin 11-dutp by polymerase chain reaction. the probe was tested on bovine blood and was found to be a sensitive and specific detection method for a. marginale in cattle. the dna probe was then adapted for in situ hybridization (ish) of a. marginale in dermacentor andersoni and d. variabilis ticks infected either as nymphs or adults. one-half of each tick was studi ...19989668458
in vitro susceptibilities of 27 rickettsiae to 13 antimicrobials.the mics of 13 antibiotics (doxycycline, thiamphenicol, rifampin, amoxicillin, gentamicin, co-trimoxazole, ciprofloxacin, pefloxacin, ofloxacin, erythromycin, josamycin, clarithromycin, and pristinamycin) were determined for 27 available rickettsial species or strains. we used two in vitro cell culture methods described previously: the plaque assay and the microplaque colorimetric assay. our results confirm the susceptibilities of rickettsiae to doxycycline, thiamphenicol, and fluoroquinolones. ...19989660979
phylogenetic placement of rickettsiae from the ticks amblyomma americanum and ixodes scapularis.a rickettsial isolate (isolate moaa) belonging to the spotted fever group (sfg) was obtained from the lone star tick amblyomma americanum. we used pcr to characterize the genes for the rickettsial outer membrane proteins rompa and rompb. we sequenced the pcr products (domains i of both the rompa gene and the rompb gene) of moaa and wb-8-2, another rickettsial isolate from a. americanum. to place moaa and wb-8-2 and two other nonpathogenic isolates (rickettsia rickettsii hip2 and rickettsia monta ...19989574696
taxonomic relationships among spotted fever group rickettsiae as revealed by antigenic analysis with monoclonal antibodies.the spotted fever group (sfg) is made up of more than 20 different rickettsial species and strains. study of the taxonomic relationships among the group has been attempted by phenotypic, genotypic, and phylogenetic analyses. in this study, we determined taxonomic relationships among the sfg rickettsiae by comparative analysis of immunogenic epitopes reactive against a panel of monoclonal antibodies. a total of 98 monoclonal antibodies, which were directed against epitopes on the major immunodomi ...19989542904
tick-borne diseases of sheep and goats caused by babesia, theileria or anaplasma spp.a review is given on the babesia, theileria, and anaplasma species infecting sheep and goats. b. ovis is the most important disease agent. it is transmitted by rhipicephalus bursa, r. turanicus, hyalomma anatolicum excavatum, and probably by r. evertsi evertsi b. ovis is widely spread in southern europe, the middle east, and central asia. its geographical distribution in south and east asia and in africa is widely unknown. b. motasi obviously represents several nosodemes in separate regions. it ...19979530692
granulocytic ehrlichiosis in tick-immune guinea pigs.we investigated whether ixodes scapularis-mediated host immunity interrupts transmission of the agent of human granulocytic ehrlichiosis (aohge) to guinea pigs. ticks infected with aohge readily transmitted aohge to tick-immune guinea pigs, despite incomplete tick engorgement and host attachment. although tick immunity can prevent lyme borreliosis, protection is not afforded against granulocytic ehrlichiosis.19989529119
detection of cattle naturally infected with anaplasma marginale in a region of endemicity by nested pcr and a competitive enzyme-linked immunosorbent assay using recombinant major surface protein 5.a competitive enzyme-linked immunosorbent assay using recombinant major surface protein 5 (rmsp5-celisa) of anaplasma marginale was validated in a naturally infected cattle herd in an area of eastern oregon where a. marginale is endemic. the true positive and negative a. marginale infection status of 235 randomly selected cattle was determined by using a nested pcr (npcr) coupled with msp5 sequence analysis and hybridization. judgment of the reliability of the npcr and hybridization for detectio ...19989508311
african swine fever virus infection in the argasid host, ornithodoros porcinus porcinus.the pathogenesis of african swine fever virus (asfv) infection in ornithodoros porcinus porcinus was examined in nymphal ticks infected with the asfv isolate chiredzi/83/1. at times postinfection (p.i.) ranging from 6 h to 290 days, ticks or dissected tick tissues were titrated for virus and examined ultrastructurally for evidence of virus replication. the asfv infection rate in ticks was 100% in these experiments, and virus infection was not associated with a significant increase in tick mortal ...19989499019
characterization of an endosymbiont infecting wood ticks, dermacentor andersoni, as a member of the genus francisella.a microorganism (dermacantor andersoni symbiont [das]) infecting rocky mountain wood ticks (d. andersoni) collected in the bitterroot mountains of western montana was characterized as an endosymbiont belonging to the genus francisella. previously described as wolbachia like, the organism's dna was amplified from both naturally infected tick ovarial tissues and vero cell cultures by pcr assay with primer sets derived from eubacterial 16s ribosomal dna (rdna) and francisella membrane protein genes ...19979327558
detection of colorado tick fever virus by using reverse transcriptase pcr and application of the technique in laboratory diagnosis.colorado tick fever (ctf) virus elicits an acute illness in humans, producing nonspecific flu-like symptoms and a biphasic fever in approximately 50% of patients. the disease is transmitted by the adult rocky mountain wood tick (dermacentor andersoni), and therefore incidence is limited by the habitat and life cycle of that vector. the early symptoms of infection are difficult to distinguish from those of several other agents, especially rickettsia rickettsii. serologic testing is usually unable ...19979114408
vector competence of ixodes scapularis, i. spinipalpis, and dermacentor andersoni (acari:ixodidae) in transmitting borrelia burgdorferi, the etiologic agent of lyme disease.this report describes the vector competence of 3 ixodid tick species, ixodes scapularis (say), i. spinipalpis (nuttall), and dermacentor andersoni (stiles), for borrelia burgdorferi in colorado. the study was based on preliminary field work performed in 6 colorado counties, where rodents and ticks were collected and assayed for the presence of b. burgdorferi. four of the 6 counties produced 52 rodent and 39 i. spinipalpis isolates of b. burgdorferi. two b. burgdorferi isolates were tested under ...19979103755
rickettsia peacockii sp. nov., a new species infecting wood ticks, dermacentor andersoni, in western montana.rickettsia peacockii, a new species of spotted fever group rickettsiae, was identified from rocky mountain wood ticks (dermacentor andersoni) collected in the sapphire mountain range on the eastern side of bitterroot valley, montana. dna from r. peacockii skalkahot (t = type strain) in naturally infected tick tissue was amplified by a pcr assay with primer sets derived from eubacterial 16s ribosomal dna (rdna), rickettsial citrate synthase, and 190-kda surface antigen (rompa) genes. partial 16s ...19979103635
developmental studies of anaplasma marginale (rickettsiales:anaplasmataceae) in male dermacentor andersoni (acari:ixodidae) infected as adults by using nonradioactive in situ hybridization and microscopy.the development of anaplasma marginale theiler was studied in ticks using a nonradioactive in situ hybridization method developed in our laboratory. male rocky mountain wood ticks, dermacentor andersoni stiles, were infected intrastadially by allowing them to feed for 7 d on an infected calf (acquisition feeding). the ticks were then removed and held in a humidity chamber for 5 d before being fed on a 2nd susceptible call for 10 d (transmission feeding). two groups of 10 ticks were collected dai ...19968961639
antibody against an anaplasma marginale msp5 epitope common to tick and erythrocyte stages identifies persistently infected cattle.a protein epitope of major surface protein 5 (msp5), defined by monoclonal antibody (mab) anaf16c1, is conserved among anaplasma species (e. s. visser, t. c. mcguire, g. h. palmer, w. c. davis, v. shkap, e. pipano, and d. p. knowles, jr., infect. immun. 60:5139-5144, 1992) and is expressed in the salivary glands of infected ticks. a competitive inhibition elisa (celisa) for the detection of bovine anti-msp5 antibodies was developed by using purified recombinant msp5 fusion protein and mab anaf16 ...19968862589
preliminary studies on the effect of anaplasma marginale antibodies ingested by dermacentor andersoni ticks (acari:ixodidae) with their blood meal on infections in salivary glands.the effect of anaplasma marginale antibodies ingested with the tick blood meal was tested on infected male ticks that were allowed to feed on cattle immunized with the erythrocytic stage of a. marginale. the experiments were done in two trials. trial 1 was done using splenectomized calves (two calves per treated and control groups) while ticks in trial 2 were fed on intact yearling cattle (four cattle per treated and control groups). the cattle were immunized with purified outer membrane protein ...19968674360
ecology of porcupines (erethizon dorsatum) and colorado tick fever virus in rocky mountain national park, 1975-1977.the involvement of porcupines, erethizon dorsatum (l.), in the ecology of colorado tick fever (ctf) virus in rocky mountain national park was investigated from 1975 to 1977. porcupine dens and feeding activity were found mostly on rocky knolls or on south-facing slopes within open stands of the montane coniferous forest, and 20 adult porcupines were trapped or captured by hand at those locations. an average of 24.6 +/- 5.4 adult dermacentor andersoni stiles ticks were found per animal (annual ra ...19938433332
development of anaplasma marginale in salivary glands of male dermacentor andersoni.development of the rickettsia, anaplasma marginale, in salivary glands of male dermacentor andersoni exposed as nymphs or adult ticks, was studied indirectly by inoculation of susceptible calves with homogenates and directly by examination, using light microscopy and a dna probe; some unfed ticks were incubated before tissues were collected. salivary gland homogenates made from ticks in every treatment group caused anaplasmosis when injected into susceptible calves; prepatent periods decreased a ...19938427453
impact of persistent anaplasma marginale rickettsemia on tick infection and transmission.anaplasma marginale, an intraerythrocytic rickettsia of cattle, is transmitted biologically by ticks. because of the brevity of acute a. marginale infection, transmission may rely on the tick's ability to acquire the organism from persistently infected cattle with low rickettsemia levels. by using a nucleic acid probe to quantitate low-level infection, we found that rickettsemia levels in persistently infected cattle fluctuated at approximately 5-week intervals during a 24-week period, from < 10 ...19938370734
detection of anaplasma marginale (rickettsiales: anaplasmataceae) in secretagogue-induced oral secretions of dermacentor andersoni (acari: ixodidae) with the polymerase chain reaction.the polymerase chain reaction (pcr) was used to detect anaplasma marginale in secretagogue-induced oral secretions of male and female dermacentor andersoni stiles exposed as nymphs or adults by feeding on infected calves. a 409-bp dna fragment derived from the a. marginale (florida isolate) msp1 beta gene was amplified with oligonucleotide primers bap-2 (5'-gtatggcacgtagtcttgggatca-3') and al34s (5'-cagcagcagcaagaccttca-3'). the target dna was amplified in oral secretions of female ticks exposed ...19938360903
detection of anaplasma marginale (rickettsiales: anaplasmataceae) in hemolymph of dermacentor andersoni (acari: ixodidae) with the polymerase chain reaction.the polymerase chain reaction (pcr) was used to detect anaplasma marginale in hemolymph collected from live dermacentor andersoni stiles ticks. hemolymph was collected from severed legs of male and female ticks exposed to a. marginale as either nymphs or adults. heat treatment was found to be the optimum method of hemolymph preparation for pcr. hemolymph samples were collected and pooled from adult ticks exposed as nymphs on days 0-10 of feeding on a susceptible calf. for male and female ticks e ...19938360902
acquired resistance of guinea pigs to dermacentor andersoni mediated by humoral factors.humoral and cell-mediated immune resistance to tick infestation has been documented in many host-parasite relationships. this study examines passive transfer of resistance to dermacentor andersoni expressed by recipients of serum pools derived from guinea pigs that had acquired resistance through experimental infestation. recipients of sera from high titer adult-infested animals expressed resistance evidenced by reduced engorgement weights, histological changes at tick attachment sites, and tick ...19938277384
persistence of tick-derived anaplasma marginale in cultured bovine turbinate and endothelial cells.anaplasma marginale from salivary glands of dermacentor andersoni was used to inoculate monolayers of bovine turbinate and endothelial cells. monolayers were passaged at 2 or 4 week intervals and monitored with light and electron microscopy and with an a. marginale-specific dna probe. intracellular inclusions were observed in turbinate cells after 2-4 weeks. the number of inclusion-bearing cells increased over 1-2 weeks and gradually disappeared. a radiolabeled fragment from within the msp1 beta ...19938134656
dna typing of rickettsiae in naturally infected ticks using a polymerase chain reaction/restriction fragment length polymorphism system.we used the polymerase chain reaction/restriction fragment length polymorphism (pcr/rflp) rickettsial typing system of regnery and others to rapidly identify rickettsiae in naturally infected ticks. unlike previously described methods, our pcr assays type rickettsiae directly from tick tissues without first isolating the organisms. we collected 226 adult dermacentor andersoni ticks in the bitterroot mountains of western montana and analyzed them for possible rickettsial infection by hemolymph te ...19947906924
molecular and biological characterization of a newly isolated anaplasma marginale strain.anaplasma marginale, a rickettsial hemoparasite of cattle and other ruminants, results in significant economic losses worldwide. distinct strains of a. marginale have been identified based on differences in tick transmissibility, molecular size of surface proteins and dna restriction fragments, and reactivity to a panel of monoclonal antibodies. these different strains vary considerably in their virulence, antigenic composition, and ability to protect against heterologous challenge. in this pape ...19947858023
effects of dermacentor andersoni (acari: ixodidae) salivary gland extracts on bos indicus and b. taurus lymphocytes and macrophages: in vitro cytokine elaboration and lymphocyte blastogenesis.cattle and laboratory animal species-acquired resistance to tick infestation has an immunological basis involving antigen presenting cells, b-lymphocytes, t-lymphocytes, and cytokines. tick infestation has been shown to impair guinea pig antibody responses to a thymic-dependent antigen and in vitro responsiveness of lymphocytes to t-cell mitogens. tick salivary gland extracts inhibited in vitro proliferative responses of normal murine lymphocytes to the t-cell mitogen concanavalin a (con a) and ...19957616525
tick paralysis in two llamas.an 18-month-old sexually intact male llama and a 7-month-old female llama were examined because of weakness, lethargy, and recumbency. both had signs of ascending motor paralysis with minimal or no afferent sensory loss. tick paralysis was diagnosed on the basis of complete clinical recovery following removal of a single, attached and engorged female tick (dermacentor andersoni) from each llama. the male llama recovered within a few hours after removal of the tick, but recovery in the female lla ...19957591950
mosquito sensitivity to a scorpion neurotoxin expressed using an infectious sindbis virus vector.the scorpion, androctonus australis hector, produces an insect-specific toxin (aahit) encoded by the scotox gene. to assess the toxicity of aahit for mosquitoes, we have taken a novel approach to express the scotox gene in vivo. we have engineered a double subgenomic sindbis (dssin) virus that contains the scotox gene in the viral genome and intrathoracically inoculated the virus (te/3'2j/scotox) into mosquitoes (aedes aegypti, ae. triseriatus and culex pipiens), houseflies (musca domestica) and ...19957551198
evidence of common and genus-specific epitopes on ornithodoros spp. tick (acari: argasidae) salivary proteins.new zealand white rabbits were repeatedly infested with ornithodoros turicata (duges), ornithodoros talaje (guérin-méneville), and ornithodoros coriaceus (koch) at 2-wk intervals. blood samples were taken from each animal 10 d after each infestation and the titer of anti-tick antibody was determined by enzyme-linked immunosorbent assay. subsequent cross-reactivity studies demonstrated that the antitick antisera nonspecifically bound to salivary gland extract proteins prepared from several other ...19957544412
dermacentor andersoni: salivary gland proteins suppressing t-lymphocyte responses to concanavalin a in vitro.salivary glands obtained from feeding adult female dermacentor andersoni (acari:ixodidae) were fractionated using differential centrifugation, detergents, centrifugal concentrators incorporating filter membranes with various molecular weight cutoffs, and preparative sds-page. a lymphocyte proliferation assay was used to evaluate the effects of salivary gland fractions on cona-induced blastogenesis of normal murine splenocytes. lipid, soluble, and detergent-soluble fractions were found to signifi ...19957498423
the role of cottontail rabbits (sylvilagus spp.) in the ecology of rickettsia rickettsii in the united states.rocky mountain (sylvilagus nuttallii) and eastern (s. floridanus) cottontails were examined for their susceptibility to virulent and avirulent strains of the spotted fever agent, rickettsia rickettsii. both species of rabbits responded to inoculation of yolk sac suspensions containing 500 egg ld50 of either virulent or avirulent rickettsiae, with rickettsemias detectable as early as 3 days after inoculation and lasting up to 7 days. when fed upon by infected ticks, only one of three rocky mounta ...19807406116
chemoprophylaxis of vector-borne anaplasmosis with sustained-release boluses.sustained-release oxytetracycline boluses (20%) delivering 145 to 150 mg/bolus/day were administered to complement-fixation test-negative cattle at dosages of 2.0, 2.5, and 3.0 mg/kg of body weight. subsequent challenge exposure of cattle with dermacentor andersoni stiles infected with anaplasma marginale theiler indicated that treatment with the dosage of 2.5 mg/kg prevented clinical anaplasmosis and that treatment with the dosage of 3.0 mg/kg prevented disease infection.19817340579
resistance and cross-resistance of guinea pigs to dermacentor andersoni stiles, d. variabilis (say), amblyomma americanum (linnaeus), and ixodes scapularis say.the ability of guinea pigs to acquire resistance to dermacentor andersoni and amblyomma americanum was determined by repeatedly infesting separate sets of guinea pigs with tick larvae. resistance was measured in terms of reduced numbers successfully engorging and reduced weight of those ticks that engorged. an 83% reduction in numbers of larvae engorging and a 64.5% reduction in the weight of engorged larvae were seen between the first and second infestations with d. andersoni. guinea pigs exhib ...19817328454
bilateral gynandromorphism in dermacentor andersoni (acari: ixodidae): morphologic and cytogenetic analysis. 19817288835
transmission of anaplasma marginale theiler by dermacentor andersoni stiles and dermacentor variabilis (say).cattle were inoculated with a virginia isolate of anaplasma marginale theiler and served as an infective source for laboratory-reared dermacentor andersoni stiles and d variabilis (say) nymphs. following a molt and subsequent feeding of adult ticks on susceptible cows, transstadial transmission of a marginale occurred from cattle with parasitemias ranging from undetectable (in a carrier cow) to a peak of 27% (in an acutely ill cow). homogenates of gut tissue from unfed, incubated, and feeding ad ...19817224310
ultrastructure of anaplasma marginale theiler in dermacentor andersoni stiles and dermacentor variabilis (say).cattle were inoculated with a virginia isolate of anaplasma marginale theiler and served as an infective source for laboratory-reared dermacentor andersoni stiles and d variabilis (say) nymphs. anaplasma marginale was demonstrated by electron microscopy in gut tissues of replete nymphal ticks and in unfed, incubated, and feeding adult ticks that were exposed to the organism as nymphs when they fed on an infected cow. the a marginale organism in replete nymphs and adult feeding ticks were morphol ...19807212430
the induction of host resistance to tick infestation with a salivary gland antigen.salivary gland antigen, sga, derived from partially engorged female dermacentor andersoni was shown to be capable of inducing resistance to tick infestation in guinea pigs never previously exposed to ticks. immunization regimens involved the administration of sga by different routes and with or without the use of adjuvants. induced resistance was expressed by significantly fewer larvae engorging, and the weight of larvae which did engorge was reduced. salivary gland antigen has been shown to int ...19817212171
dermacentor variabilis and dermacentor andersoni: genital sex pheromones. 19827151942
immune responsiveness of the bovine host to repeated low-level infestations with dermacentor andersoni. 19827149833
guanine biosynthesis in the ticks (acari) dermacentor andersoni (ixodidae) and argas (persicargas) arboreus (argasidae): fate of labelled guanine precursors. 19827143379
quinone inhibition of sex pheromone activity in the ticks dermacentor andersoni stiles and dermacentor variabilis (say).disruption of sex pheromone activity in female rocky mountain wood ticks, dermacentor andersoni stiles, and american dog ticks, dermacentor variabilis (say), was achieved by treatment with the quinones para-benzoquinone and menadione. the most effective treatments were those administered by inoculation to unfed, mature, adult females prior to feeding. inoculation of p-benzoquinone was also effective when administered to feeding ticks, from 2 to 5 days after they had attached, though not to the s ...19827131198
survey for evidence of colorado tick fever virus outside of the known endemic area in california.a virus very similar or identical to colorado tick fever (ctf) virus was recovered from the blood clot of one of 104 black-tailed jack rabbits (lepus californicus) examined during a survey for various zoonotic agents in mammals and ticks from the university of california, hopland field station, mendocino county, california, 1974--79. this is the first reported isolation of a ctf-like virus from l. californicus, and only the second time such a virus has been found in northwestern california. mend ...19827102919
influence of increased temperature on anaplasma marginale theiler in the gut of dermacentor andersoni stiles.three splenectomized dairy calves were inoculated with a virginia isolate of anaplasma marginale theiler and served as an infective source for laboratory-reared dermacentor andersoni stiles nymphs. one month after molting, groups of adult ticks were incubated at 37 c for 0, 1.5, 2.5, and 7 days. gut homogenates were made from ticks representing each incubation period. twenty-four susceptible, splenectomized dairy calves were each inoculated iv with a gut homogenate extracted from 50 adult ticks ...19827091815
morphologic characteristics of colonies of anaplasma marginale theiler in midgut epithelial cells of dermacentor andersoni stiles.colonies of anaplasma marginale theiler were studied in midgut epithelial cells of adult dermacentor andersoni stiles that were infected as nymphs. colonies were categorized by light microscopy into 5 morphologic types that appear to represent stages in a developmental sequence. the mean diameter of the colony types ranged from 5.64 micrometer to type 1 colonies to 10.49 micrometers of type 5 colonies. representatives of each colony type were selected by light microscopy and were sectioned for e ...19827073078
observations on the behaviour of dermacentor andersoni larvae infesting normal and tick resistant guinea-pigs.in three separate experiments the behaviour of dermacentor andersoni larvae on normal and tick-resistant guinea-pigs was studied at intervals throughout 5-day infestation periods. fewer larvae survived on resistant hosts and their mean sizes were less than those of larvae on normal hosts, the differences becoming more obvious as time progressed. when measured at 32 degrees c, the peristaltic rates of midgut diverticula of the larvae surviving on resistant hosts were consistently lower than those ...19827070838
demonstration of anaplasma marginale theiler in ticks by tick transmission, animal inoculation, and fluorescent antibody studies.cattle were inoculated with a virginia isolate of anaplasma marginale theiler and served as an infective source for laboratory-reared dermacentor andersoni stiles and d variabilis (say) nymphs. transstadial transmission of a marginale was demonstrated by feeding the newly molted adult ticks of both species on susceptible cattle and by inoculation of gut and salivary gland homogenates collected from adult ticks at postattachment days 5 and 7. oral secretions collected from the same group of ticks ...19806989298
influence of dermacentor andersoni infestation on lymphocyte responsiveness to mitogens. 19826985018
in vitro feeding of dermacentor andersoni (stiles): effects of histamine and other mediators.female dermacentor andersoni were induced to feed on defibrinated bovine blood through fixed mouse skin membranes. their feeding behaviour was recorded electronically, the tick being incorporated into the circuit and acting as a variable resistor during the periods of sucking, salivation and rest. recordings of the feeding behaviour of these ticks were similar to those of ticks feeding on rabbits. known concentrations of histamine, serotonin, dopamine, prostaglandin e1 and prostaglandin f2a were ...19836877868
artificial feeding of adult and nymphal dermacentor andersoni (acari: ixodidae) during studies on bovine anaplasmosis. 19836876089
influence of parasitemia level at feeding on development of anaplasma marginale theiler in dermacentor andersoni stiles.four splenectomized dairy calves were inoculated with a virginia isolate of anaplasma marginale theiler and served as an infective source (donor) for laboratory-reared dermacentor andersoni stiles nymphs. two donor calves developed higher parasitemias during tick feeding than did the 2 other donor calves. one month after molting, adult ticks were incubated at 37 c for 2.5 days to stimulate development of colonies of a marginale, and homogenates of gut were made from ticks fed on each donor calf. ...19836869951
seasonal activity and colorado tick fever virus infection rates in rocky mountain wood ticks, dermacentor andersoni (acari: ixodidae), in north-central colorado, usa. 19836827573
reactivation of rickettsia rickettsii in dermacentor andersoni ticks: an ultrastructural analysis.virulent rickettsia in dermacentor andersoni lose their pathogenicity and virulence for guinea pigs when subjected to physiological stresses, such as starvation (overwintering), of its tick vector. however, incubation of infected ticks at an elevated temperature (37 degrees c) for 24 to 48 h or feeding for a time (usually greater than 10 h) induces r. rickettsii to revert to a virulent state, a phenomenon defined as "reactivation." electron microscopy reveals that the microcapsular and slime lay ...19826811439
serotypes of spotted fever group rickettsiae isolated from dermacentor andersoni (stiles) ticks in western montana.adult dermacentor andersoni ticks were collected by flagging vegetation in 18 canyons bordering the bitterroot valley, montana, an area where nearly 400 cases of rocky mountain spotted fever (rmsf) have occurred since 1900. three hundred and nine (8.3%) of the 3,705 ticks collected contained hemocyte-associated rickettsia-like organisms of three morphologic types, coccobacillary, fine bacillary, and coarse bacillary (long forms). only the coccobacillary and fine bacillary organisms stained with ...19816782899
pheromone-induced aggregation of ixodid ticks before host contact.the presence of a pre-feeding aggregation pheromone was demonstrated in the species dermacentor variabilis, dermacentor andersoni, dermacentor parumapertus, amblyomma americanum and haemaphysalis leporispalustris by assay within a petri dish. however, amblyomma maculatum and amblyomma cajennense did not aggregate in the sector containing discs of presumed pheromone within the hour period. d. andersoni and a. americanum recognized each other's pheromone and a. americanum recognized that of h. lep ...19836683667
tularaemia transmitted by ticks (dermacentor andersoni) in saskatchewan.common wood ticks (dermacentor andersoni) collected from saskatchewan landing provincial park, saskatchewan in the spring of 1982 transmitted a lethal tularaemia infection to four of six rabbits. francisella tularensis organisms were isolated from tissues taken from the dead rabbits and identified from subcultures using an indirect immunofluorescent antibody assay. one human associated with the animals developed symptoms of tularaemia and, after successful therapy, had a significant increase in ...19836667429
demonstration of colonies of anaplasma marginale in the midgut of rhipicephalus simus.rhipicephalus simus nymphs were allowed to feed on a cow experimentally infected with the bw-strain of anaplasma marginale from republic of south africa, and they were studied as adults. colonies were demonstrated by light microscopy in midgut epithelial cells of adult ticks that were unfed (as adults), incubated, or prefed for 72 hours on a cow. the colonies occurred in 5 different morphologic types (1 to 5) that were similar to those described previously for a virginia isolate of a marginale i ...19836660614
radiorespirometric determination of contribution of pentose phosphate cycle to metabolism of glucose in dermacentor andersoni. 19836631086
development of colonies of anaplasma marginale in the gut of incubated dermacentor andersoni. 19836625314
some aspects of organic acid metabolism in dermacentor andersoni female. 19846512290
demonstration of the inclusion appendage of anaplasma marginale in nymphal dermacentor andersoni.dermacentor andersoni nymphs were placed in stockinettes and allowed to feed on a splenectomized calf with experimentally induced anaplasmosis when the parasitemia was 3%-5%. nymphs were selected on each of the 6 days of feeding and every 5 days from repletion through molting to the adult stage (25 days postrepletion); they were killed and midgut tissues were processed and examined by light and electron microscopies. no stages of a marginale were seen in tissues of feeding ticks. visualization o ...19846497136
biochemical and immunochemical analysis of rickettsia rickettsii strains of various degrees of virulence.six strains of rickettsia rickettsii from montana and north carolina were examined in an effort to identify rickettsial constituents associated with virulence. fever responses, scrotal reactions, and mortalities of male guinea pigs inoculated intraperitoneally with 1,000 pfu of rickettsial strains revealed that the two montana patient strains ( sheila smith and norgaard ) and one montana strain ( sawtooth female 2) from the wood tick, dermacentor andersoni, could be placed in the group of highes ...19846427110
demonstration of anaplasma marginale in hemolymph of dermacentor andersoni by animal inoculation and by fluorescent-antibody technique.hemolymph was collected from adult dermacentor andersoni stiles that had been infected with anaplasma marginale theiler as nymphs. before hemolymph was collected, the adult ticks were either incubated and unfed at 37 c for 2.5 days or fed for 6 days on sheep. hemolymph collected from groups of 100 ticks was inoculated into susceptible splenectomized calves. smears of hemolymph from the same groups of ticks were prepared for examination by fluorescent antibody technique. hemolymph from incubated ...19836346968
immunocytochemical labeling of anaplasma marginale theiler in dermacentor andersoni stiles with peroxidase- antiperoxidase technique.colonies of anaplasma marginale in midgut epithelial cells of adult ticks that had been infected as nymphs were specifically labeled, using the unlabeled antibody peroxidase-antiperoxidase method of immunocytochemistry. visual comparison of infected and control tissue sections with the electron microscope demonstrated deposition of ring-like peroxidase-antiperoxidase complexes over organisms within the colonies. the intensity of labeling differed among organisms within a single colony, possibly ...19826285774
the ecology of colorado tick fever in rocky mountain national park in 1974. ii. infection in small mammals.field studies of colorado tick fever (ctf) in small mammals in rocky mountain national park (rmnp) in 1974 established that eutamias minimus and spermophilus lateralis were the most important hosts for ctf virus and were the source of virus for immature stages of the tick vector, dermacentor andersoni. other species (peromyscus maniculatus, spermophilus richardsonii, eutamias umbrinus) are secondary hosts. the intensity of viral activity in rodents varied greatly from locality to locality. highe ...19816263122
significant changes in epidermal langerhans cells of guinea-pigs infested with ticks (dermacentor andersoni).resistance to tick feeding has previously been shown to be an acquired, immunologically mediated phenomenon in guinea-pigs, associated with cutaneous basophil hypersensitivity to tick antigens. in this study, langerhans cells (lc) in the epidermis of guinea-pigs were monitored during tick infestations of susceptible and resistant animals. a specific adenosine triphosphatase (atpase) staining technique was used to identify epidermal lc. the numbers of lc decreased significantly around the sites o ...19846228517
staining characteristics of colonies of anaplasma marginale theiler in dermacentor andersoni stiles.colonies of anaplasma marginale theiler were studied in midgut epithelial cells of adult dermacentor andersoni stiles that were infected as nymphs. the colonies were demonstrated in plastic sections (1 micrometer) and frozen sections (6 micrometer) with mallory's stain. colonies were also demonstrated in frozen sections, using direct fluorescent antibody technique. colonies were not observed in plastic or frozen sections stained by the giménez method. in all preparations, the colonies were usual ...19816175257
growth of colorado tick fever (ctf) virus in primary tissue cultures of its vector, dermacentor andersoni stiles (acarina: ixodidae), with notes on tick tissue culture. 19676073593
collection of dermacentor andersoni (stiles) with carbon dioxide and its application in studies of colorado tick fever virus. 19655841585
phenology, behavior, and host-relations of dermacentor andersoni stiles in outdoor "rodentaria" and in nature. 19685749472
effects of vitamin a deficiency and ked resistance on the feeding of dermacentor andersoni on sheep. 19685690045
occurrence of colorado tick fever virus in dermacentor andersoni ticks in british columbia. 19685667781
attempts to transmit bovine anaplasmosis with anopheles quadrimaculatus say (diptera: culicidae) and dermacentor andersoni stiles (acarina: ixodidae). 19705485390
anaplasmosis. xix. a preliminary study of anaplasma marginale in dermacentor andersoni (stiles) by fluorescent antibody technique. 19665335865
ecology of tick vectors of american spotted fever.the author reviews the natural history of the tick vectors of american spotted fever. the discussion concerns the ecology of the rocky mountain wood tick, dermacentor andersoni, the american dog tick, dermacentor variabilis, and the lone-star tick, amblyomma americanum, all of which are proven vectors of rocky mountain spotted fever to man. also included are the rabbit tick, haemaphysalis leporispalustris and dermacentor parumapertus, which very rarely bite man but which are considered of import ...19695306621
natural history of tick-borne spotted fever in the usa. susceptibility of small mammals to virulent rickettsia rickettsii.in the ecology of spotted fever rickettsiae, one of the as yet unsolved problems concerns the significance of small animals in the distribution of rickettsia rickettsii in nature. in the bitter root valley of western montana, a great variety of rodents, rabbits and hares are known to serve as the preferred hosts for the immature stages of the vector tick, dermacentor andersoni.the authors analyse the susceptibility of various species of small mammals to virulent r. rickettsii and evaluate their ...19665296999
transstadial (nymph-to-adult) infection of anaplasma marginale in dermacentor andersoni stiles. 19715160254
gross anatomical, histological, and cytological aspects of ovarian development in dermacentor andersoni (stiles (acari: ixodidae). 19715105959
sites of attachment of 'prairie' and 'montane' dermacentor andersoni (acarina: ixodidae) on cattle. 19725036197
localization of powassan virus in dermacentor andersoni ticks by immunofluorescence. 19694905045
biochemical and physiological studies of certain ticks (ixodoidea): isolation and partial identification of a new fatty acid in eggs of dermacentor andersoni stiles (ixodidae). 19744837887
biochemical and physiological studies of certain ticks (ixodoidea). fatty acid composition of the female, eggs, and larva of dermacentor andersoni (stiles) (ixodidae). 19734744042
creatine phosphokinase elevation in a case of tick paralysis.the results of studies on a case of tick paralysis in a female child are described. the patient was paralysed by a single female specimen of dermacentor andersoni stiles attached to the left temporal area of the scalp. paralysis of the lower limbs, incoordinate respiration and weakness of the arms were evident.the findings on physical examination and the results of diagnostic laboratory procedures are reported and the possible significance of the results is discussed. the only abnormal laborator ...19734707234
fine structure of normal hemocytes in dermacentor andersoni stiles (acari:ixodidae). 19714332374
fine structure of oogonial and oocyte development in dermacentor andersoni stiles (acari: ixodidae). 19714327965
isolation and characterization of symbiotes from the rocky mountain wood tick, dermacentor andersoni. 19734202564
recognition of anaplasma marginale theiler in dermacentor andersoni stiles (=d. venustus marx) by the fluorescent antibody method. i. smears of nymphal organs. 19704189907
a proposed site of fluid secretion in the salivary gland of the ixodid tick dermacentor andersoni. 19734127146
fine structure of rickettsia canada in tissues of dermacentor andersoni stiles.preliminary observations on growth and developmental fine structure of rickettsia canada in various organs and tissues of the hard tick, dermacentor andersoni stiles, are reported. r. canada is typically rod-shaped, being delimited with a three-layered wall having a velvety coating adsorbed to its exterior surface. a finely reticulated cytoplasmic matrix containing prominent ribosomes is delimited with a three-layered unit membrane. average length and width of these organisms are 1.6 by 0.4 mum. ...19714100833
resistance to ixodid tick infestation induced by administration of tick-tissue culture cells.primary tissue culture cells of developing larvae of amblyomma americanum were administered to guinea-pigs never previously exposed to ixodid ticks. guinea-pigs were given 1 x 10(6) primary culture cells on days 0, 7 and 21 by subcutaneous injection and challenged with male and female a. americanum on day 35. a significant degree of induced host tick resistance was expressed by reduced engorgement weight of females, reduced oviposition by those females which did obtain a blood meal, and by death ...19854083961
transmission of anaplasma marginale by adult dermacentor andersoni during feeding on calves.laboratory-reared dermacentor andersoni ticks experimentally infected as nymphs with anaplasma marginale were allowed to feed as adults from 1 to 9 days on susceptible, splenectomized calves to determine when, during feeding, the hematozoan was transmitted from ticks to cattle. in experiment 1, ticks were allowed to feed on calves for 1, 2, 3, 4, 5, or 6 days and anaplasmosis did not result. the same calves were used for experiment 2, and ticks were allowed to feed for 1, 3, 6, 7, 8, or 9 days a ...19854026042
Refresh
firstprev
123456
nextlast
Displaying items 401 - 500 of 562