Publications
| Title | Abstract | Year(sorted descending) Filter | PMID Filter |
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| meeting the challenges of on-host and off-host water balance in blood-feeding arthropods. | in this review, we describe water balance requirements of blood-feeding arthropods, particularly contrasting dehydration tolerance during the unfed, off-host state and the challenges of excess water that accompany receipt of the bloodmeal. most basic water balance characteristics during the off-host stage are applicable to other terrestrial arthropods, as well. a well-coordinated suite of responses enable arthropods to conserve water resources, enhance their desiccation tolerance, and increase t ... | 2010 | 20206630 |
| epidemiology of colorado tick fever in montana, utah, and wyoming, 1995-2003. | colorado tick fever (ctf) is a biphasic, febrile illness caused by a coltivirus and transmitted by the rocky mountain wood tick, dermacentor andersoni, in the western united states and canada. symptoms generally include acute onset of fever, headache, chills, and myalgias; illness often lasts for 3 weeks or more. laboratory-confirmed cases of ctf were identified from public health department records in montana, utah, and wyoming, and from the centers for disease control and prevention diagnostic ... | 2010 | 19725767 |
| blood feeding by the rocky mountain spotted fever vector, dermacentor andersoni, induces interleukin-4 expression by cognate antigen responding cd4+ t cells. | abstract: | 2009 | 19814808 |
| superinfection occurs in anaplasma phagocytophilum infected sheep irrespective of infection phase and protection status. | anaplasma phagocytophilum infection in domestic ruminants is widespread in the coastal areas of southern norway. the bacteria may persist in mammalian hosts. several genetic variants of a. phagocytophilum exist. in the present study, we investigate whether superinfection occurs in the acute and persistent phase of the infection. | 2009 | 19857248 |
| major histocompatibility complex (mhc) heterozygote superiority to natural multi-parasite infections in the water vole (arvicola terrestris). | the fundamental role of the major histocompatibility complex (mhc) in immune recognition has led to a general consensus that the characteristically high levels of functional polymorphism at mhc genes is maintained by balancing selection operating through host-parasite coevolution. however, the actual mechanism by which selection operates is unclear. two hypotheses have been proposed: overdominance (or heterozygote superiority) and negative frequency-dependent selection. evidence for these hypoth ... | 2009 | 19129114 |
| conservation in the face of diversity: multistrain analysis of an intracellular bacterium. | with the recent completion of numerous sequenced bacterial genomes, notable advances have been made in understanding the level of conservation between various species. however, relatively little is known about the genomic diversity among strains. we determined the complete genome sequence of the florida strain of anaplasma marginale, and near complete (>96%) sequences for an additional three strains, for comparative analysis with the previously fully sequenced st. maries strain genome. | 2009 | 19134224 |
| prevalence of rickettsia species in canadian populations of dermacentor andersoni and d. variabilis. | we determined the prevalence of rickettsiae in dermacentor adults at 15 localities in canada. rickettsia rickettsii was not detected in any tick, whereas rickettsia peacockii was present in 76% of dermacentor andersoni adults and rickettsia montanensis in 8% of dermacentor variabilis adults. this host specificity was maintained in localities where both tick species occurred in sympatry. | 2009 | 19151178 |
| independence of anaplasma marginale strains with high and low transmission efficiencies in the tick vector following simultaneous acquisition by feeding on a superinfected mammalian reservoir host. | strain superinfection occurs when a second pathogen strain infects a host already carrying a primary strain. anaplasma marginale superinfection occurs when the second strain carries a variant repertoire different from that of the primary strain, and the epidemiologic consequences depend on the relative efficiencies of tick-borne transmission of the two strains. following strain superinfection in the reservoir host, we tested whether the presence of two a. marginale (sensu lato) strains that diff ... | 2009 | 19188360 |
| suppression of cell proliferation and cytokine expression by hl-p36, a tick salivary gland-derived protein of haemaphysalis longicornis. | previously, a putative immunosuppressant-coding gene was identified from a complementary dna library derived from the salivary glands of partially-fed haemaphysalis longicornis. using real-time polymerase chain reaction, the gene was shown to be predominantly expressed during blood feeding with the site of expression being mainly in the salivary glands; this was confirmed by western blotting analysis. to investigate the function of this novel protein, in this study, we examined the proliferative ... | 2009 | 18624730 |
| detection of tick-borne pathogens by masstag polymerase chain reaction. | masstag polymerase chain reaction (pcr) is a platform that enables microbe detection using primers labeled through a photocleavable link with tags that vary in molecular weight. after multiplex pcr, tags are released by ultraviolet irradiation and analyzed by mass spectroscopy. the identification of a microbe in a sample is determined by its cognate tags. here we describe establishment and implementation of a masstag pcr panel for surveillance of microbes implicated in tick-vectored infectious d ... | 2009 | 18800864 |
| francisella tularensis: an arthropod-borne pathogen. | arthropod transmission of tularemia occurs throughout the northern hemisphere. few pathogens show the adaptability of francisella tularensis to such a wide array of arthropod vectors. nonetheless, arthropod transmission of f. tularensis was last actively investigated in the first half of the 20th century. this review will focus on arthropod transmission to humans with respect to vector species, modes of transmission, geographic differences and f. tularensis subspecies and clades. | 2009 | 18950590 |
| quantitative differences in salivary pathogen load during tick transmission underlie strain-specific variation in transmission efficiency of anaplasma marginale. | the relative fitness of arthropod-borne pathogens within the vector can be a major determinant of pathogen prevalence within the mammalian host population. strains of the tick-borne rickettsia anaplasma marginale differ markedly in transmission efficiency, with a consequent impact on pathogen strain structure. we have identified two a. marginale strains with significant differences in the transmission phenotype that is effected following infection of the salivary gland. we have proposed competin ... | 2009 | 18955472 |
| dermatologic changes induced by repeated ixodes scapularis bites and implications for prevention of tick-borne infection. | previous studies in rodents and people have demonstrated that repeated tick exposure is associated with reduced borrelia burgdorferi transmission but the mechanism of prevention remains unclear. we examined the acute histopathologic reactions to initial and repeated ixodes scapularis bites in balb/c mice and in people. skin biopsies of balb/c mice infested for the first time by i. scapularis nymphs revealed vascular dilatation and an accumulation of inflammatory cells adjacent to the bite site b ... | 2009 | 19196014 |
| allopatric speciation in ticks: genetic and reproductive divergence between geographic strains of rhipicephalus (boophilus) microplus. | the cattle tick, rhipicephalus (boophilus) microplus, economically impact cattle industry in tropical and subtropical regions of the world. the morphological and genetic differences among r. microplus strains have been documented in the literature, suggesting that biogeographical and ecological separation may have resulted in boophilid ticks from america/africa and those from australia being different species. to test the hypothesis of the presence of different boophilid species, herein we perfo ... | 2009 | 19243585 |
| nonrandom distribution of vector ticks (dermacentor variabilis) infected by francisella tularensis. | the island of martha's vineyard, massachusetts, is the site of a sustained outbreak of tularemia due to francisella tularensis tularensis. dog ticks, dermacentor variabilis, appear to be critical in the perpetuation of the agent there. tularemia has long been characterized as an agent of natural focality, stably persisting in characteristic sites of transmission, but this suggestion has never been rigorously tested. accordingly, we sought to identify a natural focus of transmission of the agent ... | 2009 | 19247435 |
| cell lines from the soft tick ornithodoros moubata. | primary cell cultures (n = 16) were initiated from tissues of embryonic and neonatal larval ornithodoros moubata following methods developed for hard ticks. after maintenance for 20-25 months in vitro, cell multiplication commenced in surviving cultures, leading to the establishment of six cell lines designated ome/ctvm21, 22, 24, 25, 26 and 27. all lines are maintained at 28 degrees c, with subculture at 2-8 week intervals. the cultures comprise heterogeneous populations of large cells of 15-10 ... | 2009 | 19252822 |
| ecological fitness and strategies of adaptation of bartonella species to their hosts and vectors. | bartonella spp. are facultative intracellular bacteria that cause characteristic hostrestricted hemotropic infections in mammals and are typically transmitted by blood-sucking arthropods. in the mammalian reservoir, these bacteria initially infect a yet unrecognized primary niche, which seeds organisms into the blood stream leading to the establishment of a long-lasting intra-erythrocytic bacteremia as the hall-mark of infection. bacterial type iv secretion systems, which are supra-molecular tra ... | 2009 | 19284965 |
| a novel sphingomyelinase-like enzyme in ixodes scapularis tick saliva drives host cd4 t cells to express il-4. | tick feeding modulates host immune responses. tick-induced skewing of host cd4(+) t cells towards a th2 cytokine profile facilitates transmission of tick-borne pathogens that would otherwise be neutralized by th1 cytokines. tick-derived factors that drive this th2 response have not previously been characterized. in the current study, we examined an i. scapularis cdna library prepared at 18-24 h of feeding and identified and expressed a tick gene with homology to loxosceles spider venom proteins ... | 2009 | 19292772 |
| cattle can develop immunity to paralysis caused by dermacentor andersoni. | cattle exposed to a paralyzing strain of dermacentor andersoni (stiles) were all paralyzed during an initial exposure, but the incidence of paralysis decreased to 17 and 0% after two subsequent exposures to virulent flat ticks. cattle with a single exposure to paralyzing ticks became paralyzed when challenged with ticks that had been prefed on cattle. western blots indicated that cattle developed antibody responses to 13 antigens in paralyzing tick saliva. the likelihood of paralysis was inverse ... | 2009 | 19351088 |
| the relationship between spotted fever group rickettsiae and ixodid ticks. | spotted fever group rickettsiae are predominantly transmitted by ticks. rickettsiae have developed many strategies to adapt to different environmental conditions, including those within their arthropod vectors and vertebrate hosts. the tick-rickettsiae relationship has been a point of interest for many researchers, with most studies concentrating on the role of ticks as vectors. unfortunately, less attention has been directed towards the relationship of rickettsiae with tick cells, tissues, and ... | 2009 | 19358804 |
| reviewing molecular adaptations of lyme borreliosis spirochetes in the context of reproductive fitness in natural transmission cycles. | lyme borreliosis (lb) is caused by a group of pathogenic spirochetes - most often borrelia burgdorferi, b. afzelii, and b. garinii - that are vectored by hard ticks in the ixodes ricinus-persulcatus complex, which feed on a variety of mammals, birds, and lizards. although lb is one of the best-studied vector-borne zoonoses, the annual incidence in north america and europe leads other vector-borne diseases and continues to increase. what factors make the lb system so successful, and how can resea ... | 2009 | 19368764 |
| analysis of the rickettsia africae genome reveals that virulence acquisition in rickettsia species may be explained by genome reduction. | the rickettsia genus includes 25 validated species, 17 of which are proven human pathogens. among these, the pathogenicity varies greatly, from the highly virulent r. prowazekii, which causes epidemic typhus and kills its arthropod host, to the mild pathogen r. africae, the agent of african tick-bite fever, which does not affect the fitness of its tick vector. | 2009 | 19379498 |
| limited transcriptional responses of rickettsia rickettsii exposed to environmental stimuli. | rickettsiae are strict obligate intracellular pathogens that alternate between arthropod and mammalian hosts in a zoonotic cycle. typically, pathogenic bacteria that cycle between environmental sources and mammalian hosts adapt to the respective environments by coordinately regulating gene expression such that genes essential for survival and virulence are expressed only upon infection of mammals. temperature is a common environmental signal for upregulation of virulence gene expression although ... | 2009 | 19440298 |
| generation of antigenic variants via gene conversion: evidence for recombination fitness selection at the locus level in anaplasma marginale. | multiple bacterial and protozoal pathogens utilize gene conversion to generate antigenically variant surface proteins to evade immune clearance and establish persistent infection. both the donor alleles that encode the variants following recombination into an expression site and the donor loci themselves are under evolutionary selection: the alleles that encode variants that are sufficiently antigenically unique yet retain growth fitness and the loci that allow efficient recombination. we examin ... | 2009 | 19487473 |
| the immunomodulatory action of sialostatin l on dendritic cells reveals its potential to interfere with autoimmunity. | sialostatin l (sialol) is a secreted cysteine protease inhibitor identified in the salivary glands of the lyme disease vector ixodes scapularis. in this study, we reveal the mechanisms of sialol immunomodulatory actions on the vertebrate host. lps-induced maturation of dendritic cells from c57bl/6 mice was significantly reduced in the presence of sialol. although ova degradation was not affected by the presence of sialol in dendritic cell cultures, cathepsin s activity was partially inhibited, l ... | 2009 | 19494265 |
| genetic variation in the 16s mitochondrial dna gene of two canadian populations of dermacentor andersoni (acari: ixodidae). | the rocky mountain wood tick, dermacentor andersoni stiles, 1908, is of medical and veterinary importance because it can transmit pathogenic agents to humans, domestic livestock, and wildlife. the preferred attachment sites of d. andersoni adults and their ability to induce paralysis in hosts vary among populations, which may have a genetic basis. in this study, polymerase chain reaction (pcr)-single-strand conformation polymorphism (sscp) analyses and dna sequencing were used to determine the g ... | 2009 | 19496416 |
| transovarial transmission of francisella-like endosymbionts and anaplasma phagocytophilum variants in dermacentor albipictus (acari: ixodidae). | dermacentor albipictus (packard) is a north american tick that feeds on cervids and livestock. it is a suspected vector of anaplasmosis in cattle, but its microbial flora and vector potential remain underevaluated. we screened d. albipictus ticks collected from minnesota white-tailed deer (odocoileus virginianus) for bacteria of the genera anaplasma, ehrlichia, francisella, and rickettsia using polymerase chain reaction (pcr) gene amplification and sequence analyses. we detected anaplasma phagoc ... | 2009 | 19496436 |
| microarray analysis of gene expression changes in feeding female and male lone star ticks, amblyomma americanum (l). | a collection of est clones from female tick amblyomma americanum salivary glands was hybridized to rna from different feeding stages of female tick salivary glands and from unfed or feeding adult male ticks. in the female ticks, the expression patterns changed dramatically upon starting feeding, then changed again towards the end of feeding. on beginning feeding, genes possibly involved in survival on the host increased in expression as did many housekeeping genes. as feeding progressed, some of ... | 2009 | 19514082 |
| status of the "east side hypothesis" (transovarial interference) 25 years later. | rocky mountain spotted fever (rmsf) cases in the notorious bitterroot valley outbreak of the early 20th century were peculiarly distributed, with virtually all reported from the west side of the valley. such a distribution remained unexplained until burgdorfer and colleagues (1981) reported that endosymbiotic rickettsiae were prevalent in wood ticks on the east side of the bitterroot river valley but not on the west side. the "east side agent" was said to prevent the transovarial transmission of ... | 2009 | 19538274 |
| silencing of genes involved in anaplasma marginale-tick interactions affects the pathogen developmental cycle in dermacentor variabilis. | the cattle pathogen, anaplasma marginale, undergoes a developmental cycle in ticks that begins in gut cells. transmission to cattle occurs from salivary glands during a second tick feeding. at each site of development two forms of a. marginale (reticulated and dense) occur within a parasitophorous vacuole in the host cell cytoplasm. however, the role of tick genes in pathogen development is unknown. four genes, found in previous studies to be differentially expressed in dermacentor variabilis ti ... | 2009 | 19607704 |
| metapopulation structure for perpetuation of francisella tularensis tularensis. | outbreaks of type a tularemia due to francisella tularensis tularensis are typically sporadic and unstable, greatly hindering identification of the determinants of perpetuation and human risk. martha's vineyard, massachusetts has experienced an outbreak of type a tularemia which has persisted for 9 years. this unique situation has allowed us to conduct long-term eco-epidemiologic studies there. our hypothesis is that the agent of type a tularemia is perpetuated as a metapopulation, with many sma ... | 2009 | 19627585 |
| ehrlichia chaffeensis infections in drosophila melanogaster. | ehrlichia chaffeensis is an obligate, intracellular bacterium, transmitted by the tick amblyomma americanum, and is the causative agent of human monocytic ehrlichiosis infections. we previously demonstrated that e. chaffeensis is capable of growing in drosophila s2 cells. therefore, we tested the hypothesis that e. chaffeensis can infect adult drosophila melanogaster. adult drosophila organisms were experimentally challenged with intra-abdominal injections of bacteria. ehrlichia-infected flies s ... | 2009 | 19687202 |
| the role of saliva in tick feeding. | when attempting to feed on their hosts, ticks face the problem of host hemostasis (the vertebrate mechanisms that prevent blood loss), inflammation (that can produce itching or pain and thus initiate defensive behavior on their hosts) and adaptive immunity (by way of both cellular and humoral responses). against these barriers, ticks evolved a complex and sophisticated pharmacological armamentarium, consisting of bioactive lipids and proteins, to assist blood feeding. recent progress in transcri ... | 2009 | 19273185 |
| tularemia, plague, yersiniosis, and tyzzer's disease in wild rodents and lagomorphs in canada: a review. | information related to infection of wild rodents or lagomorphs in canada by francisella tularensis, yersinia pestis, other yersinia spp., and clostridium piliforme was searched for this study. reports on tularemia in humans linked to these species came from diagnostic databases, literature, wildlife health specialists, and public health agencies. tularemia has been diagnosed in 8 species of wild rodent and 2 species in the genus lepus in canada. tularemia occurred in wild animals, or in humans a ... | 2009 | 20190973 |
| genome sequence of the endosymbiont rickettsia peacockii and comparison with virulent rickettsia rickettsii: identification of virulence factors. | rickettsia peacockii, also known as the east side agent, is a non-pathogenic obligate intracellular bacterium found as an endosymbiont in dermacentor andersoni ticks in the western usa and canada. its presence in ticks is correlated with reduced prevalence of rickettsia rickettsii, the agent of rocky mountain spotted fever. it has been proposed that a virulent sfg rickettsia underwent changes to become the east side agent. we determined the genome sequence of r. peacockii and provide a compariso ... | 2009 | 20027221 |
| inducing active and passive immunity in sheep to paralysis caused by dermacentor andersoni. | arcott sheep were evaluated as a model for studying active and passive immunity to tick paralysis caused by dermacentor andersoni (stiles). the incidence of tick paralysis in sheep increased from 0 at doses < or = 0.33 ticks per kg to 100% at > or = 0.8 ticks per kg. the dose required for 50% paralysis was 0.42 ticks per kg. expressing dose as a ratio of initial ticks per unit body weight removed differences in response due to sheep weight. the interval from infestation to paralysis decreased fr ... | 2009 | 19960693 |
| infection of the endothelium by members of the order rickettsiales. | the vascular endothelium is the main target of a limited number of infectious agents, rickettsia, ehrlichia ruminantium, and orientia tsutsugamushi are among them. these arthropod-transmitted obligately-intracellular bacteria cause serious systemic diseases that are not infrequently lethal. in this review, we discuss the bacterial biology, vector biology, and clinical aspects of these conditions with particular emphasis on the interactions of these bacteria with the vascular endothelium and how ... | 2009 | 19967137 |
| transmission cycles of borrelia burgdorferi and b. bissettii in relation to habitat type in northwestern california. | this study was undertaken to determine which rodent species serve as primary reservoirs for the lyme disease spirochete borrelia burgdorferi in commonly occurring woodland types in inland areas of northwestern california, and to examine whether chaparral or grassland serve as source habitats for dispersal of b. burgdorferi- or b. bissettii-infected rodents into adjacent woodlands. the western gray squirrel (sciurus griseus) was commonly infected with b. burgdorferi in oak woodlands, whereas exam ... | 2009 | 20514140 |
| host surveys, ixodid tick biology and transmission scenarios as related to the tick-borne pathogen, ehrlichia canis. | the ehrlichioses have been subject to increasing interest from veterinary and public health perspectives, but experimental studies of these diseases and their etiologic agents can be challenging. ehrlichia canis, the primary etiologic agent of canine monocytic ehrlichiosis, is relatively well characterized and offers unique advantages and opportunities to study interactions between a monocytotropic pathogen and both its vertebrate and invertebrate hosts. historically, advances in tick-borne dise ... | 2008 | 18963493 |
| exploring the mialome of ticks: an annotated catalogue of midgut transcripts from the hard tick, dermacentor variabilis (acari: ixodidae). | ticks are obligate blood feeders. the midgut is the first major region of the body where blood and microbes ingested with the blood meal come in contact with the tick's internal tissues. little is known about protein expression in the digestive tract of ticks. in this study, for analysis of global gene expression during tick attachment and feeding, we generated and sequenced 1,679 random transcripts (ests) from cdna libraries from the midguts of female ticks at varying stages of feeding. | 2008 | 19021911 |
| effects of ambient temperature and cattle skin temperature on engorgement of dermacentor andersoni. | experiments were conducted to determine whether changes in skin temperature of cattle held at ambient temperatures ranging from 10 degrees c to 30 degrees c influenced engorgement of female dermacentor andersoni (stiles). average skin temperature of angus cattle increased from 29 degrees c to 34 degrees c, whereas skin temperature of holstein cattle increased from 32 degrees c to 35 degrees c over the range of ambient temperatures. changes in skin and ambient temperature strongly influenced the ... | 2008 | 19058622 |
| reproductive compatibility of prairie and montane populations of dermacentor andersoni. | genetic analysis of prairie and montane populations of dermacentor andersoni (stiles) originating from alberta (ab) and british columbia (bc), canada, respectively, indicated limited gene flow (nm <1) and a large amount of genetic differentiation (fst = 0.49) between the populations. the prairie population also had a greater level of genetic diversity. mating experiments indicated that females of geographically heterogeneous crosses had similar engorgement and oviposition failure as homogenous c ... | 2008 | 19058630 |
| field collection and genetic classification of tick-borne rickettsiae and rickettsiae-like pathogens from south texas: coxiella burnetii isolated from field-collected amblyomma cajennense. | we are reporting the first known isolation of the q-fever agent coxiella burnetii from field-collected cayenne ticks amblyomma cajennense in north america. q-fever affects a number of domestic ungulates where it can lead to abortion in sheep and goats. there is far less known about the disease's effects on wild species, primarily because of the tendency of the disease to self resolve and to provide long-term immunity to subsequent infections. the first recovery of c. burnetii in north america wa ... | 2008 | 19120212 |
| identification of genetic determinants of a tick-borne flavivirus associated with host-specific adaptation and pathogenicity. | tick-borne flaviviruses are maintained in nature in an enzootic cycle involving a tick vector and a vertebrate host. thus, the virus replicates in two disparate hosts, each providing selective pressures that can influence virus replication and pathogenicity. to identify viral determinants associated with replication in the individual hosts, plaque purified langat virus (tp21pp) was adapted to growth in mouse or tick cell lines to generate two virus variants, mnbp20 and isep20, respectively. viru ... | 2008 | 18823640 |
| rickettsia phylogenomics: unwinding the intricacies of obligate intracellular life. | completed genome sequences are rapidly increasing for rickettsia, obligate intracellular alpha-proteobacteria responsible for various human diseases, including epidemic typhus and rocky mountain spotted fever. in light of phylogeny, the establishment of orthologous groups (ogs) of open reading frames (orfs) will distinguish the core rickettsial genes and other group specific genes (class 1 ogs or c1ogs) from those distributed indiscriminately throughout the rickettsial tree (class 2 og or c2ogs) ... | 2008 | 19194535 |
| an insight into the sialome of the soft tick, ornithodorus parkeri. | while hard ticks (ixodidae) take several days to feed on their hosts, soft ticks (argasidae) feed faster, usually taking less than 1h per meal. saliva assists in the feeding process by providing a cocktail of anti-hemostatic, anti-inflammatory and immunomodullatory compounds. saliva of hard ticks has been shown to contain several families of genes each having multiple members, while those of soft ticks are relatively unexplored. analysis of the salivary transcriptome of the soft tick ornithodoru ... | 2008 | 18070662 |
| comparative sialomics between hard and soft ticks: implications for the evolution of blood-feeding behavior. | ticks evolved various mechanisms to modulate their host's hemostatic and immune defenses. differences in the anti-hemostatic repertoires suggest that hard and soft ticks evolved anti-hemostatic mechanisms independently, but raise questions on the conservation of salivary gland proteins in the ancestral tick lineage. to address this issue, the sialome (salivary gland secretory proteome) from the soft tick, argas monolakensis, was determined by proteomic analysis and cdna library construction of s ... | 2008 | 18070664 |
| variability and action mechanism of a family of anticomplement proteins in ixodes ricinus. | ticks are blood feeding arachnids that characteristically take a long blood meal. they must therefore counteract host defence mechanisms such as hemostasis, inflammation and the immune response. this is achieved by expressing batteries of salivary proteins coded by multigene families. | 2008 | 18167559 |
| superinfection as a driver of genomic diversification in antigenically variant pathogens. | a new pathogen strain can penetrate an immune host population only if it can escape immunity generated against the original strain. this model is best understood with influenza viruses, in which genetic drift creates antigenically distinct strains that can spread through host populations despite the presence of immunity against previous strains. whether this selection model for new strains applies to complex pathogens responsible for endemic persistent infections, such as anaplasmosis, relapsing ... | 2008 | 18252822 |
| comparison of the efficiency of biological transmission of anaplasma marginale (rickettsiales: anaplasmataceae) by dermacentor andersoni stiles (acari: ixodidae) with mechanical transmission by the horse fly, tabanus fuscicostatus hine (diptera: muscidae). | mechanical transmission ofanaplasma marginale by horse flies (tabanidae) is thought to be epidemiologically significant in some areas of the united states. we compared the relative efficiencies of mechanical transmission of anaplasma marginale by the horse fly, tabanus fuscicostatus hine, during acute infection (approximately 10(7) to approximately 10(9) infected erythrocytes [ie]/ml blood) with biological transmission by dermacentor andersoni stiles in the persistent phase of infection (approxi ... | 2008 | 18283950 |
| characterization and growth of polymorphic rickettsia felis in a tick cell line. | morphological differentiation in some arthropod-borne bacteria is correlated with increased bacterial virulence, transmission potential, and/or as a response to environmental stress. in the current study, we utilized an in vitro model to examine rickettsia felis morphology and growth under various culture conditions and bacterial densities to identify potential factors that contribute to polymorphism in rickettsiae. we utilized microscopy (electron microscopy and immunofluorescence), genomic (pc ... | 2008 | 18359823 |
| a possible canine tick-bite reaction to ixodes muris. | an airedale terrier became acutely ill following attachment of an ixodes muris tick. clinical signs waned within hours of tick removal, similar to a pattern previously documented in animals harboring i. muris. this supports the theory that i. muris can induce a noninfectious, severe inflammatory reaction in domestic animals. | 2008 | 18390101 |
| identification of rickettsia felis in the salivary glands of cat fleas. | rickettsia felis, a flea-associated rickettsial pathogen, has been identified in many tissues, including the digestive and reproductive tissues, within the cat flea, ctenocephalides felis. we utilized transmission electron microscopy and polymerase chain reaction to identify r. felis in the salivary glands of fed fleas and further define the distribution of r. felis within the arthropod host. we identified rickettsia-like organisms in salivary glands using electron microscopy. sequence analysis ... | 2008 | 18399779 |
| cellular and molecular characterization of an embryonic cell line (bme26) from the tick rhipicephalus (boophilus) microplus. | the cellular and molecular characteristics of a cell line (bme26) derived from embryos of the cattle tick rhipicephalus (boophilus) microplus were studied. the cells contained glycogen inclusions, numerous mitochondria, and vesicles with heterogeneous electron densities dispersed throughout the cytoplasm. vesicles contained lipids and sequestered palladium meso-porphyrin (pd-mp) and rhodamine-hemoglobin, suggesting their involvement in the autophagic and endocytic pathways. the cells phagocytose ... | 2008 | 18405834 |
| insight into the sialome of the castor bean tick, ixodes ricinus. | in recent years, there have been several sialome projects revealing transcripts expressed in the salivary glands of ticks, which are important vectors of several human diseases. here, we focused on the sialome of the european vector of lyme disease, ixodes ricinus. | 2008 | 18489795 |
| detection and identification of spotted fever group rickettsiae in dermacentor species from southern california. | dermacentor occidentalis marx and dermacentor variabilis (say) commonly bite humans in california. these dermacentor species may play a role in transmitting spotted fever group (sfg) rickettsiae to humans in many parts of the state where dermacentor andersoni stiles, a known vector for the etiologic agent of rocky mountain spotted fever, rickettsia rickettsii, is absent. however, the specific rickettsial agents present in these ticks and their current prevalence are poorly understood. in total, ... | 2008 | 18533446 |
| tick-borne transmission of two genetically distinct anaplasma marginale strains following superinfection of the mammalian reservoir host. | strain superinfection affects the dynamics of epidemiological spread of pathogens through a host population. superinfection has recently been shown to occur for two genetically distinct strains of the tick-borne pathogen anaplasma marginale that encode distinctly different surface protein variants. superinfected animals could serve as a reservoir for onward transmission of both strains if the tick vector is capable of acquiring and transmitting both strains. whether competition among strains dur ... | 2008 | 18573892 |
| transmission of bartonella henselae by ixodes ricinus. | bartonella spp. are facultative intracellular bacteria associated with several emerging diseases in humans and animals. b. henselae causes cat-scratch disease and is increasingly associated with several other syndromes, particularly ocular infections and endocarditis. cats are the main reservoir for b. henselae and the bacteria are transmitted to cats by cat fleas. however, new potential vectors are suspected of transmitting b. henselae, in particular, ixodes ricinus, the most abundant ixodid ti ... | 2008 | 18598628 |
| ricka expression is not sufficient to promote actin-based motility of rickettsia raoultii. | rickettsia raoultii is a novel rickettsia species recently isolated from dermacentor ticks and classified within the spotted fever group (sfg). the inability of r. raoultii to spread within l929 cells suggests that this bacterium is unable to polymerize host cell actin, a property exhibited by all sfg rickettsiae except r. peacocki. this result led us to investigate if ricka, the protein thought to generate actin nucleation, was expressed within this rickettsia species. | 2008 | 18612416 |
| north american encephalitic arboviruses. | arboviruses continue to be a major cause of encephalitis in north america, and west nile virus neuroinvasive disease is now the dominant cause of encephalitis. transmission to humans of north american arboviruses occurs by infected mosquitoes or ticks. most infections are asymptomatic or produce a flulike illness. rapid serum or cerebrospinal fluid igm antibody capture elisa assays are available to diagnosis the acute infection for all north american arboviruses. unfortunately, no antiviral drug ... | 2008 | 18657724 |
| indicators for elevated risk of human exposure to host-seeking adults of the rocky mountain wood tick (dermacentor andersoni) in colorado. | the human-biting adult stage of the rocky mountain wood tick (dermacentor andersoni) can cause tick paralysis in humans and domestic animals and is the primary tick vector in the intermountain west of the pathogens causing colorado tick fever, rocky mountain spotted fever, and tularemia. we conducted drag sampling studies in poudre canyon and rocky mountain national park of larimer county, co, to determine microhabitat use patterns by host-seeking d. andersoni adults and find environmental facto ... | 2008 | 18697314 |
| transgene expression and silencing in a tick cell line: a model system for functional tick genomics. | the genome project of the black legged tick, ixodes scapularis, provides sequence data for testing gene function and regulation in this important pathogen vector. we tested sleeping beauty (sb), a tc1/mariner group transposable element, and cationic lipid-based transfection reagents for delivery and genomic integration of transgenes into i. scapularis cell line ise6. plasmid dna and dsrna were effectively transfected into ise6 cells and they were successfully transformed to express a red fluores ... | 2008 | 18722527 |
| an insight into the salivary transcriptome and proteome of the soft tick and vector of epizootic bovine abortion, ornithodoros coriaceus. | the salivary glands of blood-sucking arthropods contain a redundant 'magic potion' that counteracts their vertebrate host's hemostasis, inflammation, and immunity. we here describe the salivary transcriptome and proteomics (sialome) of the soft tick ornithodoros coriaceus. the resulting analysis helps to consolidate the classification of common proteins found in both soft and hard ticks, such as the lipocalins, kunitz, cystatin, basic tail, hebraein, defensin, til domain, metalloprotease, 5'-nuc ... | 2008 | 18725333 |
| detection of francisella tularensis in ticks and identification of their genotypes using multiple-locus variable-number tandem repeat analysis. | tularemia was reported in china over 50 years ago, however, many epidemical characteristics remain unclear. in the present study, the prevalence of francisella tularensis in ticks was investigated during an epidemiological surveillance in china and then we measured their genetic diversity by conducting multiple-locus variable- number tandem repeat analysis (mlva). | 2008 | 18798995 |
| identification of midgut and salivary glands as specific and distinct barriers to efficient tick-borne transmission of anaplasma marginale. | understanding the determinants of efficient tick-borne microbial transmission is needed to better predict the emergence of highly transmissible pathogen strains and disease outbreaks. although the basic developmental cycle of anaplasma and ehrlichia spp. within the tick has been delineated, there are marked differences in the ability of specific strains to be efficiently tick transmitted. using the highly transmissible st. maries strain of anaplasma marginale in dermacentor andersoni as a positi ... | 2007 | 17420231 |
| experimental transmission of anaplasma marginale by male dermacentor reticulatus. | bovine anaplasmosis has been reported in several european countries, but the vector competency of tick species for anaplasma marginale from these localities has not been determined. because of the wide distributional range of dermacentor reticulatus within europe and the major role of dermacentor spp. as a vector of a. marginale in the united states, we tested the vector competency of d. reticulatus for a. marginale. | 2007 | 18053123 |
| infection of ixodes scapularis ticks with rickettsia monacensis expressing green fluorescent protein: a model system. | ticks (acari: ixodidae) are ubiquitous hosts of rickettsiae (rickettsiaceae: rickettsia), obligate intracellular bacteria that occur as a continuum from nonpathogenic arthropod endosymbionts to virulent pathogens of both arthropod vectors and vertebrates. visualization of rickettsiae in hosts has traditionally been limited to techniques utilizing fixed tissues. we report epifluorescence microscopy observations of unfixed tick tissues infected with a spotted fever group endosymbiont, rickettsia m ... | 2007 | 17125789 |
| isolation of rickettsia rhipicephali and rickettsia bellii from haemaphysalis juxtakochi ticks in the state of são paulo, brazil. | in the present study, attempts to isolate rickettsia in cell culture were performed individually in seven specimens of haemaphysalis juxtakochi ticks collected in the state of são paulo (southeastern brazil). rickettsia was successfully isolated by the shell vial technique and established in vero cell culture from six ticks (six isolates). dna extracted from infected cells of these isolates was tested by pcr and dna sequencing, using genus-specific rickettsia primers targeting the genes glta, ht ... | 2007 | 17142361 |
| transcriptome analysis of the salivary glands of dermacentor andersoni stiles (acari: ixodidae). | amongst blood-feeding arthropods, ticks of the family ixodidae (hard ticks) are vectors and reservoirs of a greater variety of infectious agents than any other ectoparasite. salivary glands of ixodid ticks secrete a large number of pharmacologically active molecules that not only facilitate feeding but also promote establishment of infectious agents. genomic, proteomic and immunologic characterization of bioactive salivary gland molecules are, therefore, important as they offer new insights into ... | 2007 | 17175446 |
| selection for simple major surface protein 2 variants during anaplasma marginale transmission to immunologically naïve animals. | anaplasma marginale, a rickettsial pathogen, evades clearance in the animal host by antigenic variation. under immune selection, a. marginale expresses complex major surface protein 2 mosaics, derived from multiple donor sequences. however, these mosaics have a selective advantage only in the presence of adaptive immunity and are rapidly replaced by simple variants following transmission. | 2007 | 17178787 |
| seasonal pattern of host-seeking activity by the human-biting adult life stage of dermacentor andersoni (acari: ixodidae). | nonremoval drag sampling was conducted in multiple sites in larimer county, co, from march to july 2006 to determine the seasonal pattern of host-seeking activity by the human-biting adult life stage of the rocky mountain wood tick, dermacentor andersoni stiles (acari: ixodidae). four sites, at elevations ranging from 1,790 to 2,470 m, consistently yielded host-seeking ticks. ticks were active from march until late june; the length of the active period ranged from 84 to 104 d. based on site-spec ... | 2007 | 17427709 |
| rickettsia peacockii, an endosymbiont of dermacentor andersoni, does not elicit or inhibit humoral immune responses from immunocompetent d. andersoni or ixodes scapularis cell lines. | ixodes scapularis and dermacentor andersoni cell lines were stimulated with heat-killed escherichia coli and micrococcus luteus to investigate whether infection by rickettsia peacockii, an endosymbiont of d. andersoni, modifies humoral immune responses. radial diffusion assays, western blotting, flow cytometry, and quantitative reverse-transcription pcr were used to determine if expression of bacteriolytic peptides, including lysozyme and defensin, was upregulated by bacterial stimulation or inf ... | 2007 | 17428539 |
| antibiotic treatment of the tick vector amblyomma americanum reduced reproductive fitness. | the lone star tick amblyomma americanum is a common pest and vector of infectious diseases for humans and other mammals in the southern and eastern united states. a coxiella sp. bacterial endosymbiont was highly prevalent in both laboratory-reared and field-collected a. americanum. the coxiella sp. was demonstrated in all stages of tick and in greatest densities in nymphs and adult females, while a rickettsia sp. was less prevalent and in lower densities when present. | 2007 | 17476327 |
| tick-borne flavivirus infection in ixodes scapularis larvae: development of a novel method for synchronous viral infection of ticks. | following a bite from an infected tick, tick-borne flaviviruses cause encephalitis, meningitis and hemorrhagic fever in humans. although these viruses spend most of their time in the tick, little is known regarding the virus-vector interactions. we developed a simple method for synchronously infecting ixodes scapularis larvae with langat virus (lgtv) by immersion in media containing the virus. this technique resulted in approximately 96% of ticks becoming infected. lgtv infection and replication ... | 2007 | 17490700 |
| immunity against ixodes scapularis salivary proteins expressed within 24 hours of attachment thwarts tick feeding and impairs borrelia transmission. | in north america, the black-legged tick, ixodes scapularis, an obligate haematophagus arthropod, is a vector of several human pathogens including borrelia burgdorferi, the lyme disease agent. in this report, we show that the tick salivary gland transcriptome and proteome is dynamic and changes during the process of engorgement. we demonstrate, using a guinea pig model of i. scapularis feeding and b. burgdorferi transmission, that immunity directed against salivary proteins expressed in the first ... | 2007 | 17505544 |
| differentiation of three species of ixodid tick, dermacentor andersoni, d. variabilis and d. albipictus, by pcr-based approaches using markers in ribosomal dna. | three species of dermacentor, dermacentor albipictus, dermacentor andersoni and dermacentor variabilis, commonly occur in canada. d. andersoni and d. variabilis are morphologically similar and are important vectors of human and animal pathogens. a practical polymerase chain reaction (pcr) assay, based on the amplification of part of the second internal transcribed spacer ribosomal dna (pits-2 rdna), was developed to distinguish d. andersoni from d. variabilis. in addition, single-strand conforma ... | 2007 | 17544620 |
| conservation of transmission phenotype of anaplasma marginale (rickettsiales: anaplasmataceae) strains among dermacentor and rhipicephalus ticks (acari: ixodidae). | before the eradication of boophilus ticks from the united states, rhipicephalus (boophilus) microplus (canestrini) and rhipicephalus (boophilus) annulatus (say) were important biological vectors of the cattle pathogen anaplasma marginale theiler. in the absence of boophilus ticks, a. marginale continues to be transmitted by dermacentor ticks. however, a few u.s. strains are not transmissible by dermacentor andersoni stiles, dermacentor variabilis (say), or both, raising the question of how these ... | 2007 | 17547235 |
| gulf coast ticks (amblyomma maculatum) and rickettsia parkeri, united states. | geographic distribution of rickettsia parkeri in its us tick vector, amblyomma maculatum, was evaluated by pcr. r. parkeri was detected in ticks from florida, georgia, kentucky, mississippi, oklahoma, and south carolina, which suggests that a. maculatum may be responsible for additional cases of r. parkeri rickettsiosis throughout much of its us range. | 2007 | 17553257 |
| molecular typing of isolates of rickettsia rickettsii by use of dna sequencing of variable intergenic regions. | rickettsia rickettsii, the causative agent of rocky mountain spotted fever, is found throughout the americas, where it is associated with different animal reservoirs and tick vectors. no molecular typing system currently exists to allow for the robust differentiation of isolates of r. rickettsii. analysis of eight completed genome sequences of rickettsial species revealed a high degree of sequence conservation within the coding regions of chromosomes in the genus. intergenic regions between codi ... | 2007 | 17553977 |
| q fever (coxiella burnetii) among man and farm animals in north sinai, egypt. | antibodies against coxiella burnetii were estimated among sheep, goats and camels (190), their owners (150 patients with pyrexia of unknown origin) and 30 normal individuals in north sinai over the 2006 by indirect immounofluorescence assay. nested polymerase chain reaction was used to detect com-1 gene (genetic target of c. burnetii) encoding a 27-kda outer membrane protein in the samples. c. burnetii ifa antibodies (igm & igg) in patients were 8 (5.3%) and a healthy control (3.3%). the overall ... | 2007 | 17580573 |
| abnormal morphology of an adult rocky mountain wood tick, dermacentor andersoni (acari: ixodidae). | during a collection of ticks from vegetation in march 2006, a single adult male rocky mountain wood tick, dermacentor andersoni (stiles, 1908), was collected that exhibited unique morphological anomalies, including the absence of a leg on the right side of the body. coxa iv on the right side also was missing in this specimen. such teratological changes have not been reported previously for d. andersoni. | 2007 | 17626369 |
| identification of rickettsial isolates at the species level using multi-spacer typing. | in order to estimate whether multi-spacer typing (mst), based on the sequencing of variable intergenic spacers, could serve for the identification of rickettsia at the species level, we applied it to 108 rickettsial isolates or arthropod amplicons that include representatives of 23 valid rickettsia species. | 2007 | 17662158 |
| climate-based model predicting acarological risk of encountering the human-biting adult life stage of dermacentor andersoni (acari: ixodidae) in a key habitat type in colorado. | we exploited an elevation (climate) gradient ranging from 1,700 to 2,500 m in poudre canyon of larimer county, co, to determine climatic correlates of abundance per 15-s drag sampling time unit (hereafter referred to as abundance) of the human-biting adult life stage of the rocky mountain wood tick, dermacentor andersoni stiles (acari: ixodidae), in a key risk habitat for tick exposure: south/west-facing, rocky hillsides with mixed grass-brush-conifer vegetation. the relationship between elevati ... | 2007 | 17695027 |
| localization and visualization of a coxiella-type symbiont within the lone star tick, amblyomma americanum. | a coxiella-type microbe occurs at 100% frequency in all amblyomma americanum ticks thus far tested. using laboratory-reared ticks free of other microbes, we identified the amblyomma-associated coxiella microbe in several types of tissue and at various stages of the life cycle of a. americanum by 16s rrna gene sequencing and diagnostic pcr. we visualized amblyomma-associated coxiella through the use of a diagnostic fluorescence in situ hybridization (fish) assay supplemented with pcr-based detect ... | 2007 | 17720830 |
| propagation of arthropod-borne rickettsia spp. in two mosquito cell lines. | rickettsiae are obligate intracellular alphaproteobacteria that include pathogenic species in the spotted fever, typhus, and transitional groups. the development of a standardized cell line in which diverse rickettsiae can be grown and compared would be highly advantageous to investigate the differences among and between pathogenic and nonpathogenic species of rickettsiae. although several rickettsial species have been grown in tick cells, tick cells are more difficult to maintain and they grow ... | 2007 | 17766452 |
| maintenance of antibody to pathogen epitopes generated by segmental gene conversion is highly dynamic during long-term persistent infection. | multiple bacterial and protozoal pathogens utilize gene conversion to generate rapid intrahost antigenic variation. both large- and small-genome pathogens expand the size of the variant pool via a combinatorial process in which oligonucleotide segments from distinct donor loci are recombined in various combinations into expression sites. although the potential combinatorial diversity generated by this segmental gene conversion mechanism is quite large, the functional variant pool depends on whet ... | 2007 | 17785476 |
| experimental transmission of bovine anaplasmosis (caused by anaplasma marginale) by means of dermacentor variabilis and d. andersoni (ixodidae) collected in western canada. | canadian cattle are free of bovine anaplasmosis, with the exception of 4 isolated incursions since 1968, which were eradicated. it is not known why the disease has not become established in regions of canada adjacent to the united states where it is endemic. to assess the vector competence of wild-caught ticks in cattle-rearing regions, dermacentor variabilis and d. andersoni were collected in western canada and fed on calves experimentally infected with anaplasma marginale (st. maries strain). ... | 2007 | 17955901 |
| phagocytosis of the lyme disease spirochete, borrelia burgdorferi, by cells from the ticks, ixodes scapularis and dermacentor andersoni, infected with an endosymbiont, rickettsia peacockii. | tick cell lines were used to model the effects of endosymbiont infection on phagocytic immune responses. the lines tested for their ability to phagocytose the lyme disease spirochete, borrelia burgdorferi (spirochaetales: spirochaetaceae), were ise6 and ide12 from the black-legged tick, ixodes scapularis say (acari: ixodidae) and dae15 from the rocky mountain wood tick, dermacentor andersoni stiles. rickettsia peacockii (rickettsiales: rickettsiaceae), an endosymbiont of d. andersoni, was used a ... | 2007 | 20331397 |
| coinfections acquired from ixodes ticks. | the pathogens that cause lyme disease (ld), human anaplasmosis, and babesiosis can coexist in ixodes ticks and cause human coinfections. although the risk of human coinfection differs by geographic location, the true prevalence of coinfecting pathogens among ixodes ticks remains largely unknown for the majority of geographic locations. the prevalence of dually infected ixodes ticks appears highest among ticks from regions of north america and europe where ld is endemic, with reported prevalences ... | 2006 | 17041141 |
| distribution, seasonality, and hosts of the rocky mountain wood tick in the united states. | anaplasma marginale theiler is a tick-borne pathogen that causes anaplasmosis in cattle. there are approximately 20 tick species worldwide that are implicated as vectors of this pathogen. in the united states, dermacentor andersoni stiles and dermacentor variabilis (say) are the principal vectors. the risk of transmission of anaplasmosis to cattle has been largely based on the distribution of d. andersoni in the united states. we developed a centralized geographic database that incorporates coll ... | 2006 | 16506443 |
| real-time pcr for francisella tularensis types a and b. | 2006 | 17283646 | |
| differential expression and sequence conservation of the anaplasma marginale msp2 gene superfamily outer membrane proteins. | bacterial pathogens in the genera anaplasma and ehrlichia encode a protein superfamily, pfam01617, which includes the predominant outer membrane proteins (omps) of each species, major surface protein 2 (msp2) and msp3 of anaplasma marginale and anaplasma ovis, anaplasma phagocytophilum msp2 (p44), ehrlichia chaffeensis p28-omp, ehrlichia canis p30, and ehrlichia ruminantium map1, and has been shown to be involved in both antigenic variation within the mammalian host and differential expression b ... | 2006 | 16714578 |
| analysis of the anaplasma marginale major surface protein 1 complex protein composition by tandem mass spectrometry. | the protective major surface protein 1 (msp1) complex of anaplasma marginale is a heteromer of msp1a and msp1b, encoded by a multigene family. the msp1beta sequences were highly conserved throughout infection. however, liquid chromatography-tandem mass spectrometry analysis identified only a single msp1b protein, msp1b1, within the msp1 complex. | 2006 | 16788207 |
| isolation and identification of rickettsia massiliae from rhipicephalus sanguineus ticks collected in arizona. | twenty rhipicephalus sanguineus ticks collected in eastern arizona were tested by pcr assay to establish their infection rate with spotted fever group rickettsiae. with a nested pcr assay which detects a fragment of the rickettsia genus-specific 17-kda antigen gene (htra), five ticks (25%) were found to contain rickettsial dna. one rickettsial isolate was obtained from these ticks by inoculating a suspension of a triturated tick into monolayers of vero e6 monkey kidney cells and xtc-2 clawed toa ... | 2006 | 16885311 |
| rickettsia felis from cat fleas: isolation and culture in a tick-derived cell line. | rickettsia felis, the etiologic agent of spotted fever, is maintained in cat fleas by vertical transmission and resembles other tick-borne spotted fever group rickettsiae. in the present study, we utilized an ixodes scapularis-derived tick cell line, ise6, to achieve isolation and propagation of r. felis. a cytopathic effect of increased vacuolization was commonly observed in r. felis-infected cells, while lysis of host cells was not evident despite large numbers of rickettsiae. electron microsc ... | 2006 | 16885313 |
| the emerging diversity of rickettsia. | the best-known members of the bacterial genus rickettsia are associates of blood-feeding arthropods that are pathogenic when transmitted to vertebrates. these species include the agents of acute human disease such as typhus and rocky mountain spotted fever. however, many other rickettsia have been uncovered in recent surveys of bacteria associated with arthropods and other invertebrates; the hosts of these bacteria have no relationship with vertebrates. it is therefore perhaps more appropriate t ... | 2006 | 16901827 |
| a canadian bison isolate of anaplasma marginale (rickettsiales: anaplasmataceae) is not transmissible by dermacentor andersoni (acari: ixodidae), whereas ticks from two canadian d. andersoni populations are competent vectors of a u.s. strain. | anaplasma marginale theiler is a tick-borne rickettsial pathogen of cattle with a global distribution in both temperate and tropical regions. the pathogen is endemic in regions within the united states, whereas the canadian cattle population is considered to be free ofa. marginale. farmed bison, bison bison l., in central saskatchewan have been found to be infected with a. marginale; however, there is no evidence of transmission from bison to cattle. we tested a saskatchewan bison isolate of a. ... | 2006 | 17017236 |
| molecular typing of novel rickettsia rickettsii isolates from arizona. | seven isolates of rickettsia rickettsii were obtained from a skin biopsy, two whole-blood specimens, and from rhipicephalus sanguineus ticks from eastern arizona. molecular typing of seven isolates of r. rickettsii and dna samples from two other rh. sanguineus ticks infected with r. rickettsii was conducted by pcr and dna sequencing of rompa and 12 variable-number tandem repeat regions (vntrs). all dna specimens from arizona were identical to each other and to reference human and dermacentor and ... | 2006 | 17114781 |
| gene expression in male tick salivary glands is affected by feeding in the presence of females. | in this study, we have compared gene expression in the salivary glands of male dermacentor andersoni ticks fed in the presence or absence of females to that in unfed males. we have established that the patterns of expression are different using arbitrarily primed polymerase chain reaction following reverse transcription of rna (rap-pcr) and differential display. our results indicate a significant difference in salivary gland gene expression between fed and unfed males and also between males fed ... | 2006 | 17103403 |
| sarcoptes scabiei (acari: sarcoptidae) mite extract modulates expression of cytokines and adhesion molecules by human dermal microvascular endothelial cells. | the inflammatory and immune responses seen with the worldwide disease scabies, caused by the mite sarcoptes scabiei (de geer) (acari: sarcoptidae), are complex. clinical symptoms are delayed for weeks in patients when they are infested with scabies for the first time. this study was undertaken to elucidate the role of the human dermal microvascular endothelial cell (hmvec-d) in modulating the inflammatory and immune responses in the skin to s. scabiei. extracts of s. scabiei were incubated with ... | 2006 | 17017228 |