Publications

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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
detection of "candidatus rickettsia sp. strain argentina"and rickettsia bellii in amblyomma ticks (acari: ixodidae) from northern argentina.	ixodid ticks were collected from vegetation and from humans, wild and domestic mammals in a rural area in the semi-arid argentine chaco in late spring 2006 to evaluate their potential role as vectors of spotted fever group (sfg) rickettsiae. a total of 233 adult ticks, identified as amblyomma parvum, amblyomma tigrinum and amblyomma pseudoconcolor, was examined for rickettsia spp. we identified an sfg rickettsia of unknown pathogenicity, "candidatus rickettsia sp. strain argentina", in a. parvum ...	2010	20186466
expression of heat shock and other stress response proteins in ticks and cultured tick cells in response to anaplasma spp. infection and heat shock.	ticks are ectoparasites of animals and humans that serve as vectors of anaplasma and other pathogens that affect humans and animals worldwide. ticks and the pathogens that they transmit have coevolved molecular interactions involving genetic traits of both the tick and the pathogen that mediate their development and survival. in this paper, the expression of heat shock proteins (hsps) and other stress response proteins (srps) was characterized in ticks and cultured tick cells by proteomics and t ...	2010	22084679
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
stability and tick transmission phenotype of gfp-transformed anaplasma marginale through a complete in vivo infection cycle.	we tested the stability and tick transmission phenotype of transformed anaplasma marginale through a complete in vivo infection cycle. similar to the wild type, the gfp-transformed a. marginale strain established infection in cattle, a natural reservoir host, and persisted in immune competent animals. the tick infection rates for the transformed a. marginale and the wild type were the same. however, there were significantly lower levels of the transformed a. marginale than of the wild type in th ...	2010	21057014
identification of anaplasma marginale outer membrane protein antigens conserved between a. marginale sensu stricto strains and the live a. marginale subsp. centrale vaccine.	live vaccination with anaplasma marginale subsp. centrale (synonym for anaplasma centrale) induces protection against severe disease upon challenge with a. marginale sensu stricto strains. despite over a century of field use, the targets of protective immunity remained unknown. using a broad proteomic approach, we identified the proteins in a challenge sensu stricto strain that were bound by the relevant antibody isotype induced by live vaccination with anaplasma marginale subsp. centrale. a cor ...	2010	21189322
the expression of genes coding for distinct types of glycine-rich proteins varies according to the biology of three metastriate ticks, rhipicephalus (boophilus) microplus, rhipicephalus sanguineus and amblyomma cajennense.	ticks secrete a cement cone composed of many salivary proteins, some of which are rich in the amino acid glycine in order to attach to their hosts' skin. glycine-rich proteins (grps) are a large family of heterogeneous proteins that have different functions and features; noteworthy are their adhesive and tensile characteristics. these properties may be essential for successful attachment of the metastriate ticks to the host and the prolonged feeding necessary for engorgement. in this work, we an ...	2010	20529354
a 60-year meta-analysis of tick paralysis in the united states: a predictable, preventable, and often misdiagnosed poisoning.	tick paralysis (tp) is a neurotoxic poisoning primarily afflicting young girls in endemic regions. recent case series of tp have described increasing misdiagnoses of tp as the guillain-barré syndrome (gbs). a meta-analysis of the scientific literature was conducted using internet search engines to assess the evolving epidemiology of tp. fifty well-documented cases of tp were analyzed over the period 1946-2006. cases were stratified by demographics, clinical manifestations, and outcomes. misdiagn ...	2010	20186584
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
rhipicephalus microplus salivary gland molecules induce differential cd86 expression in murine macrophages.	abstract:	2010	21054882
an insight into the sialotranscriptome of the brown dog tick, rhipicephalus sanguineus.	rhipicephalus sanguineus, known as the brown dog tick, is a common ectoparasite of domestic dogs and can be found worldwide. r.sanguineus is recognized as the primary vector of the etiological agent of canine monocytic ehrlichiosis and canine babesiosis. here we present the first description of a r. sanguineus salivary gland transcriptome by the production and analysis of 2,034 expressed sequence tags (est) from two cdna libraries, one consctructed using mrna from dissected salivary glands from ...	2010	20650005
analysis of rickettsia typhi-infected and uninfected cat flea (ctenocephalides felis) midgut cdna libraries: deciphering molecular pathways involved in host response to r. typhi infection.	murine typhus is a flea-borne febrile illness that is caused by the obligate intracellular bacterium, rickettsia typhi. the cat flea, ctenocephalides felis, acquires r. typhi by imbibing a bloodmeal from a rickettsemic vertebrate host. to explore which transcripts are expressed in the midgut in response to challenge with r. typhi, cdna libraries of r. typhi-infected and uninfected midguts of c. felis were constructed. in this study, we examined midgut transcript levels for select c. felis serine ...	2010	20017753
francisella acid phosphatases inactivate the nadph oxidase in human phagocytes.	francisella tularensis contains four putative acid phosphatases that are conserved in francisella novicida. an f. novicida quadruple mutant (acpa, acpb, acpc, and hap [deltaabch]) is unable to escape the phagosome or survive in macrophages and is attenuated in the mouse model. we explored whether reduced survival of the deltaabch mutant within phagocytes is related to the oxidative response by human neutrophils and macrophages. f. novicida and f. tularensis subspecies failed to stimulate reactiv ...	2010	20348422
bartonella spp. transmission by ticks not established.	bartonella spp. infect humans and many animal species. mainly because pcr studies have demonstrated bartonella dna in ticks, some healthcare providers believe that these microorganisms are transmitted by ticks. b. henselae, in particular, is regarded as being present in and transmissible by the ixodes scapularis tick. the presence of a microbial agent within a tick, however, does not imply that the tick might transmit it during the course of blood feeding and does not confer epidemiologic import ...	2010	20202410
isolation of rickettsia parkeri and identification of a novel spotted fever group rickettsia sp. from gulf coast ticks (amblyomma maculatum) in the united states.	until recently, amblyomma maculatum (the gulf coast tick) had garnered little attention compared to other species of human-biting ticks in the united states. a. maculatum is now recognized as the principal vector of rickettsia parkeri, a pathogenic spotted fever group rickettsia (sfgr) that causes an eschar-associated illness in humans that resembles rocky mountain spotted fever. a novel sfgr, distinct from other recognized rickettsia spp., has also been detected recently in a. maculatum specime ...	2010	20208020
association of pathogen strain-specific gene transcription and transmission efficiency phenotype of anaplasma marginale.	efficient transmission of pathogens by an arthropod vector is influenced by the ability of the pathogen to replicate and develop infectiousness within the arthropod host. while the basic life cycle of development within and transmission from the arthropod vector are known for many bacterial and protozoan pathogens, the determinants of transmission efficiency are largely unknown and represent a significant gap in our knowledge. the st. maries strain of anaplasma marginale is a high-transmission-e ...	2010	20308303
identification of anaplasma marginale proteins specifically upregulated during colonization of the tick vector.	the transition between infection of the mammalian host and colonization of an arthropod vector is required for the ongoing transmission of a broad array of pathogens, from viruses to protozoa. understanding how this transition is mediated provides opportunities to disrupt transmission through either chemotherapy or immunization. we used an unbiased proteomic screen to identify anaplasma marginale proteins specifically upregulated in the tick compared to the mammalian host. comparative mass spect ...	2010	20439479
wide dispersal and possible multiple origins of low-copy-number plasmids in rickettsia species associated with blood-feeding arthropods.	plasmids are mobile genetic elements of bacteria that can impart important adaptive traits, such as increased virulence or antibiotic resistance. we report the existence of plasmids in rickettsia (rickettsiales; rickettsiaceae) species, including rickettsia akari, "candidatus rickettsia amblyommii," r. bellii, r. rhipicephali, and reis, the rickettsial endosymbiont of ixodes scapularis. all of the rickettsiae were isolated from humans or north and south american ticks. r. parkeri isolates from b ...	2010	20097813
extraction of total nucleic acids from ticks for the detection of bacterial and viral pathogens.	ticks harbor numerous bacterial, protozoal, and viral pathogens that can cause serious infections in humans and domestic animals. active surveillance of the tick vector can provide insight into the frequency and distribution of important pathogens in the environment. nucleic-acid based detection of tick-borne bacterial, protozoan, and viral pathogens requires the extraction of both dna and rna (total nucleic acids) from ticks. traditional methods for nucleic acid extraction are limited to extrac ...	2010	20180313
tick paralysis caused by dermacentor andersoni (acari: ixodidae) is a heritable trait.	the heritability of the ability to cause paralysis was examined in crosses of virulent and avirulent dermacentor andersoni (stiles) (acari: ixodidae). virulence was assessed using hamster bioassay. paralysis was caused by the virulent parental strain but not by the avirulent parental strain. four crosses were made: avirulent female x avirulent male (aa cross), virulent female x virulent male (vv cross), avirulent female x virulent male (av cross), and virulent female x avirulent male (va cross). ...	2010	20380302
coxiella burnetii in humans and ticks in rural senegal.	q fever is a worldwide zoonotic disease caused by coxiella burnetii. epidemiologically, animals are considered reservoirs and humans incidental hosts.	2010	20386603
rickettsial ompb promoter regulated expression of gfpuv in transformed rickettsia montanensis.	rickettsia spp. (rickettsiales: rickettsiaceae) are gram-negative, obligate intracellular, alpha-proteobacteria that have historically been associated with blood-feeding arthropods. certain species cause typhus and spotted fevers in humans, but others are of uncertain pathogenicity or may be strict arthropod endosymbionts. genetic manipulation of rickettsiae should facilitate a better understanding of their interactions with hosts.	2010	20126457
detection of a new arsenophonus-type bacterium in canadian populations of the rocky mountain wood tick, dermacentor andersoni.	ticks of the genus dermacentor are important vectors of human and animal pathogens in north america. they also carry a variety of endosymbiotic (i.e. non-pathogenic) bacteria. the american dog tick, d. variabilis, is known to be infected with gammaproteobacteria of the genus arsenophonus. however, there have been no previous reports of arsenophonus-type bacteria in the rocky mountain wood tick, d. andersoni, a species that is sympatric with d. variabilis in the western parts of its distributiona ...	2010	20186465
persistence of buggy creek virus (togaviridae, alphavirus) for two years in unfed swallow bugs (hemiptera: cimicidae: oeciacus vicarius).	alphaviruses (togaviridae) have rarely been found to persist for long in the adult insects that serve as their vectors. the ectoparasitic swallow bug (hemiptera: cimicidae: oeciacus vicarius horvath), the vector for buggy creek virus (bcrv; togaviridae, alphavirus), lives year-round in the mud nests of its host, the cliff swallow (petrochelidon pyrrhonota vieillot). we measured the prevalence of bcrv in swallow bugs at sites with cliff swallows present and at the same sites after cliff swallows ...	2010	20496591
anaplasma marginale infection with persistent high-load bacteremia induces a dysfunctional memory cd4+ t lymphocyte response but sustained high igg titers.	control of blood-borne infections is dependent on antigen-specific effector and memory t cells and high-affinity igg responses. in chronic infections characterized by a high antigen load, it has been shown that antigen-specific t and b cells are vulnerable to downregulation and apoptosis. anaplasma marginale is a persistent infection of cattle characterized by acute and chronic high-load bacteremia. we previously showed that cd4(+) t cells primed by immunization with an a. marginale outer membra ...	2010	20943884
evaluation of rickettsia japonica pathogenesis and reservoir potential in dogs by experimental inoculation and epidemiologic survey.	rickettsia japonica pathogenesis and reservoir potential in dogs were evaluated by both experimental inoculation and epidemiologic survey. in the experimental inoculation study, dogs 1 and 2 were pretreated with an immunosuppressive dose of cyclosporine 14 days before inoculation and became ill after exposure to r. japonica. dogs exhibited clinical signs, including fever, anorexia, depression, and decreased water consumption, between 36 and 96 h after inoculation, but these signs disappeared spo ...	2010	20980481
an update on bovine anaplasmosis (anaplasma marginale) in canada.		2010	21037882
differences in prevalence of borrelia burgdorferi and anaplasma spp. infection among host-seeking dermacentor occidentalis, ixodes pacificus, and ornithodoros coriaceus ticks in northwestern california.	previous studies revealed that the pacific coast tick (dermacentor occidentalis) is infected occasionally with the agents of lyme disease (borrelia burgdorferi) or human granulocytic anaplasmosis (anaplasma phagocytophilum) and that it is an inefficient experimental vector of b. burgdorferi. the relationship of the pajahuello tick (ornithodoros coriaceus) to each of these bacterial zoonotic agents has not been reported. the primary bridging vector of both bacterial zoonotic agents to humans is t ...	2010	21359090
a further insight into the sialome of the tropical bont tick, amblyomma variegatum.	ticks--vectors of medical and veterinary importance--are themselves also significant pests. tick salivary proteins are the result of adaptation to blood feeding and contain inhibitors of blood clotting, platelet aggregation, and angiogenesis, as well as vasodilators and immunomodulators. a previous analysis of the sialotranscriptome (from the greek sialo, saliva) of amblyomma variegatum is revisited in light of recent advances in tick sialomes and provides a database to perform a proteomic study ...	2011	21362191
tick paralysis in australia caused by ixodes holocyclus neumann.	ticks are obligate haematophagous ectoparasites of various animals, including humans, and are abundant in temperate and tropical zones around the world. they are the most important vectors for the pathogens causing disease in livestock and second only to mosquitoes as vectors of pathogens causing human disease. ticks are formidable arachnids, capable of not only transmitting the pathogens involved in some infectious diseases but also of inducing allergies and causing toxicoses and paralysis, wit ...	2011	21396246
assessment of bacterial diversity in the cattle tick rhipicephalus (boophilus) microplus through tag-encoded pyrosequencing.	ticks are regarded as the most relevant vectors of disease-causing pathogens in domestic and wild animals. the cattle tick, rhipicephalus (boophilus) microplus, hinders livestock production in tropical and subtropical parts of the world where it is endemic. tick microbiomes remain largely unexplored. the objective of this study was to explore the r. microplus microbiome by applying the bacterial 16s tag-encoded flx-titanium amplicon pyrosequencing (btefap) technique to characterize its bacterial ...	2011	21211038
isolation of a rickettsial pathogen from a non-hematophagous arthropod.	rickettsial diversity is intriguing in that some species are transmissible to vertebrates, while others appear exclusive to invertebrate hosts. of particular interest is rickettsia felis, identifiable in both stored product insect pests and hematophagous disease vectors. to understand rickettsial survival tactics in, and probable movement between, both insect systems will explicate the determinants of rickettsial pathogenicity. towards this objective, a population of liposcelis bostrychophila, c ...	2011	21283549
complementation of rickettsia rickettsii rela/spot restores a nonlytic plaque phenotype.	spotted fever group rickettsiae are known to produce distinct plaque phenotypes. strains that cause lytic infections in cell culture form clear plaques, while nonlytic strains form opaque plaques in which the cells remain intact. clear plaques have historically been associated with more-virulent species or strains of spotted fever group rickettsiae. we have selected spontaneous mutant pairs from two independent strains of rickettsia rickettsii, the virulent r strain and the avirulent iowa strain ...	2011	21300770
novel genotypes of anaplasma bovis, "candidatus midichloria" sp. and ignatzschineria sp. in the rocky mountain wood tick, dermacentor andersoni.	bovine anaplasmosis, caused by anaplasma marginale, is a vector-borne disease that is enzootic in many parts of the usa. although dermacentor andersoni, a major vector of a. marginale, occurs in canada, the canadian cattle herds are currently considered free of bovine anaplasmosis. there have been two outbreaks of the disease in the province of saskatchewan, but these have been linked to the importation of infected animals. however, the distribution of bovine anaplasmosis may alter with range ex ...	2011	21334146
the immunopathology of canine vector-borne diseases.	abstract: the canine vector-borne infectious diseases (cvbds) are an emerging problem in veterinary medicine and the zoonotic potential of many of these agents is a significant consideration for human health. the successful diagnosis, treatment and prevention of these infections is dependent upon firm understanding of the underlying immunopathology of the diseases in which there are unique tripartite interactions between the microorganism, the vector and the host immune system. although signific ...	2011	21489234
one health: the importance of companion animal vector-borne diseases.	abstract: the international prominence accorded the 'one health' concept of co-ordinated activity of those involved in human and animal health is a modern incarnation of a long tradition of comparative medicine, with roots in the ancient civilizations and a golden era during the 19th century explosion of knowledge in the field of infectious disease research. modern one health tends to focus on zoonotic pathogens emerging from wildlife and production animal species, but one of the most significan ...	2011	21489237
francisella-arthropod vector interaction and its role in patho-adaptation to infect mammals.	francisella tularensis is a gram-negative, intracellular, zoonotic bacterium, and is the causative agent of tularemia with a broad host range. arthropods such as ticks, mosquitoes, and flies maintain f. tularensis in nature by transmitting the bacteria among small mammals. while the tick is largely believed to be a biological vector of f. tularensis, transmission by mosquitoes and flies is largely believed to be mechanical on the mouthpart through interrupted feedings. however, the mechanism of ...	2011	21687425
experimental infection of amblyomma aureolatum ticks with rickettsia rickettsii.	we experimentally infected amblyomma aureolatum ticks with the bacterium rickettsia rickettsii, the etiologic agent of rocky mountain spotted fever (rmsf). these ticks are a vector for rmsf in brazil. r. rickettsii was efficiently conserved by both transstadial maintenance and vertical (transovarial) transmission to 100% of the ticks through 4 laboratory generations. however, lower reproductive performance and survival of infected females was attributed to r. rickettsii infection. therefore, bec ...	2011	21529391
expression of anaplasma marginale ankyrin repeat-containing proteins during infection of the mammalian host and tick vector.	transmission of tick-borne pathogens requires transition between distinct host environments with infection and replication in host-specific cell types. anaplasma marginale illustrates this transition: in the mammalian host the bacteria infects and replicates in mature (non-nucleated) erythrocytes while in the tick vector replication occurs in nucleated epithelial cells. we hypothesized that proteins containing ankyrin motifs would be expressed by a. marginale only in tick cells and would traffic ...	2011	21576345
francisella tularensis molecular typing using differential insertion sequence amplification (disa).	tularemia is a potentially fatal disease that is caused by the highly infectious and zoonotic pathogen francisella tularensis. despite the monomorphic nature of sequenced f. tularensis genomes, there is a significant degree of plasticity in the organization of genetic elements. the observed variability in these genomes is primarily due to the transposition of direct repeats and insertion sequence (is) elements. since current methods used to genotype f. tularensis are time-consuming and require e ...	2011	21613430
eschar and neck lymphadenopathy caused by francisella tularensis after a tick bite: a case report.		2011	21418587