Publications

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development of anaplasma ovis (rickettsiales: anaplasmataceae) in male dermacentor andersoni (acari: ixodidae) transferred from infected to susceptible sheep.the development of anaplasma ovis was studied in dermacentor andersoni males transferred from infected to susceptible sheep. laboratory-reared male d. andersoni were allowed to feed for 6 d on a sheep with ascending a. ovis parasitemia. the ticks were removed and held at room temperature in a humidity chamber for 6 d, after which they were allowed to feed on five susceptible sheep for 1, 3, 5, 7, or 9 d. gut and salivary glands were collected from ticks during the 21-d experiment and examined wi ...19921552534
effects of tick infestation on the plaque-forming cell response to a thymic dependent antigen.strain-2 guinea-pigs were given two five-day infestations with dermacentor andersoni larvae. each exposure consisted of 100 larvae, and the first and second infestations were separated by a seven-day tick-free period. tick-exposed animals were given an intravenous injection with sheep red blood cells (srbc) at selected times during and after infestation: (a) the last, fifth day, of a first exposure, (b) the second day of a second infestation, (c) the fifth day of a second infestation and (d) fou ...19853913388
demonstration of anaplasma marginale in hemolymph of dermacentor andersoni by animal inoculation and by fluorescent-antibody technique.hemolymph was collected from adult dermacentor andersoni stiles that had been infected with anaplasma marginale theiler as nymphs. before hemolymph was collected, the adult ticks were either incubated and unfed at 37 c for 2.5 days or fed for 6 days on sheep. hemolymph collected from groups of 100 ticks was inoculated into susceptible splenectomized calves. smears of hemolymph from the same groups of ticks were prepared for examination by fluorescent antibody technique. hemolymph from incubated ...19836346968
isolation and molecular cloning of a secreted immunosuppressant protein from dermacentor andersoni salivary gland.a 36-kda immunosuppressant protein (da-p36) was isolated from salivary glands of feeding female ixodid ticks dermacentor andersoni, using its affinity for ultralink biosupport medium (pierce, rockford, illinois)/protein complexes. using a nested set of forward degenerate oligonucleotide primers corresponding to da-p36 n-terminal amino acids, a cdna encoding the immunosuppressant protein was isolated by 3' rapid amplification of cdna ends. the resulting 772-base pair cdna encodes a novel protein ...200010864249
expression of anaplasma marginale major surface protein 2 variants in persistently infected ticks.anaplasma marginale, an intraerythrocytic ehrlichial pathogen of cattle, establishes persistent infections in both vertebrate (cattle) and invertebrate (tick) hosts. the ability of a. marginale to persist in cattle has been shown to be due, in part, to major surface protein 2 (msp2) variants which are hypothesized to emerge in response to the bovine immune response. msp2 antigenic variation has not been studied in persistently infected ticks. in this study we analyzed msp2 in a. marginale popula ...200111447197
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 ...200717580573
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.200818167559
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 ...200819120212
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.200919857248
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 ...200919960693
the recent evolution of a maternally-inherited endosymbiont of ticks led to the emergence of the q fever pathogen, coxiella burnetii.q fever is a highly infectious disease with a worldwide distribution. its causative agent, the intracellular bacterium coxiella burnetii, infects a variety of vertebrate species, including humans. its evolutionary origin remains almost entirely unknown and uncertainty persists regarding the identity and lifestyle of its ancestors. a few tick species were recently found to harbor maternally-inherited coxiella-like organisms engaged in symbiotic interactions, but their relationships to the q fever ...201525978383
dermacentor reticulatus: a vector on the rise.dermacentor reticulatus is a hard tick species with extraordinary biological features. it has a high reproduction rate, a rapid developmental cycle, and is also able to overcome years of unfavourable conditions. dermacentor reticulatus can survive under water for several months and is cold-hardy even compared to other tick species. it has a wide host range: over 60 different wild and domesticated hosts are known for the three active developmental stages. its high adaptiveness gives an edge to th ...201627251148
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 ...200919284965
tick-borne diseases of sheep and goats caused by babesia, theileria or anaplasma spp.a review is given on the babesia, theileria, and anaplasma species infecting sheep and goats. b. ovis is the most important disease agent. it is transmitted by rhipicephalus bursa, r. turanicus, hyalomma anatolicum excavatum, and probably by r. evertsi evertsi b. ovis is widely spread in southern europe, the middle east, and central asia. its geographical distribution in south and east asia and in africa is widely unknown. b. motasi obviously represents several nosodemes in separate regions. it ...19979530692
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 ...200919129114
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