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Experiments were conducted to determine comparative populations of Salmonella typhimurium in the most commonly infected body organs of long-term carrier swine. Naturally farrowed Salmonella-free pigs (n = 58) were orally exposed to S typhimurium when they were 47 days old. Necropsy of 3 to 5 randomly selected pigs was conducted at 3, 7, 10, 14, and 17 days and at 3, 4, 5, 6, 8, 12, 16, 20, 24, and 28 weeks after exposure. Mean populations (log10/g) of S typhimurium in palatine tonsils, ileum, cecum (wall and contents), ascending colon (wall and contents), and mandibular and ileocolic lymph nodes were estimated at each necropsy, using a most-probable-number method of bacteriologic examination. Populations of organisms in cecum and colon were similar to each other throughout the duration of the study. Mean populations (log10/g) associated with cecal and colonic walls decreased from 6.1 and 6.6, respectively, during the first postexposure (PE) week to less than or equal to 1.67 from PE weeks 4 to 28. Populations (log10/g) associated with cecal and colonic contents decreased from 5.6 and 5.5, respectively, at PE day 3 to 2.5 and 2.7, respectively, at PE week 4, and remained less than or equal to 2.8 until week 28. Populations (log10/g) associated with intestinal walls and contents were closely correlated during the study. Population (log10/g) in the ileum was greater than or equal to 5.3 from PE days 3 to 17, then varied between 5.4 and -0.4 up to PE week 28.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
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Erysipelothrix rhusiopathiae serotype 5 was isolated from blood obtained antemortem from a horse with presenting problems of laminitis, uveitis, acute blindness, localized ventral edema and depression. The patient failed to respond to therapy and died 96 hours after the onset of clinical signs. Cultures of the lung postmortem yielded Erysipelothrix rhusiopathiae serotype 5, Beta-hemolytic Streptococcus sp., Escherichia coli, Proteus sp., and Klebsiella sp. 相似文献
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Nemadectin, a new broad-spectrum endectocide, was highly efficacious against natural infections of all the major canine gastrointestinal helminths. At single oral dosages of 0.2-0.4 mg kg-1 body weight (BW), a liquid formulation administered in gelatin capsules was 100% effective in eliminating natural infections of Toxocara canis, Toxascaris leonina, Ancylostoma caninum and Uncinaria stenocephala. Tablets (267 mg) containing 4.6% nemadectin given at a rate of 1/3 tablet per 20 kg BW (0.2 mg nemadectin kg-1) were 100% active against T. canis, A. caninum and U. stenocephala. With both formulations, an increase in the dose rate to 0.6-0.8 mg kg-1 BW resulted in 99-100% elimination of Trichuris vulpis infections. No adverse reactions were observed in any of the treated dogs. 相似文献
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Bisset SA Vlassoff A McMurtry LW Elliott DC Cobb RM Kieran PJ Wood IB 《New Zealand veterinary journal》1992,40(3):97-100
The efficacy of an oral formulation of the newly developed parasiticide, moxidectin, was tested against benzimidazole-resistant Haemonchus contortus, Trichostrongylus colubriformis, and Nematodirus spathiger, levamisole-resistant Ostertagia circumcincta, and susceptible Cooperia curticei infections in weaned lambs. Thirty-two lambs were experimentally infected with mixed doses of the above strains of nematodes. They were allocated into four treatment groups by stratified randomisation using liveweights and faecal egg counts 28 days later. One group received moxidectin at 0.2 mg/kg liveweight, one group oxfendazole at 4.5 mg/kg liveweight, one group levamisole at 7.5 mg/kg liveweight and the last group remained untreated as the control. Worm burdens in the lambs at slaughter 10 days after oral treatment confirmed the resistance status of the nematode strains used, and showed that moxidectin had a greater than 99.9% efficacy (p<0.01) against all of them. No adverse effects due to treatment with moxidectin were observed in any of the animals. 相似文献
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A. Schots J. De Boer A. Schouten J. Roosien J. F. Zil Verentant H. Pomp L. Bouwman-Smits H. Overmars F. J. Gommers B. Visser W. J. Stiekema J. Bakker 《European journal of plant pathology / European Foundation for Plant Pathology》1992,98(2):183-191
Engineering resistance against various diseases and pests is hampered by the lack of suitable genes. To overcome this problem we started a research program aimed at obtaining resistance by transfecting plants with genes encoding monoclonal antibodies against pathogen specific proteins. The idea is that monoclonal antibodies will inhibit the biological activity of molecules that are essential for the pathogenesis. Potato cyst nematodes are chosen as a model and it is thought that monoclonal antibodies are able to block the function of the saliva proteins of this parasite. These proteins are, among others, responsible for the induction of multinucleate transfer cells upon which the nematode feeds. It is well documented that the ability of antibodies to bind molecules is sufficient to inactivate the function of an antigen and in view of the potential of animals to synthesize antibodies to almost any molecular structure, this strategy should be feasible for a wide range of diseases and pests.Antibodies have several desirable features with regard to protein engineering. The antibody (IgG) is a Y-shaped molecule, in which the domains forming the tips of the arms bind to antigen and those forming the stem are responsible for triggering effector functions (Fc fragments) that eliminate the antigen from the animal. Domains carrying the antigen-binding loops (Fv and Fab fragments) can be used separately from the Fc fragments without loss of affinity. The antigen-binding domains can also be endowed with new properties by fusing them to toxins or enzymes. Antibody engineering is also facilitated by the Polymerase Chain Reaction (PCR). A systematic comparison of the nucleotide sequence of more than 100 antibodies revealed that not only the 3′-ends, but also the 5′-ends of the antibody genes are relatively conserved. We were able to design a small set of primers with restriction sites for forced cloning, which allowed the amplification of genes encoding antibodies specific for the saliva proteins ofGlobodera rostochiensis. Complete heavy and light chain genes as well as single chain Fv fragments (scFv), in which the variable parts of the light (VL) and heavy chain (VH) are linked by a peptide, will be transferred to potato plants. A major challenge will be to establish a correct expression of the antibody genes with regard to three dimensional folding, assembly and intracellular location. 相似文献
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Tsutomu MATSUMOTO Yuichiro NARA Hiromitsu FURUYA Harumi TAKAHASHI Kiichi TAIRAKO Hideki YAMAMOTO 《Journal of General Plant Pathology》2002,68(4):382-384
L11A-Fukushima (L11A-F) derived from attenuated isolate LuA of Tomato mosaic virus (ToMV) has the highest ability to cross protect against virulent ToMV among LuA and its derivatives and is stably inherited.
Growth, yield, fruit quality and symptom attenuation of inoculated tomato plants did not differ significantly between L11A-F and L11A. The infectivity of progeny viruses in tomato infected with LuA-F was less than 4% of that with virulent ToMV. From these
results, L11A-F appears to possess the properties necessary for practical use. To manage L11A-F strictly, a PCR-based assay to detect trace contamination of virulent ToMV in L11A-F preparations was established.
Received 10 June 2002/ Accepted in revised form 30 October 2002 相似文献