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41.
This paper reports the results of tissue infectivity assays of bovine spongiform encephalopathy (BSE) agent in orally exposed cattle at stages during the incubation period. Estimations of the titre of infectivity in central nervous system (CNS), certain peripheral nerve ganglia and distal ileum tissue were made according to time post exposure from the relationship between incubation period and dose for RIII mice and C57bl mice using data from titrations of brain material from cases of BSE. The rate of increase of infectivity in the bovine CNS was then estimated, taking into account these tissue infectivity titres, the variability of the brain titre of clinical field cases of BSE, and the probability density of the expected number of months before clinical onset of each infected bovine. The doubling time for CNS was shown to equal 1.2 months. The titre in the thoracic dorsal root ganglia (DRG) was, on average, approximately 1 log units less than CNS, and cervical DRG approximately 0.5 log less than thoracic DRG. The pattern of increase of infectivity in the distal ileum is that of an initial increase up to 14-18 months post exposure, followed by a decrease, which is likely to be highly variable between animals. These results will be informative for future risk assessments of BSE, especially in relation to reviewing current control measures. 相似文献
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Qing Yu Mingzhu Liu Siting Wu Hehe Xiao Xinling Qin Pengfei Li 《Journal of fish diseases》2021,44(1):33-44
Grass carp reovirus (GCRV) causes devastating viral haemorrhagic disease in farmed grass carp (Ctenopharyngon idellus). As novel molecular probes, aptamers have been widely applied in rapid diagnosis and efficient therapies against virus or diseases. In this study, three single‐stranded DNA (ssDNA) aptamers were selected against GCRV‐infected CIK cells via SELEX (systematic evolution of ligands by exponential enrichment technology). Secondary structures predicted by MFOLD indicated that aptamers formed stem‐loop structures, and GVI‐11 had the lowest ΔG value of ?30.84 KJ/mol. Three aptamers could specifically recognize GCRV‐infected CIK cells, with calculated dissociation constants (Kd) of 220.86, 176.63 and 278.66 nM for aptamers GVI‐1, GVI‐7 and GVI‐11, respectively, which indicated that they could serve as specific delivery system for antiviral therapies. The targets of aptamers GVI‐1, GVI‐7 and GVI‐11 on the surface of GCRV‐infected cells could be membrane proteins, which were trypsin‐sensitive. Furthermore, FAM‐labelled aptamer GVI‐7 could be applied to detect GCRV infection in vivo. It is the first time to generate and characterize aptamers against GCRV‐infected cells. These aptamers have great potentials in development of rapid diagnosis technology and antiviral agents against GCRV infection in aquaculture. 相似文献
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猪圆环病毒Ⅱ型流行病学新特点及致病机理研究进展 总被引:1,自引:0,他引:1
猪圆环病毒是猪圆环病毒病的主要致病因素,该病给养猪业带来很大的经济损失。猪圆环病毒变异较快,是单链DNA病毒中最高的;易感猪主要通过消化道和呼吸道水平传播而感染,猪圆环病毒Ⅱ型(PCV2)人工或自然感染猪的排泄物、鼻腔、口腔和扁桃体拭子和患畜的尿液和粪便中均能检测到PCV2。断奶仔猪多系统衰竭综合征(PMWS)的发病主要与猪体内PCV2含量有关。PCV2特异抗体对猪群的PCV2感染具有保护作用。PCV2诱导猪继发性免疫缺陷,淋巴细胞缺失,影响PCV2感染结果的因素有:病毒、宿主、混合感染和免疫调节等。 相似文献
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长期以来,昆虫病原真菌作为一类重要的生防资源,在农林害虫种群自然调节中发挥了重要作用。综述了昆虫病原真菌资源的利用情况、对害虫的侵染致病机理及主要属种在农林害虫生防中的应用现状,分析了昆虫病原真菌防治中的限制因素,并指出了今后昆虫病原真菌研究利用中应加强的方面。 相似文献
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Chlamydophila pecorum found in the intestine and vaginal mucus of asymptomatic ruminants has also been associated with different pathological conditions in ruminants, swine and koalas. Some endangered species such as water buffalos and bandicoots have also been found to be infected by C. pecorum. The persistence of C. pecorum strains in the intestine and vaginal mucus of ruminants could cause long-term sub-clinical infection affecting the animal’s health. C. pecorum strains present many genetic and antigenic variations, but coding tandem repeats have recently been found in some C. pecorum genes, allowing C. pecorum strains isolated from sick animals to be differentiated from those isolated from asymptomatic animals. This review provides an update on C. pecorum infections in different animal hosts and the implications for animal health. The taxonomy, typing and genetic aspects of C. pecorum are also reviewed. 相似文献
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奶牛金黄色葡萄球菌性乳房炎研究进展 总被引:4,自引:0,他引:4
奶牛乳房炎是对世界奶牛业造成经济损失最大的疾病之一,它不仅直接导致乳品工业的经济损失,而且由于患乳房炎的奶牛其乳汁中经常含有大量的毒素、病原微生物以及治疗后残留的抗生素,使得该病日益引起公众的关注。金黄色葡萄球菌是奶牛乳房炎的主要病原,由于其极易产生耐药性,使得治疗变得相当困难,因此使用预防或治疗性疫苗防治乳房炎就成为首选。金黄色葡萄球菌对上皮细胞的黏附和侵袭力被认为是奶牛金黄色葡萄球菌性乳房炎的主要致病机制,金黄色葡萄球菌的致病力涉及到许多不同的毒力因子,如黏附素、荚膜、各种毒素和酶类等。研究表明,以这些毒力因子为靶位进行疫苗研究,可能是预防奶牛金黄色葡萄球菌性乳房炎的有效途径。 相似文献
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