非洲猪瘟疫情防控的关键举措

非洲猪瘟(African Sswine Fever,AsF)是一种急性、热性、高度接触性传染病,2018年8月在我国首次发现。本文结合国内外非洲猪瘟防控研究实践,就如何进行非洲猪瘟的防控和根除进行了分析总结,以期为各地非洲猪瘟防控工作提供参考。     

Assessment of serological response of young and adult sheep to conjunctival vaccination with Rev-1 vaccine by fluorescence polarization assay (FPA) and other serological tests for B. melitensis

The serological response of young and adult sheep vaccinated conjunctivally with Rev-1 vaccine was assessed by fluorescence polarization assay (FPA), Rose Bengal test (RBT), complement fixation test (CFT), modified Rose Bengal test (m-RBT), indirect ELISA (i-ELISA) and competitive ELISA (c-ELISA), at different post vaccination intervals. One hundred and thirty six adult sheep and 64 lambs were used in the study. The vaccinated animals were bled prior to vaccination (0 day) and thereafter at 21st, 42nd, 35th, 63rd, 91st, 125th, 159th, and 223rd and 330th day post vaccination. The majority of animals (young and adult) showed positive reaction by FPA, RBT, CFT, m-RBT and c-ELISA 21 days post vaccination, whereas by i-ELISA at 42 days. All tests perform equal when animals vaccinated as young are tested 125 days (4 months) post vaccination. In case of animals vaccinated at adulthood, FPA, RBT, CFT and c-ELISA perform equal if the animals are tested 223 days (approximately 8 months) post vaccination. I-ELISA and m-RBT show low specificity if ewes vaccinated at adulthood are tested 330 days (11 months) post vaccination. If control of brucellosis in sheep is based on conjunctivally vaccination of lambs with Rev-1, the vaccinated animals can be tested by any test used for diagnosis of B.melitensis infection accurately at least 4 months post vaccination. If brucellosis control is based on mass vaccination the use of m-RBT and i-ELISA is not recommended for testing adult animals at least for 330 days (11 months) post vaccination due to tests low specificity. Further research is needed so the appropriate cut-offs to be established for FPA, c-ELISA or i-ELISA to become valuable tools for the eradication of Brucella spp. infection in small ruminants in areas where vaccination is practiced.     

一步法RT-PCR检测血清混合样品在BVDV清除计划中的应用

利用一步法RT-PCR对58份BVDV抗原阳性血清进行检测。试验证明,对OD450=0.3的标准血清,该方法的最低检出限为5μL/头,血清混合检测时至少可将60份OD450〉0.3的阳性血清等量混合。此外,RT-PCR与ELISA-Ag联合使用时,数学推导证明当混合样品为10～30个/份时,BVDV清除计划检测成本最低,相比单独使用ELISA-Ag,成本至少下降70%。综上,本试验确立的一步法RT-PCR灵敏度高,特异性好,联合ELISA-Ag使用,可大幅降低BVDV清除计划的检测成本,故值得推广使用。     

Removal of nonnative fish results in population expansion of a declining amphibian (mountain yellow-legged frog, Rana muscosa)

The mountain yellow-legged frog (Rana muscosa) was once a common inhabitant of the Sierra Nevada (California, USA), but has declined precipitously during the past century due in part to the introduction of nonnative fish into naturally fishless habitats. The objectives of the current study were to describe (1) the effect of fish removal from three lakes (located in two watersheds) on the small, remnant R. muscosa populations inhabiting those lakes, and (2) the initial development of metapopulation structure in each watershed as R. muscosa from expanding populations in fish-removal lakes dispersed to adjacent habitats. At all three fish-removal lakes, R. muscosa population densities increased significantly following the removal of predatory fish. The magnitude of these increases was significantly greater than that observed over the same time period in R. muscosa populations inhabiting control lakes that remained in their natural fishless condition. Following these population increases, R. muscosa dispersed to adjacent suitable (but unoccupied) sites, moving between 200 and 900 m along streams or across dry land. Together, these results suggest that large-scale removal of introduced fish could result in at least partial reversal of the decline of R. muscosa. Continued monitoring of R. muscosa at the fish-removal sites will be necessary to determine whether the positive effects of fish eradication are sustained over the long-term, especially in light of the increasingly important role played by an emerging infectious disease (chytridiomycosis, caused by Batrachochytrium dendrobatidis) in influencing R. muscosa populations.     

副溶血弧菌在鱼鳞表面形成生物被膜的动态过程及酸性电解水对其清除效果

运用电子扫描显微镜和胞外聚合物分析法研究副溶血弧菌在最适生长温度(37℃)条件下在鱼鳞表面形成生物被膜的动态过程、不同温度条件下在鱼鳞表面形成生物被膜的情况以及酸性电解水对其清除效果。结果表明:(1)在37℃条件下,12～60 h时间段内,细菌由初始的单细胞吸附发展成为具有明显三维立体网状结构的成熟生物被膜,60～72 h时间段内生物被膜表面产生裂痕。生物被膜的量在形成的动态过程中出现变化,12～60 h时间段内生物被膜的量不断增加,60～72 h时间段内生物被膜的量出现了轻微的减少;(2)副溶血弧菌在4、10、15、25、37和40℃条件下于鱼鳞表面生长60 h后均可以形成生物被膜,其形成生物被膜的量由高到低的次序是:37℃25℃40℃15℃10℃4℃;(3)酸性电解水对所有温度条件下形成的生物被膜均有良好的清除效果,处理后生物被膜变得稀疏,三维立体网状结构被破坏,连续处理10 min对胞外多糖和胞外蛋白的清除率分别达到64.54%和61.42%。     

伪狂犬病病毒感染抗体监测及伪狂犬病流行状况分析

在北京大兴和顺义区2个使用伪狂犬病病毒（porcine pseudorabies virus,PRV）Bartha株基因缺失疫苗的规模化猪场进行为期3年的猪伪狂犬病野毒感染抗体跟踪监测,并进行猪场的临床状况和组织样品的PCR检测,结果显示,北京市2011—2012年间在猪伪狂犬病基因缺失疫苗免疫猪场发生了猪伪狂犬病的流行。提示,应对该状况加以重视,对其发病原因需进行进一步的病毒分离和毒株分子遗传学分析。     

瑞士减群法在猪肺炎支原体净化中的应用研究进展

猪支原体肺炎（猪气喘病）是由猪肺炎支原体引起的一种严重危害全球养猪业生产的传染病之一,可以感染任何日龄和任何品种的猪只,且一旦侵入就难以清除。很多发达国家,特别是西欧和北美,均通过彻底净化病原的方式来控制该病的爆发。然而每个猪场都有各自的特殊性,完全套用其他猪场的模式未必能成功。瑞士减群法因其成本低、操作简便、成功率高,灵活多用而被很多猪场活用,本研究就瑞士减群法在不同猪场成功的活用做一综述,为国内猪肺炎支原体净化提供临床经验和理论依据。