非洲猪瘟诊断制品注册评审现状分析

2018年8月，非洲猪瘟在我国沈阳首次爆发，随后蔓延至全国，给我国养猪业造成了重大经济损失。利用诊断制品对猪群非洲猪瘟感染情况进行检测与早期诊断，是预防和控制非洲猪瘟的有效手段。2019年以来，非洲猪瘟诊断制品注册申报数量居高不下，但常因申报资料存在各种问题未通过注册评审。鉴于此，对我国非洲猪瘟诊断制品注册申报情况、评审评价政策以及不符合注册要求的原因进行了分析，并提出了相关建议，供非洲猪瘟诊断制品研发、注册人员参考。     

非洲猪瘟病毒重组载体疫苗激发/加强免疫策略的初步研究

为了选择合理的非洲猪瘟病毒（ASFV）重组载体的激发/加强免疫策略，构建表达ASFV CD2v-p30-p54融合抗原的重组伪狂犬病毒rPRV-F1，将其与表达相同融合抗原的重组腺病毒rAd-F1分为rAd-F1/rAd-F1、rAd-F1/rPRV-F1、rPRV-F1/rPRV-F1、rPRV-F1/rAd-F1 4个组合进行猪免疫试验，分别于免疫后不同时间采血并分离血清进行ELISA抗体检测，分离的外周血单个核细胞（PBMC）经ASFV抗原刺激后进行IFN-γ检测。免疫荧光与免疫转印试验结果显示，构建的rPRV-F1能在感染细胞中正确表达F1融合蛋白。所有免疫猪均能检测到抗原特异性抗体，加强免疫后的抗体水平显著升高。在测试的4个免疫方案中，尽管rAd-F1/rAd-F1组合初次免疫后的抗原特异性抗体水平和IFN-γ表达水平最高，但加强免疫后的抗体水平和IFN-γ表达水平最低。与此相反，尽管rPRV-F1/rAd-F1组合初次免疫后的抗体水平和IFN-γ表达水平最低，但加强免疫后的抗体水平和IFN-γ表达水平最高。这些研究结果表明rPRV/rAd是较好的ASFV重组载体疫苗的激发/加强免疫策略。     

理化因素对非洲猪瘟病毒灭活效果的研究

【目的】了解我国非洲猪瘟病毒(African swine fever virus,ASFV)的生物学特性及理化抗性，提高猪场生物安全水平以防控非洲猪瘟。【方法】通过红细胞吸附试验和qPCR试验验证不同理化因素(包括静置、温度、UVC照射、室内外干燥、阳光暴晒和消毒剂)对ASFV的灭活效果。【结果】UVC照射30 min即可灭活病毒，照射时间越长，ASFV核酸降解越严重；室内干燥2.5 d、室外干燥1.5 d、阳光暴晒30 min均可灭活ASFV，但不能降解ASFV核酸；常见消毒剂对ASFV的杀灭效果良好，各消毒剂按照推荐稀释浓度室温作用15或30 min，除碘酸混合溶液外均能使ASFV完全失活；温度升高(4、25和37℃)会增强消毒剂的消毒作用；有机物FBS的存在会削弱消毒剂的作用，且随FBS体积分数增加(0、10%和30%)消毒剂的消毒效果会降低。【结论】本文系统研究了常见的理化因素对ASFV灭活效果的影响，有助于全面了解ASFV生物学特性，对非洲猪瘟的防控具有重要指导意义。     

三类常用消毒剂对非洲猪瘟病毒灭活效果的评价

为评价戊二醛类、酚类、含氯类常用消毒剂对非洲猪瘟病毒(ASFV)的灭活效果,参考OIE参考实验室相关操作流程,基于畜禽栏舍、运载工具、器具消毒目的,根据说明书标明的浓度范围选择低、中、高3个工作浓度,与ASFV分别在4℃和20℃条件下作用30 min,10倍连续稀释后接种猪肺泡巨噬细胞,同时加入猪红细胞,培养观察红细胞...     

一种自适应逐级开运算的原木端面识别方法

为提高原木检尺的工作效率，提出一种自适应逐级开运算的成堆原木端面识别方法，以实现自然环境下成堆原木端面的快速识别。获取自然环境下堆放的成堆原木图像，利用PSO改进的K-Means聚类算法基于图像的RGB色差值，对图像进行背景和目标的分割，用PSO算法寻找K-Means的初始聚类中心，通过背景和原木堆的聚类实现背景和目标的分割。对于分割后的图像，设计了一种自适应原木端面大小的逐级开运算原木端面识别方法，该方法根据图像中的目标原木大小，以圆面积计算公式中面积和半径的正比关系为依据，用半径作为结构元素，从而自适应地寻找出结构元素的最大值和最小值，在2个最值的区间内设定1个可变的结构元素，从最大值逐渐减少地对目标图像进行开运算，从而实现对图像中不同直径大小的原木识别，计算出原木堆图像中所有原木的根数。结果表明，使用逐级开运算进行原木识别，对清楞原木的检测达到平均正检率97.26%，漏检率2.74%，错检率8.10%；混楞原木检测正检率93.32%，漏检率6.68%，错检率7.02%；与使用Hough变换进行圆检测的方法相比，本算法清楞原木和混楞原木的正检率平均提高分别为16.24%和19.29%。自适应逐级开运算的原木端面识别方法，可以识别不同直径的成堆原木端面，从而实现原木根数的自动计算，能有效提高人工检尺的效率。     

急性非洲猪瘟脑损伤及NF-κB介导脑水肿形成机制研究

【目的】 在试验条件下研究非洲猪瘟病毒（African swine fever virus，ASFV）所致急性脑损伤及核因子κB （NF-κB）介导脑水肿发生的相关病理机制。【方法】 18头健康长白猪随机分为2组，攻毒组（13头）和对照组（5头），攻毒组肌内注射剂量为10²HAD₅₀/mL （HAD₅₀：半数红细胞吸附量）的ASFV毒株Pig/HLJ/18，对照组注射等体积生理盐水，试验期为15 d。试验期间观察临床症状，剖检死亡猪并观察脑部病变；利用原位PCR检测进行病毒定位；HE染色及甲苯胺蓝染色观察脑组织病理变化；免疫组化染色法检测脑组织中肿瘤坏死因子-α（TNF-α）、白介素-1β（IL-1β）、干扰素-γ（IFN-γ）、NF-κB、基质金属蛋白酶9（MMP-9）、水通道蛋白4（AQP-4）的表达。【结果】 攻毒组9头猪表现出临床神经症状，脑部剖检病变主要为脑膜充血和不同程度的脑实质水肿；ASFV主要位于脑部微血管中；病变早期主要为脑水肿，脑皮质区结构疏松、血管周围间隙增宽、神经元肿胀变圆、染色变淡，中后期除了表现脑水肿的特征外，还可见脑血管充血、多量微血栓形成及淋巴细胞浸润；免疫组化结果显示，攻毒组TNF-α、IL-1β、IFN-γ、NF-κB及MMP-9主要在神经元及胶质细胞中表达，AQP-4的阳性细胞主要是微血管周围的星形胶质细胞，与对照组相比，攻毒组上述6种因子的阳性表达率均极显著增高（P<0.01）。【结论】 急性非洲猪瘟脑损伤的主要表现为脑膜血管充血出血和脑实质水肿、组织学病变显示病毒性脑炎，ASFV感染脑部，促进炎性因子的异常高表达，通过激活NF-κB信号通路对TNF-α、IL-1β、IFN-γ的转录进行调控，使这几种炎性因子的产生和释放增多，扩大炎症反应，影响血脑屏障的通透性，还能上调MMP-9与AQP-4的表达，破坏血脑屏障，促进脑水肿的发生发展。     

非洲猪瘟疫情对中国居民肉类消费的影响

为了明确非洲猪瘟疫情发生后国内居民肉类消费结构的变动趋势，给后续制定和实施稳定生猪市场的政策提供依据，同时也能为以后研究其他动物疫病暴发后居民肉类消费行为变动提供一定参考。基于2015—2020年全国31个省（市、区）（除港澳台外）的面板数据，采用双重差分法从理论与实证两方面探究非洲猪瘟对居民肉类消费结构的影响，并运用调节效应模型对其作用机理进行验证。研究发现：第一，非洲猪瘟导致我国居民人均肉类消费总量下降明显，其中猪肉下降趋势最显著，禽肉作为猪肉的主要替代品消费量显著上升，虽然牛羊肉也起到了替代作用，但结果不显著。第二，非洲猪瘟对城乡居民肉类消费影响存在明显差异，农村居民与全国总体居民的消费变化方向一致，并且农村居民受非洲猪瘟影响更大；对城镇居民而言，非洲猪瘟也会降低其肉类总消费量和猪肉消费量，但并不显著，与农村居民不同的是禽肉与牛肉共同成为城镇居民选择的猪肉替代品。第三，居民可支配收入在非洲猪瘟对居民肉类总量与猪肉的消费影响中有显著调节作用，非洲猪瘟发生后可支配收入越低的省份，肉类总量与猪肉的消费下降越多。     

A multiplex real-time PCR assay for simultaneous detection of classical swine fever virus,African swine fever virus,and atypical porcine pestivirus

With the implementation of the C-strain vaccine, classical swine fever (CSF) has been under control in China, which is currently in a chronic atypical epidemic situation.  African swine fever (ASF) emerged in China in 2018 and spread quickly across the country. It is presently occurring sporadically due to the lack of commercial vaccines and farmers’ increased awareness of biosafety.  Atypical porcine pestivirus (APPV) was first detected in Guangdong Province, China, in 2016, which mainly harms piglets and has a local epidemic situation in southern China.  These three diseases have similar clinical symptoms in pig herds, which cause considerable losses to the pig industry.  They are difficult to be distinguished only by clinical diagnosis.  Therefore, developing an early and accurate simultaneous detection and differential diagnosis of the diseases induced by these viruses is essential.  In this study, three pairs of specific primers and Taq-man probes were designed from highly conserved genomic regions of CSFV (5´ UTR), African swine fever virus (ASFV) (B646L), and APPV (5´ UTR), followed by the optimization of reaction conditions to establish a multiplex real-time PCR detection assay.  The results showed that the method did not cross-react with other swine pathogens (porcine circovirus type 2 (PCV2), porcine reproductive and respiratory syndrome virus (PRRSV), foot-and-mouth disease virus (FMDV), pseudorabies virus (PRV), porcine parvovirus (PPV), and bovine viral diarrhea virus BVDV).  The sensitivity results showed that CSFV, ASFV, and APPV could be detected as low as 1 copy mL^–1; the repeatability results showed that the intra-assay and inter-assay coefficient of variation of ASFV, CSFV, and APPV was less than 1%.  Twenty-two virus samples were detected by the multiplex real-time PCR, compared with national standard diagnostic and patented method assay for CSF (GB/T 27540–2011), ASF (GB/T 18648–2020), and APPV (CN108611442A), respectively.  The sensitivity of this triple real-time PCR for CSFV, ASFV, and APPV was almost the same, and the  compliance results were the same (100%).  A total of 451 clinical samples were detected, and the results showed that the positive rates of CSFV, ASFV, and APPV were 0.22% (1/451), 1.3% (6/451), and 0% (0/451), respectively.  This assay provides a valuale tool for rapid detection and accurate diagnosis of CSFV, ASFV, and APPV.     

Farmers' perception of vegetation changes in semi‐arid Niger

Vegetation changes due to climate and human impact in Sahelian countries are rarely documented at species composition level. The decrease or disappearance of certain plant species reduces vegetation cover and enhances the exposure of soil surfaces to wind and water erosion leading to increased land degradation. Men and women in Niger were asked to note plant species and relate their numerical development to pre‐defined observation criteria comparing the present and past. Plant species in decline or that had disappeared were reported more often than species that had increased or were newly introduced. The increasing species that were mentioned were often in use for different purposes and seem to be robust enough and well adapted to the semi‐arid environment. But the interviewed farmers also stated the loss of many valuable species that they used for construction and hand tools, consumption, medicine or fodder. Those declining species are of socio‐economic importance for individual households and the rural ecology. Men mentioned 18 species that had disappeared. Differences in the perception of men and women could be found. Women seemed to have a better perception for species which had increased or were newly introduced, whereas men perceived more a decrease or disappearance of species. Copyright © 2000 John Wiley & Sons, Ltd.     

Optimal design of culling compensation policy under the African swine fever — Based on simulations of typical pig farms in China

This paper aims to optimize the culling compensation policy from a micro perspective through scenario simulation. Based on an investigation of 273 pig farms in eight regions, four typical pig farms were constructed according to farm size and breeding mode, representing the swine producers in China. Besides, a decision objective function of pig farms facing suspected African swine fever (ASF) outbreaks was constructed. This study used a mathematical programming model to design and simulate scenarios based on compensation standards and local implementation levels, aiming to incentivize pig farms to report epidemics. The results show that the optimal decisions on epidemic reports differed among typical farms and by herd daily age. The results suggest the following adjustments for optimizing culling compensation policies: (1) to set culling compensation standards based on the market value and (2) to maintain a high level of epidemic surveillance capability in the animal husbandry and veterinary sector.