A polyetic modelling framework for plant disease emergence

Plant disease emergences have dramatically increased recently as a result of global changes, especially with respect to trade, host genetic uniformity, and climate change. A better understanding of the conditions and processes determining epidemic outbreaks caused by the emergence of a new pathogen, or pathogen strain, is needed to develop strategies and inform decisions to manage emerging diseases. A polyetic process-based model is developed to analyse conditions of disease emergence. This model simulates polycyclic epidemics during successive growing seasons, the yield losses they cause, and the pathogen survival between growing seasons. This framework considers one immigrant strain coming in a single event into a system where a resident strain is already established. Outcomes are formulated as probability of emergence, time to emergence, and yield loss, resulting from deterministic and stochastic simulations. An analytical solution to determine a threshold for emergence is also derived. Analyses focus on the effects of two fitness parameters on emergence: the relative rate of reproduction (epidemic speed), and the relative rate of mortality (decay of population between seasons). Analyses revealed that stochasticity is a critical feature of disease emergence. The simulations suggest that: (a) emergence may require a series of independent immigration events before a successful invasion takes place; (b) an explosion in the population size of the new pathogen (or strain) may be preceded by many successive growing seasons of cryptic presence following an immigration event; and (c) survival between growing seasons is as important as reproduction during the growing season in determining disease emergence.     

Serological evidence for influenza virus infection in Korean wild boars

Serum samples from 1,011 wild boars hunted in 2012 were collected for serological surveillance for 4 subtypes (pandemic A (H1N1) 2009 and classical H1N1, H1N2 and H3N2) of swine influenza virus (SIV). Samples from 12 of the boars were identified as positive for SIV (pandemic A (H1N1) 2009, n=9; classical H1N1, n=2; and H1N2, n=1) by a hemagglutination inhibition test (HI test) and a nucleoprotein (NP)-based enzyme-linked immunosorbent assay (NP-ELISA). Although the overall seroprevalence of SIV in the Korean wild boar population was somewhat low compared with that in China and the U.S.A., the apparent prevalence of pandemic H1N1 was notable. Therefore, continuous monitoring of the wild boar population is needed as it may be a major reservoir for pandemic H1N1, facilitating its spread to humans and domestic pigs.     

猪伪狂犬病病毒灭活疫苗对猪伪狂犬病病毒流行毒株和经典毒株的免疫保护效果评估

为评估猪伪狂犬病病毒（Pseudorabies virus,PRV）灭活疫苗（HN1201-ΔgE株）免疫后对PRV流行毒株和经典毒株的保护效果,本研究对试验猪分别免疫PRV灭活疫苗（HN1201-ΔgE株）和PRV活疫苗（Bartha-K61）,免疫后第0、7、10、14、17、21、24和28天采血测定PRV gB抗体,并分别使用PRV流行毒株HN1201株和经典毒株闽A株测定免疫后第0、7、14、21和28天血清的中和抗体水平,于免疫后第28天分别使用HN1201株和闽A株攻毒并观察,之后测定体温,测定攻毒后第7和14天PRV gE抗体,及攻毒后0~8 d的排毒情况。结果显示,HN1201-ΔgE免疫组较Bartha-K61免疫组gB抗体和中和抗体产生早,且抗体水平较高。两个免疫组试验猪在攻毒后虽然均无明显临床症状,且免疫组织化学检测（IHC）组织中的病毒抗原均为阴性,但HN1201-ΔgE免疫组试验猪脏器未见任何病理损伤,Bartha-K61免疫组试验猪部分脏器具有病理损伤。与未免疫对照组相比,2个免疫组试验猪在HN1201株和闽A株攻毒后,gE抗体转阳时间晚且排毒率低,HN1201-ΔgE免疫组gE抗体水平整体均低于Bartha-K61免疫组,攻毒后排毒检测中,Bartha-K61免疫组于2个毒株攻毒后第3~5天可检测到排毒,而HN1201-ΔgE免疫组全程未检测到排毒。研究结果表明,灭活疫苗（HN1201-ΔgE株）对PRV流行毒株和经典毒株均可提供完全保护。     

生物制剂防治柳树舞毒蛾幼虫试验

柳树舞毒蛾在石家庄市各县区都有分布且危害很大,为了能找到经济有效且对环境无影响的防治方法,特用BT粉剂和灭幼脲三号两种生物制剂进行试验,比较两种制剂使用的最佳浓度及药效,为大面积使用生物制剂提供可靠的依据。     

Serological Evidence of Pandemic H1N1 Influenza Virus Infections in Greek Swine

The introduction of the 2009 pandemic H1N1 (pH1N1) influenza virus in pigs changed the epidemiology of influenza A viruses (IAVs) in swine in Europe and the rest of the world. Previously, three IAV subtypes were found in the European pig population: an avian‐like H1N1 and two reassortant H1N2 and H3N2 viruses with human‐origin haemagglutinin (HA) and neuraminidase proteins and internal genes of avian decent. These viruses pose antigenically distinct HAs, which allow the retrospective diagnosis of infection in serological investigations. However, cross‐reactions between the HA of pH1N1 and the HAs of the other circulating H1 IAVs complicate serological diagnosis. The prevalence of IAVs in Greek swine has been poorly investigated. In this study, we examined and compared haemagglutination inhibition (HI) antibody titres against previously established IAVs and pH1N1 in 908 swine sera from 88 herds, collected before and after the 2009 pandemic. While we confirmed the historic presence of the three IAVs established in European swine, we also found that 4% of the pig sera examined after 2009 had HI antibodies only against the pH1N1 virus. Our results indicate that pH1N1 is circulating in Greek pigs and stress out the importance of a vigorous virological surveillance programme.     

Urban park use and self-reported physical,mental, and social health during the COVID-19 pandemic: An on-site survey in Beijing,China

The COVID-19 pandemic created unprecedented challenges for people’s health. Studies have demonstrated the positive impact of urban green spaces, particularly urban parks, on physical and mental health. However, few studies have evaluated social health, which is a component of human health, and more understanding of the relationship between urban parks and human health during the COVID-19 pandemic is required. This study examined the effects of urban parks on people’s health using a canonical correlation model. Physical, mental, and social health were the dependent health variables, and five factors related to urban parks were the independent variables. This study investigated 22 urban parks inside the Forth Ring Road in Beijing, China using a questionnaire survey. The results demonstrated a positive association between urban parks and human health during the pandemic. Distance to the parks, park area, and park size were positively correlated with physical, mental, and social health. Furthermore, frequency and duration of visits to urban parks were positively associated with mental health and contact with neighbors. The health effects of urban park use varied with park types and locations’ urbanization background. These findings can provide insights for health-oriented urban park planning and construction.     

新冠肺炎疫情对运城蔬菜产业的影响及对策

新冠肺炎疫情的发生对运城市蔬菜产业发展产生了一定的影响,经调查总结发现主要表现在农资进村受阻、生产用工短缺、种苗供应难、蔬菜销售不畅4个方面。为了提高运城市应对重大突发事件的能力,确保人们的"菜篮子"丰富充盈,提出了鼓励在蔬菜主产区补充建设蔬菜集约化育苗场、大力推进运城市蔬菜产业现代化进程、多措并举拓宽蔬菜销售渠道、多方配合保障农资供应畅通等发展建议。     

Pig farmers' willingness to recover their production under COVID-19 pandemic shock in China – Empirical evidence from a farm survey

Pig farmers' willingness to recover production under the COVID-19 pandemic shock is significant to recover live pigs' supply in China in 2020. Increasing farmers' willingness to recover pig production contributes to enhance pig supply, stabilize the pig and pork market, and to improve pig farmers' income. This research studies the determinants of pig farmers' willingness to recover production under COVID-19 pandemic shock by applying survey data of 201 farmers in Huai'an City and Lin'an City and a logit regression model. The estimation results show that a farmer's risk perception, the duration time of a farmer's feed supply under COVID-19 pandemic shock, whether or not being a cooperative member, and a farmer's knowledge on government's policy designed to encourage pig production, a farmer's education level and production experience are the key determinants to a farmer's willingness to recover pig production. Thus, it's important for policymakers to solve the problems for farmers to get access to feed during the pandemic, to encourage the development of cooperatives, as well as to issue and advocate policies to encourage pig production. The study contributes to the scant literature by providing fresh empirical evidences on determinants of farmers' willingness to recover pig production. It has significance to farmers and governments to enhance farmers' willingness to recover production, which contributes to secure pig supply in China after the COVID-19 pandemic.     

整合H1亚型流感病毒血凝素蛋白伪型病毒的构建

为构建包装含有H1亚型流感病毒HA蛋白的伪型病毒,本研究将人工合成的H1N1流感病毒(A/Califorma/04/2009株)血凝素(Hemagglutinin,HA)基因连接至真核表达载体pcDNA3.1,该重组质粒与表达逆转录病毒相关元件的骨架质粒pHIT111及pHIT60共转染人胚胎肾细胞293T,构建了以鼠白血病病毒为核心、包装含有HA蛋白的伪型病毒.通过对伪病毒感染细胞中LacZ报告基因表达产物的检测,证明伪病毒可以感染MDCK细胞;同时其感染过程可被流感病毒免疫后的小鼠阳性血清所阻断,表明该伪型病毒可模拟野生型病毒完成对宿主细胞的感染过程.本研究所构建的伪病毒系统为研究H1亚型流感病毒HA蛋白抗原特性及新型中和抗体检测方法的建立提供了理想的工具.     

新型冠状病毒肺炎疫情下小龙虾产业发展对策——以湖北省荆州市为例

新型冠状病毒肺炎疫情对荆州市小龙虾养殖-物流-加工-餐饮全产业链造成了严重冲击，短期内恢复难度大，企业、新型经营主体信心不足。经历了连续多年的快速发展后，在疫情影响下，小龙虾产业呈现出新的变化：一是养殖面积趋于稳定，稻田养殖将回归理性，由“大养虾”向“养大虾”转变；二是小龙虾储藏和精深加工产业发展；三是线上消费模式将越来越被接受。基于调查研究，提出了小龙虾产业恢复生产与持续健康发展的相关建议：养殖端要从产量增长向质量提升转变，加工、服务端要开发新产品、发展新消费模式，行业管理部门要加大引导、监管力度，政府要从政策、金融、宣传等方面加强扶持，共同引导产业升级，打造区域品牌。