O型口蹄疫病毒各编码基因及其产物变异率的分析

将从Genbank中提出的20株O型FMDV的全基因组分割成12个编码区域,即Lab、VP4、VP2、VP3、VP1、2A、2B、2C、3A、3B、3C和3D.通过方差分析,12个编码序列的相对变异率之间无差异(P>0.05);而这12种编码序列所对应的氨基酸相对突变率之间差异显著(P<0.01).利用Duncan法对这12种氨基酸序列相对突变率进行多重比较,发现3A蛋白的氨基酸相对突变率比其余11种蛋白的差异都显著(P<0.05);VP2、Lpro的氨基酸相对突变率与VP4、2A、2C、3Cpro、3Dpol之间存在差异(P<0.05);而VP4、2A、2C、3Cpro、3Dpol之间无差异.结果显示,O型FMDV自身RNA的转录和机体对FMDV施加的免疫压力不是造成FMDV变异的主要原因,而各种病毒产物的功能选择压力才是FMDV分子进化的主要原因.     

Aspects of emergency vaccination against foot-and-mouth disease

Emergency vaccination is one of several measures which may be deployed to control outbreaks of foot-and-mouth disease. It can be a valuable adjunct to the application of the essential zoosanitary controls which must include rapid diagnosis, tracing, movement control and disinfection and which may also include slaughter of infected and in-contact animals and their safe disposal. Criteria which determine the successful application of emergency vaccination include access to vaccine(s) that (i) contain virus strain(s) of sufficient antigenic relatedness to the outbreak strain(s) (ii) are of the required type of vaccine formulation (iii) have acceptable innocuity and potency (iv) have appropriate availability, including quantity and immediacy of supply and (v) meet considerations of cost. Contingency planning should include provision for emergency vaccination and must address the complex decisions of not only when, where, and how to apply vaccine but also its economic consequences. Computer modelling may be a useful aid to cost benefit and decision support systems in this context. Planning must be detailed and regularly reviewed and should ensure, (i) that the legal and financial aspects are catered for (ii) that any contractual supply agreements are in place (iii) that information is collected and its currency maintained on the species, numbers and whereabouts of susceptible livestock (iv) that vaccination teams are formed and trained (v) that the vaccine cold chain is established and maintained (vi) that supplies of vaccination equipment are held in readiness and (vii) that briefing materials are available to inform the various stakeholders on relevant aspects of emergency vaccination. Knowledge concerning the characteristics and performance of emergency vaccines is summarised and areas identified for further research.     

A decision-tree to optimise control measures during the early stage of a foot-and-mouth disease epidemic

A decision-tree was developed to support decision making on control measures during the first days after the declaration of an outbreak of foot-and-mouth disease (FMD). The objective of the tree was to minimise direct costs and export losses of FMD epidemics under several scenarios based on livestock and herd density in the outbreak region, the possibility of airborne spread, and the time between first infection and first detection. The starting point of the tree was an epidemiological model based on a deterministic susceptible–infectious–recovered approach. The effect of four control strategies on FMD dynamics was modelled. In addition to the standard control strategy of stamping out and culling of high-risk contact herds, strategies involving ring culling within 1 km of an infected herd, ring-vaccination within 1 km of an infected herd, and ring-vaccination within 3 km of an infected herd were assessed. An economic model converted outbreak and control effects of farming and processing operations into estimates of direct costs and export losses. Ring-vaccination is the economically optimal control strategy for densely populated livestock areas whereas ring culling is the economically optimal control strategy for sparsely populated livestock areas.     

Use of heterogeneous operation-specific contact parameters changes predictions for foot-and-mouth disease outbreaks in complex simulation models

The role of contact parameters in a complex spatial simulation model of foot-and-mouth disease spread was determined by comparing predictions of number of infected premises, epidemic duration, and relative infection risk for different production sectors between a model that included the Full, heterogeneous (differing by production type) type-specific information about animal, vehicle and personnel movement between premises, and models that used partial and homogeneous (similar across production types) weighted-mean or proxy parameter sets for contacts between premises of all types. The model was run using a dataset of known premises locations in a three-county area in the Central Valley of California and categorized into 13 premises types and six production sectors.Results from models run with homogeneous contact parameters were always different from those obtained from the Full model, demonstrating that model predictions are affected by heterogeneity in contact parameters. Models simplified by using weighted-mean parameters predicted fewer infected premises. Models that were simplified by using medium dairy farm or large swine operation proxy parameters predicted longer epidemics with more infected premises, while those using small beef operation proxy parameters predicted shorter epidemics with fewer infected premises. Simplified-parameter models underestimated the impact on the economically important dairy sector, while overestimating the impact on beef and backyard operations. Results establish a need for heterogeneous, operation-specific contact parameters in complex stochastic simulation models that must be weighed against the cost of obtaining and coding premises type-specific contact information.     

C型口蹄疫病毒型特异性抗原的表达与鉴定

[目的]为C型FMDV型特异性多克隆抗体、单克隆抗体的制备及FMDV定型提供理论依据。[方法]以含有C型口蹄疫病毒（FMDV）结构蛋白基因VP1的重组质粒pGEM—CP1为模板,设计特异性表达引物,扩增VP1及其C端编码区。对C型口蹄疫病毒VP1及其C端进行原核表达,并测定反应原性。利用纯化的C型VP1及其C端融合蛋白建立间接ELISA,分别对O、A、C、Asia14型豚鼠阳性血清进行检测,确定C型VP1及其C端与其他3型FMDV抗体的型间交叉反应性。[结果]构建了pPRO-CVP1、pPRBO-CVP1c重组原核表达质粒,实现了C型口蹄疫病毒VP1及其C端的高效表达,目的蛋白的分子量大小分别为33和20kD。Westernblot显示。VPl及其C端融合蛋白均可与对应血清型的豚鼠阳性血清反应。C型VP1及其C端与其他血清型的FMDv阳性血清均未发生交叉反应。且以VP1c端的型特异性最好。[结论]获得了C型FMDV特异性抗原。     

口蹄疫基因工程疫苗研究进展

介绍了口蹄疫在世界范围内暴发流行的现状及其疫苗的研究应用,重点综述了各种口蹄疫基因工程疫苗的研究进展。     

猪口蹄疫的综合防控

口蹄疫是由口蹄疫病毒(Foot-and-mouth disease virus, FMDV)感染引起偶蹄动物共患的急性、热性、高度接触性传染病,最易感染的动物是黄牛、水牛、猪、骆驼、鹿、羊等;黄羊、麝、野猪、野牛等野生动物也易感染此病。世界动物卫生组织将其列为A类动物传染病,我国将其列为I类动物疫病。文章从口蹄疫病原的特性、流行病学、临床特征及病理变化等方面对口蹄疫的防控措施进行了总结、阐述。     

RT-PCR evaluation for identification and sequence analysis of foot-and-mouth disease serotype O from 2006 to 2007 in Punjab, Pakistan

FMD clinically positive 250 tissue samples (mouth and hoof epithelium and vesicle swabs, tongue tissue) and 175 secretion samples (milk, saliva, serum, plasma) were evaluated by RT-PCR for the diagnosis of FMD with different pair of universal and serotype-specific primers from 2006 to 2007 in Punjab, Pakistan. Universal primer pair P1/P2 from VP1 gene detected FMD in 182 out of 250 (72.8%) tissues and 92 out of 175 (52.6%) secretion samples, while universal primer 1F/1R from 5′UTR region detected FMD in 218 out of 250 (87.2%) tissues and 142 out of 175 (81.1%) secretion samples. 1F/1R proved better than the P1/P2 primer pair for primary diagnosis of FMD, direct from the clinical positive samples. Direct sequencing of the universal primer pair P1/P2 revealed that O serotype of FMD was circulating in this region. O serotype of FMD was detected with O-1C(ARS4)/PNK 61, AU(O)/AU(rev), AU(O)/PNK61 primer pairs, these primer pairs also compared with each other. AU(O)/AU(rev) and AU(O)/PNK61 detected O serotype of FMD in 88.9% tissue and swab (mouth and hoof vesicle swabs) samples and 71.9% different secretion (milk, saliva, serum, plasma) samples, while O-1C(ARS4)/PNK 61 detected 48.1% tissue and swab (mouth and hoof vesicle swabs) samples and 37.5% different secretion (milk, saliva, serum, plasma) samples. AU(O)/AU(rev), AU(O)/PNK61 primer pairs detected 40.8% more tissue and swab samples, while these pairs detected 34.4% more secretion samples. Cloning of PCR product of AU(O)/AU(rev) VP1 gene and sequencing for phylogenetic studies revealed that O serotype of FMD circulating in Punjab, Pakistan was genetically very diverse from the ‘O’ serotype in Middle East and Europe. The dendrogram showed that Pakistan ‘O’ serotype was very much similar genetically to its neighbor countries (Sri Lanka, India, Iran, Iraq, and China) and PanAsia 1 lineage which caused 2001-outbreak in UK and 1994-outbreak in Saudi Arabia, etc.     

抗口蹄疫病毒单克隆抗体1C7重轻链可变区基因的克隆及序列分析

应用分子生物学技术，从分泌抗O型口蹄疫病毒单克隆抗体的杂交瘤细胞1C7中提取总RNA，经反转录，PCR扩增及克隆，分别得到VH基因及VL基因。序列测定结果表明：1C7的VH基因为368bp,VL基因为323bp。用NCBI GenBank分析表明，VH和VL均符合小鼠抗体可变区特征，为功能性重排的抗体可变区基因。根据Kabat分类体系，1C7的VH基因中的VH基因片段隶属于抗体重链第7183家族，其VL基因中的VL基因片段隶属于抗体K轻链20家族，VH基因由VH76－1BG－DFL16．1－JH4重排而形成，VL基因由KVbw20-JK2重排而形成。1C7的VH和VL基因的克隆为抗FMDV scFv的构建与表达奠定了基础。     

The North American Animal Disease Spread Model: a simulation model to assist decision making in evaluating animal disease incursions

The North American Animal Disease Spread Model is a stochastic, spatial, state-transition simulation model for the spread of highly contagious diseases of animals. It was developed with broad international support to assist policy development and decision making involving disease incursions. User-established parameters define model behavior in terms of disease progression; disease spread by animal-to-animal contact, contact with contaminated personnel or equipment, and airborne dissemination; and the implementation of control measures such as destruction and vaccination. Resources available to implement disease control strategies, as well as the direct costs associated with these strategies, are taken into consideration. The model records a wide variety of measures of the extent of simulated outbreaks and other characteristics. The graphical interface and output visualization features also make it a useful tool for training and preparedness exercises. This model is now being used to evaluate outbreak scenarios and potential control strategies for several economically important exotic animal diseases in the United States, Canada, and elsewhere. NAADSM is freely available via the Internet at http://www.naadsm.org.