为了解江苏省泰州市市售鸡蛋中黄曲霉毒素B1(AFB1)的污染情况,2020年采集不同超市、集贸市场的60个种类/批次的鸡蛋各30枚,每个种类/批次随机选取3枚,共180枚,采用商品化酶联免疫吸附试验(ELISA)试剂盒进行AFB1残留量测定.结果显示:在抽检的180枚鸡蛋样品中,15枚样品中有一定的AFB1残留,为0.20～0.64μg/kg,占8.33％,均为超市中不同场家产品,而集贸市场的鸡蛋(多为散养鸡所产)中AFB1残留量都很低.因此,规模化养殖场在蛋鸡饲养过程中要严格把控饲料质量,定期对饲料做好检测和监测.

犬细小病毒(CPV)自1978年被首次分离到以来,已由CPV-2演化出CPV-2a、CPV-2b和CPV-2c 3种新抗原型.为了解江苏省扬泰地区的CPV分子特征和基因型,2015年5月至2016年12月在扬州和泰州地区宠物医院,根据患病犬临床症状以及CPV快速检测试纸条初步诊断结果,收集可疑病例的泄殖腔棉拭子或粪便作为检测样品,扩增样本中CPV的VP2基因片段并对扩增产物进行测序和分析.结果显示:在48份样品中,4份被鉴定为CPV-2型,24份被鉴定为CPV-2a型,20份被鉴定为CPV-2b型,并未发现CPV-2c型.结果表明,该期间CPV-2a型与CPV-2b型成为扬泰州地区的优势基因型,需开展这些新基因型的深入研究和防控.

由于鸡新城疫抗体水平检测大赛测定方法参考国家标准《新城疫诊断技术》,而该标准并没有细化到每一个操作步骤,同时主办方提供的竞赛评分标准也不够详细,再加上每个参赛团队也没有统一的标准操作流程,为了取得更加优异的成绩,各竞赛团队追求的是操作技巧的不断完善提高.笔者对影响试验结果的诸多因素进行初步分析以供参考与借鉴.

RyhB is a kind of about 90 bp bacterial non-coding small RNA.It was reported that two RyhB homologs RyhB-1 and IsrE,which existed in the Salmonella typhimurium and Vibrio chol-erae could regulate biofilm formation,chemotaxis and acid resistance.To study the pathogenicity and cooperative function of RyhB-1 and IsrE,we constructed ryhB-1 and isrE single and double deletion mutants by the λ-Red-based recombination system and corresponding complemented mutants by constructing complemented plasmid with pBR322 and pACYC184,and transferring to deletion mutants 50336ΔryhB-1,50336ΔisrE and 50336ΔryhB-1/ΔisrE.Then we tested the pathogenic differences of wild type,ryhB-1 and isrE deletion mutants and complemented mutants by inoculating above strains to 1-day-old chickens and detecting LD501,mortality rate and bacterial distribution in chickens.The results showed that the virulence of Salmonella enteritidis was decreased in the ryhB-1 or isrE gene deletion strain,especially in ryhB-1 and isrE double deletion strain.It indicated that ryhB-1 and isrE gene could enhance pathogenicity of Salmonella enteritidis.The two sRNAs have a cooperative effect in virulence regulation.

Bovine viral diarrhea virus is divided into two genotypes:genotype 1 (BVDV-1) and genotype 2 (BVDV-2).Previous epidemiological survey showed BVDV-1 isolates distributed more widely.However,the mobidity rate of BVDV-2 is increasing in recent years.In general,BVDV-2 infection can cause more severe disease characterized by acute infection and haemorrhagic syndrome,causing enormous losses to the cattle industry.In this review,we dilate on the following aspects:the establishment of the specific detection and genotyping methods of BVDV-2,the isolation and identification of BVDV-2,complete genomic sequencing and phylogenetic analyzation of BVDV-2 isolates,and the establishment of detection platform to virus and antibody of BVDV-1 and BVDV-2.

为研究肠炎沙门氏菌鞭毛素对其生物膜形成的影响,本研究利用构建的肠炎沙门氏菌鞭毛素编码基因fliC缺失株,检测其缺失性修饰后的生长表型变化及其对生物膜形成的影响.结果显示在表型检测试验中,fliC缺失株在电镜下观察呈无鞭毛形态,在半固体培养基上缺乏运动性,并且不能与肠炎沙门氏菌鞭毛单克隆抗体发生可见的凝集反应.生物膜形成能力定性试验结果表明,肠炎沙门氏菌fliC缺失株生物膜形成大量减少,并且生物膜脆弱,而其回补株能够较好地恢复生物膜的形成;生物膜定量结果进一步证明,鞭毛素fliC基因缺失后肠炎沙门氏菌形成生物膜的能力下降50％左右,以上结果显示鞭毛在肠炎沙门氏菌体外生物膜形成中具有重要作用.

为了解某鸡场沙门茵临床分离株血清型分布与药物敏感性,以常规方法从病死雏鸡分离出多株细菌,经形态学观察、生化试验、PCR检测和血清型定型,最终鉴定出10株沙门茵,其中2株为肠炎沙门菌,8株为鸡白痢沙门菌.采用Kindy-Bauer(KB)法检测分离菌株对25种抗菌药物的敏感性表明,菌株均为多重耐药菌株,对阿奇霉素等12种药物的耐药率达到70％以上,而对复达欣等13种药物的敏感率均高于70％.结果表明,沙门菌早期感染仍是造成雏鸡高死亡率的重要病因之一,长期以来抗茵药物在养鸡业上的不合理使用已对沙门茵的耐药谱产生了明显影响,给沙门菌的临床防控带来了新的挑战.

为研发以禽伤寒沙门氏菌(SG) SG9R弱毒疫苗株为载体表达外源基因的活菌疫苗,本研究利用Red同源重组系统对SG9R株基因组中编码天冬氨酸β-半醛脱氢酶的asd基因进行敲除,构建SG9R△asd缺失突变株.该突变株在缺乏外源DAP培养条件下溶菌死亡,而在添加DAP或导入表达链球菌asd+质粒pYA3342后才能够恢复增殖能力,以此建立了以asd营养基因为筛选标志的SG染色体-质粒平衡致死系统.并且进一步采用绿色荧光蛋白(GFP)基因作为报告基因,将其克隆于asd+质粒pYA3342中,电转化于SG9R△asd缺失突变株中,通过无DAP培养条件的筛选,获得了表达GFP外源基因的SG重组菌,经体外连续25次传代后,鉴定结果显示,GFP仍能够在重组SG中持续稳定的表达.本研究结果为以SG弱毒疫苗菌株作为活载体的基因工程疫苗的研制提供简便易行的操作平台.

禽流感是当今全球范围内最为严重的禽类传染病之一.该病病原禽流感病毒能感染多种禽类,由于毒株毒力和宿主易感性的差异,致使感染呈现出急性致死、轻度呼吸道感染、隐性感染等多种形式.近年来的流行病学资料表明,禽流感病毒的毒力正不断增强,从而导致禽类易感性增高.对于禽流感的致病机理目前尚未有明确的解释.研究以1株鸡源流感病毒为研究对象,从不同水平观察各种禽类感染后组织器官的病变情况,旨在了解新形势下禽流感病毒感染的病理学特点,明确该病的致病机理.

Abstrcat Susceptibility of different birds to waterfowl-origin influenza viruses--ZM strain from muscovy and SG strain from goose was studied inoculated via intravenous or intramuscular route. Results showed that chickens, quails, patridges were included as highly susceptible host. Geese and muscovy-ducks were also susceptible,while shaoxing-ducks and broiler-ducks were resistant to infection with the viruses. Pigeons had resistance too.

将禽流感病毒番鸭分离株ZM的感染性鸡胚尿囊液静脉或肌肉接种不同禽类,同时设鸡源JC株对照,以了解毒株的致病特点.结果显示ZM株与同期分离JC株致病能力相当,两毒株均对鸡、鹅、番鸭、鹌鹑和鹧鸪显示了很强的致病能力,致死率为50%～100%,死亡禽类的肝、肾、肺、脾、胰腺等多个组织器官均存在严重的损伤.鸽子,肉鸭和绍鸭(除ZM株致死一只绍鸭外)均未发生死亡,外观健康.