Resistance to ETEC F4/F18–mediated piglet diarrhoea: opening the gene black box

Diarrhoea, a significant problem in pig rearing industry affecting pre- and post-weaning piglets is caused by enterotoxigenic Escherichia coli (ETEC). The ETEC are classified as per the fimbriae types which are responsible for bacterial attachment with enterocytes and release of toxins causing diarrhoea. However, genetic difference exists for susceptibility to ETEC infection in piglets. The different phenotypes found in pigs determine their (pigs’) susceptibility or resistance towards fimbrial subtypes/variants (F4ab, F4ac, F4ad and F18). Specific receptors are present on intestinal epithelium for attachment of these fimbriae, which do not express to same level in all animals. This differential expression is genetically determined and thus their genetic causes (may be putative candidate gene or mutations) render some animals resistant or susceptible to one or more fimbrial subtypes. Genetic linkage studies have revealed the mapping location of the receptor loci for the two most frequent variants F4ab and F4ac to SSC13q41 (i.e. q arm of 13th chromosome of Sus scrofa). Some SNPs have been identified in mucin gene family, transferring receptor gene, fucosyltransferase 1 gene and swine leucocyte antigen locus that are proposed to be linked mutations for resistance/susceptibility towards ETEC diarrhoea. However, owing to the variety of fimbrial types and subtypes, it would be difficult to identify a single causative mutation and the candidate loci may involve more number of genes/regions. In this review, we focus on the genetic mutations in genes involved in imparting resistance/susceptibility to F4 or F18 ETEC diarrhoea and possibilities to use them as marker for selection against susceptible animals.

     

仔猪ETEC F4受体研究进展

猪病给养猪生产造成的经济损失约占总产值的12％～15％（施启顺,2001）。仔猪腹泻在动物生产中是一种非常普遍的疾病,仔猪在断奶前和断奶后腹泻发病率均占6％～7％（Svensmark等,1989）。断奶前腹泻致死头数占出生仔猪头数的2．7％和同期死亡头数的11．9％（Nielsen等,1974）,达25kg体重平均日龄比正常个体晚2d,导致生产效率下降3％（Svensmark等,1989）。而且,断奶前发生胃肠道疾病的仔猪,在断奶后更容易发生腹泻和其它疾病感染。     

Adjuvant effect of Gantrez®AN nanoparticles during oral vaccination of piglets against F4+enterotoxigenic Escherichia coli

In this study, the adjuvanticity of methylvinylether-co-maleic anhydride (Gantrez^®AN) nanoparticles (NP) was investigated in an oral immunisation experiment of pigs against F4+enterotoxigenic Escherichia coli (F4+ETEC). In addition, Wheat Germ Agglutinin (WGA)-coating of the nanoparticles was tested for enterocyte-targeting. Pigs were either vaccinated with F4 fimbriae, F4 encapsulated in Gantrez^®AN NP, F4 encapsulated in Gantrez^®AN NP coated with WGA or F4 fimbriae mixed with empty Gantrez^®AN NP. Only vaccination with the combination of F4 mixed with empty Gantrez^®AN NP improved protection against F4+ETEC infection. In addition, vaccination with this formulation also resulted in an F4-specific serum antibody response prior to F4+ETEC challenge. Encapsulation of F4 in Gantrez^®AN NP only raised the serum antibody response after F4+ETEC challenge compared to soluble F4, but did not improve protection, whereas WGA-coating almost completely abolished the serum antibody response. These data indicate that nanoparticle effects after F4 encapsulation were of lesser importance for the adjuvant effect of Gantrez^®AN NP, contrarily to the reactivity of the Gantrez^®AN polymer used to prepare the nanoparticles.     

猪肠毒素大肠杆菌F4受体研究进展

猪肠毒素大肠杆菌F4(ETECF4)是引起1～2周龄仔猪黄、白痢最普遍、危害最大的大肠杆菌，ETECF4能否致病，决定于猪的小肠上皮细胞有无ETECF4受体，该受体由基因控制。本综述了ETEC F4受体的研究进展，提出了今后深入研究和抗病育种的可能途径。     

Evaluation of agronomic traits and nutrient absorption of an F4 recombinant inbred line of Chinese milk vetch (Astragalus sinicus)北大核心CSCD

In this research an F4 inbred line of Chinese milk vetch was constructed using Minzi No.7 milk vetch (Astragalus sinicus) as the female parent and the variety Xinyang as the male parent. For 18 strains in this population, the agronomic traits and nutrient absorption status were evaluated in a pot experiment at the full flowering stage, in order to use the results as a reference for screening superior milk vetch strains. Differences between plant strains were found. Correlation analysis showed that fresh weight, dry weight and accumulation of nitrogen, phosphorus and kalium were highly correlated, and were drivers of plant nutrient absorption, while plant height, branch number and leaf number were important factors affecting the fresh weight and dry weight of the plant. Principal component analysis showed that the main indexes such as shoot fresh and dry weights, and accumulation of nitrogen, phosphorus and kalium in the shoots could be used as indexes of Chinese milk vetch performance. In cluster analysis with the distance coefficient d=25, the 18 tested strains could be classified into three groups, of which Group Ⅰ had 4 strains (m83xzh-1-4-4, m83xzh-1-4-6, m83xzh-1-4-8, and m83xzh-1-4-13) with excellent multivariate trait scores. The best performing Chinese milk vetch strain in this evaluation was m83xzh-1-4-4. For this strain, the total plant nitrogen, phosphorus and kalium nutrient accumulation, accumulation of phosphorus and kalium in the shoots and accumulation of nitrogen and kalium in the roots were highest among the18 strains tested and were 11.00 mg·pot-1, 145.18 mg·pot-1, 22.15 mg·pot-1 and 15.27 mg·pot-1, respectively. The herbage fresh yield of m83xzh-1-4-4 was 44.63 g·pot-1 and ranked second among the 18 strains tested. This study provides technical data which may be useful in future breeding work to develop new milk vetch varieties. © 2022, Editorial Office of Acta Prataculturae Sinica. All rights reserved.     

仔猪产肠毒素大肠杆菌F4受体研究进展

猪肠毒素大肠杆菌F4(ETEC F4)是引起1～2周龄仔猪黄、白痢最普遍、危害最大的大肠杆菌。ETEC F4能否致病,决定于猪的小肠上皮细胞有无ETEC F4受体。本文综述了ETEC F4的黏附模式,F4特异受体在猪小肠中的分布,受体的生化特性,受体编码基因的定位、克隆现状及存在的问题,并对今后F4受体的研究方向及应用前景进行了展望。     

禽副粘病毒2型F4分离株F基因的克隆和变异分析

克隆了分离自七彩纹鸟的禽副粘病毒2型F4分离株F基因的全长,对它的生物特性进行了较为详细的研究,并试图通过与标准株Yucaipa株进行全面的比较,探讨该变异株的变异情况.研究结果表明:在电镜形态结构上,这两个毒株没有明显的差异;而血凝抑制交叉反应以及F基因序列同源性比较、疏水性和预测的二级结构比较分析显示它存在一些较为重要的变异,这对于禽副粘病毒2型病毒的流行病学分析有着重要的意义.     

仔猪产肠毒素大肠杆菌F4受体研究进展

仔猪腹泻是养猪生产中的一种常见病和多发病,也是困扰规模化养猪生产的主要难题之一。其中,产肠毒素大肠杆菌(ETEC)是造成新生和断奶仔猪腹泻的最主要病原体。文章综述了产肠毒素大肠杆菌F4受体的数量性状基因座(QTL)定位、候选基因以及单核苷酸多态性(SNP)发现,并对今后F4受体研究的问题解决及系统验证进行了展望,以期为培育种猪抗腹泻病新品系奠定理论基础。     

美洲狼尾草宁杂4号杂交种F1代与F2代的比较

应用杂种优势理论培育的种内、种间杂交种的Ｆ１代个体或群体的表型和产量性状均表现明显的杂种优势和超亲，产量超过亲本或其他品种２０％～３０％以上。但在Ｆ２代以后，植株性状分离，优势逐渐下降，产量降低。失去杂交制种和生产利用价值。对此，在玉米、高梁、水稻等粮食作物生产上，只能利用Ｆ１代种子，而Ｆ２代种子是不能用于生产的，这已被农民认识；但在为获得绿色体的牧草生产上，利用Ｆ２、Ｆ３代建植草地，影响牧草的鲜草及籽实产量，而造成减产的问题，农民尚未意识到。由于建植草地利用的Ｆ１代杂交种自留、自繁、自用，造成…     

川楝素对妊娠小鼠子宫组织中CD4+/CD8+T细胞和F4/80+巨噬细胞的影响

为探讨CD4+、CD8+ T淋巴细胞和F4/80+巨噬细胞在流产发生机制中的意义,研究中药单体成分川楝素诱导小鼠流产的作用及机理,本试验给妊娠5 d小鼠连续3 d腹腔注射不同剂量的川楝素溶液,对照组以等量的蒸馏水代替,于妊娠9 d处死.在给药后发现随着注射川楝素剂量的增加,小鼠的流产率逐渐上升,CD4+、CD8+ T淋...     

利用绿色荧光蛋白标记产肠毒素大肠杆菌F4ac

利用电击转化法将表达绿色荧光蛋白（green fluorescent protein,GFP）的原核表达载体pTurboGFP-B转化到产肠毒素大肠杆菌（enterotoxigenic Escherichia coli,ETEC）F4ac中，获得表达绿色荧光的菌株ETEC F4ac-GFP。聚合酶链式反应（polymerase chain reaction,PCR）结果显示，转化菌株表达绿色荧光蛋白编码基因，且可以在蓝光仪和荧光显微镜下清晰地观察到转化菌株发出绿色荧光；将ETEC F4ac-GFP与IPEC-J2细胞系进行体外粘附试验，在细胞水平验证了转化菌株荧光表达的稳定性与可靠性，且ETEC F4ac导入荧光质粒后不改变其对宿主细胞的胞粘附能力。CCK-8(Cell Counting Kit-8)和实时荧光定量PCR(qRT-PCR)结果表明，ETEC F4ac导入荧光质粒后不改变其对宿主细胞的毒力。本研究为深入探究ETEC F4ac致病机理提供了工具菌株。     

Increased Frequency of Double Ovulations after Induction of Luteolysis with Exogenous Prostaglandin F2α

The effect of induction of luteolysis by intramuscular treatment with prostaglandin F2α (PGF) on the frequency of double ovulations and formation of hemorrhagic anovulatory follicles (HAFs) was studied. The PGF (5 mg) was given 10 days after ovulation (n = 47 estrous cycles). No treatment or sham injection was used for control estrous cycles (n = 39). After treatment, the mares were scanned by transrectal ultrasonic imaging every 2 days until the largest follicle reached 25 mm and every day thereafter until the outcome of all follicles of at least 25 mm was determined. The frequency of two ovulations during the posttreatment ovulatory period was greater (P < .03) in the treated group (17%) than in the controls (3%). The combined frequency of two ovulations or one ovulation and one HAF also was greater (P < .002) in the treated group (30% vs. 5%). Equine veterinarians should be aware that PGF induction of luteolysis may increase the frequency of double ovulations or HAFs.     

1/4世纪的经验

一个男人在一个公司工作了25年。25年里,他每天用同样的方法做着同样的工作,每个月领着同样的薪水。一天,愤愤不平的男人决定要求老板给他加薪及晋升。在和老板谈话时,他向老板概述了他提出这样一个要求的理由。＂毕竟,＂他总结道,＂我已经有了1/4世纪的经验。＂     

Multiple-class antimicrobial resistance surveillance in swine Escherichia coli F4, Pasteurella multocida and Streptococcus suis isolates from Ontario and the impact of the 2004–2006 Porcine Circovirus type-2 Associated Disease outbreak

The objective of this work was to describe trends in multiple-class antimicrobial resistance present in clinical isolates of Escherichia coli F4, Pasteurella multocida and Streptococcus suis from Ontario swine 1998–2010. Temporal changes in multiple-class resistance varied by the pathogens examined; significant yearly changes were apparent for the E. coli and P. multocida data. Although not present in the E. coli data, significant increases in multiple-class resistance within P. multocida isolates occurred from 2003 to 2005, coinciding with the expected increase in antimicrobials used to treat clinical signs of Porcine Circovirus Associated Disease (PCVAD) before it was confirmed. Prospective temporal scan statistics for multiple-class resistance suggest that significant clusters of increased resistance may have been found in the spring of 2004; months before the identification of the PCVAD outbreak in the fall of 2004.     

ETEC F4-F5融合基因表达及间接ELISA方法建立

表达产肠毒素性大肠杆菌(enterotoxigenic Escherichia coli,ETEC)黏附素F4和F5融合蛋白,建立间接ELISA方法,旨在监测猪场ETEC感染以及疫苗免疫情况。根据GenBank中登录F4和F5基因序列,分析保守区,优化密码子,合成F4-F5串联基因,克隆入原核表达载体,表达重组蛋白His-F4-F5。以纯化的His-F4-F5蛋白作为检测抗原,建立检测ETEC抗体的间接EIISA方法。经酶切和DNA序列分析,成功构建重组菌BL21(pCold I-F4-F5),SDS-PAGE和Western blot分析,融合表达F4-F5相对分子质量为29 000,与ETEC高免血清发生特异性反应,条带单一。经优化筛选的间接ELISA最佳反应条件:抗原包被浓度6ng/孔,待检血清稀释比例1∶200,HRP-羊抗猪二抗的工作浓度1∶15 000,5%脱脂奶封闭l h,底物作用时间15min。本研究建立F4-F5间接ELISA方法具有特异性好、敏感性高、重复性好、稳定性强的特点,是猪场ETEC感染和疫苗免疫效果检测的有效工具,进而指导疫苗使用和新型疫苗研发。     

F4大肠杆菌黏附素受体易感性仔猪的体外鉴定研究

猪小肠上皮细胞表面的产肠毒素大肠杆菌(ETEC)F4受体的基因型与其粘蛋白4(MUC4)基因密切相关,根据MUC4基因内含子7能否被限制性内切酶XbaⅠ酶切,可以在基因水平上将所检测的猪分为ETEC F4易感型纯合子SS,易感型杂合子SR和抵抗型RR。为筛选对ETEC F4受体易感性和抗性仔猪用于本实验室的后续实验,本实验利用MUC4基因的多态性,对送检猪的样品进行初步的分型检测。选取MUC4基因内含子7不同等位基因型的仔猪,分离其小肠上皮细胞,并分别与野生型F4ab、F4ac、F4ad大肠杆菌,表达fae操纵子的重组大肠杆菌r F4ab、r F4ac、r F4ad进行体外黏附和黏附抑制试验。研究结果表明,上述野生菌或重组菌对SS和SR两种基因型的4周龄断奶大白仔猪小肠上皮细胞均具有较好的黏附能力,而且经过抗F4单克隆抗体处理后的细胞,对细菌的黏附数明显下降。而RR型仔猪小肠上皮细胞不能黏附上述野生菌或重组菌。本研究为体外鉴定F4受体易感性仔猪,以及为进一步研究ETEC F4的致病机理奠定了基础和平台。     

4株NDV分离株F基因的克隆与序列分析

对4 株具有一定代表性的NDV(新城疫病毒)分离株的F基因进行RT PCR(反转录聚合酶链反应)扩增和序列分析,根据基因裂解位点的氨基酸序列推测,其中1 株属于弱毒株,3 株属于强毒株;核苷酸序列及其推导的氨基酸序列比较结果表明,3株强毒株与Clone30 基因核苷酸序列的同源性在83.6%~84.0%之间,与F48 E9典型NDV强毒株同源性在86.5.6%~88.3%之间,推导的氨基酸序列同源性与Clone 30 株在85.9%~87.0%之间,与F48E9典型NDV强毒株在89.1%~91.3%之间;利用MegAlign软件绘制了NDV 的系统发育进化树,结果表明, 3株分离强毒株为Ⅶ基因型,弱毒株为基因Ⅱ型。     

The optimal immunization procedure of DNA vaccine pcDNA–TA4–IL-2 of Eimeria tenella and its cross-immunity to Eimeria necatrix and Eimeria acervulina

The immunization procedure of DNA vaccine pcDNA–TA4–IL-2 of Eimeria tenella, including route, dose, time of immunization and age of primary immunization of chicken, was optimized. The stability and the cross-species protection of the vaccine were also analyzed. Efficacy of immunization was evaluated on the basis of oocyst decrease ratio, lesion score, body-weight gain and the anti-coccidial index (ACI). Chinese Yellow chickens were randomly distributed into corresponding groups (30/group). The challenged, unchallenged and vector control groups were designed. The results illustrated that 25 μg was the optimal dose and intramuscular injection was the most effective route to induce protective immunity. There were no significant differences of ACIs between boosting and non-boosting groups. Storage time and temperature had little effect on the immunizing efficacy of the vaccine. The vaccine could provide partial cross-protection against the challenge with E. necatrix and E. acervulina, but not with E. maxima.