Clostridium piliforme infection (Tyzzer disease) in horses: retrospective study of 25 cases and literature review

Tyzzer disease (TD) is caused by Clostridium piliforme, a gram-negative and obligate intracellular bacterium. The disease occurs in multiple species. A triad of lesions, namely colitis, hepatitis, and myocarditis, is described in cases of TD in some species, such as rats and mice. We carried out a retrospective analysis of 25 equine cases with a diagnosis of TD; 24 of 25 cases occurred in foals <45 d old; the remaining foal was 90 d old. There were 12 males and 12 females; no sex information was available for one foal. The affected breeds were Quarter Horse, Thoroughbred, Arabian, Paint, and Hanoverian. Most of the cases (19 of 25) occurred in the spring. There were 9 cases of sudden death; the remaining animals had diarrhea, fever, distended abdomen, depression, weakness, non-responsiveness, and/or recumbency. Gross findings included icterus, hepatomegaly with acinar pattern, serosal hemorrhages, pulmonary edema, and/or fluid content in small and large intestine. Microscopically, all foals had severe, multifocal, necrotizing hepatitis. Necrotizing lymphohistiocytic colitis was observed in 10 of 25 foals, and multifocal necrotizing myocarditis was found in 8 of 25. Gram-negative, Steiner-positive, intracytoplasmic filamentous bacteria were observed in hepatocytes, enterocytes, and myocardiocytes, respectively. PCR detected C. piliforme DNA in the liver (24 of 24), colon (20 of 24), and heart (5 of 25). Our results indicate that necrotic hepatitis is the hallmark of TD in horses; the so-called triad of lesions is not a consistent characteristic of the disease in this species.     

高粱炭疽病研究进展

高粱作为中国主要的酿造原料之一,在国民经济发展中占据重要地位。高粱炭疽病是高粱的主要病害之一,在整个生育期中均可发病,且在温暖湿润的热带和亚热带栽种地区更易发生和流行,不仅影响植株的正常生长,严重时会引起产量的大幅下降和籽粒品质的劣变。多年来,高粱病理学家和育种家对高粱炭疽病病原菌菌株分离、病害发生流行规律、发生原因、寄主抗性利用和抗炭疽病基因定位等方面进行了广泛的研究,取得了一些进展。这些研究为炭疽病的生化防控以及培育抗炭疽病品种奠定了基础。开展高粱炭疽病研究,发掘更丰富多样的优异抗性种质资源,减少农药使用,不仅可以满足中国高粱产业对天然有机高粱原料的巨大需求,还可以推动高粱生产向高产优质转变。对高粱炭疽病的分布和发病症状、炭疽病病原菌侵染机理、病害发生流行规律及流行原因、抗性资源鉴定和高粱抗炭疽病基因定位的相关研究进展进行了综合分析和论述,以期从分子水平上更好地认识高粱与炭疽病病原菌之间的相互作用,为高粱炭疽病研究提供参考。     

A reovirus disease in cultured mud crab, Scylla serrata, in southern China

A reovirus, designated mud crab reovirus (MCRV), associated with large economic losses was recently isolated from marine cultured mud crab, Scylla serrata, in southern China. The complete viral particle is 70 nm in diameter, icosahedral and non-enveloped. The virus infects connective tissue cells of the hepatopancreas, gills and intestine in mud crab and develops in the cytoplasm. Hundred per cent mortality was observed in mud crab experimentally infected by intramuscular injection, bath inoculation and oral inoculation, while cohabitation infection caused 80% mortality. The viral genome consists of 13 linear dsRNA segments, with an electrophoretic pattern 1/5/7. The results of this study suggest that the virus is highly pathogenic and can be transmitted enterically as well as via the body surface of mud crab. Although the genomic organization of this virus is different from that of the other crab reoviruses, CcRV-W2 and DpPV, all three of these reoviruses have similar electrophoresis patterns. Therefore, MCRV may be a new member of the DpPV and CcRV-W2 group.     

玉米小斑病抗性种质鉴定及生理生化分析

以200份玉米优良自交系为材料,2022-2023年夏分别进行小斑病菌的田间接种,综合两年数据共鉴定出高抗小斑病的玉米自交系3份,分别为K22、CML50和齐319;筛选到包括Mo17在内的抗性玉米自交系24份。选取K22和B73两个具有不同抗性水平的玉米自交系进行小斑病菌的室内接种。结果表明,48 h和72 h时,自交系K22叶片的病斑数、病斑面积和病斑面积比等各项指标均显著优于自交系B73,进一步验证田间鉴定的准确性。48 h或72 h时,高抗小斑病自交系K22与感病对照B73相比,5种防御酶活性增加14.32%～70.45%。     

奶牛肢蹄病的原因及防治措施

奶牛体重大,肢蹄部作为奶牛日常活动的重要支撑器官,容易发生变形、跛行和蹄裂等。笔者结合自身工作经验,从季节、营养、生产、管理因素分析奶牛肢蹄病的发病原因,对养殖场常见的腐蹄病、蹄叶炎和局限性蹄皮炎临床症状进行概述,并总结了奶牛肢蹄病的局部和全身治疗方案,提出科学选址和建场、制定护蹄保健制度、合理搭配营养和定期进行药浴4种预防肢蹄病的措施,供同行交流参考。     

不同药剂对水稻细菌性条斑病的防治效果评价

为有效控制水稻细菌性条斑病病害,科学合理选用防治正安县地区水稻菌性条斑病的杀菌剂,本研究以当地主要栽培水稻品种“宜香优2115”为试验材料,测定了60%唑醚·代森联、6%春雷霉素、20%吡唑醚菌酯、40%稻瘟灵对水稻菌性条斑病防治效果及生长发育和产量的影响。结果表明:不同药剂防治下水稻细菌性条斑病病情指数和防治效果间存在差异性显著(p＜0.05),20%吡唑醚菌酯对水稻细菌性条斑病的病情指数最低和防治效果最优;较喷施清水对照处理相比,60%唑醚·代森联、6%春雷霉素、20%吡唑醚菌酯和40%稻瘟灵施用时水稻叶面积指数和干物质积累量增幅分别为10.29%、13.48%、15.17%、12.92%和15.15%、16.77%、18.92%、17.31%;20%吡唑醚菌酯施用时的水稻穗粒数和产量最高,分别为61.76穗/粒和627.75kg/亩。本研究可为遵义市正安县地区水稻生产中细菌性条斑病的防治提供理论依据和数据支撑     

复方黄芪颗粒防治鸡传染性法氏囊病的疗效试验

应用复方黄芪颗粒对鸡传染性法氏囊炎病毒人工感染病例进行试验,结果表明,有效率达到80%~92%,治愈率达到68%~76%,均高于对照药物,差异极显著(P<0.01)。推荐剂量为每升饮水中加入1g复方黄芪颗粒,连用5 d。     

黑龙江省大豆疫霉根腐病调查与病原分离

１９９６年对黑龙江省东部和中部大豆产区２３个市、县的大豆苗期疫霉根腐病进行了调查、研究,应用ＰＢＮＩＣ疫霉选择性培养基分离大豆疫霉根腐病病原菌,从牡丹江、穆棱、林口和佳木斯豆田具疫霉根腐症状的大豆植株上分离到大豆疫霉根腐病菌,并从根腐病株上单独或与大豆疫霉菌同时分离到终极腐霉菌,研究进一步证实我国黑龙江省有大豆疫霉根腐病。调查发现,大豆疫霉根腐病和终极腐霉根腐病主要发生在土质粘重、土壤含水量高或易积水的田块。     

甘肃省定西市当归“水烂病”病原鉴定及致病性测定

水烂病是甘肃省当归上发生的一种病害.本试验对水烂病病原菌的形态特征、培养特性、生理生化指标进行了测定,同时结合16SrDNA序列测定和相似性比对,发现该病原菌与GenBank数据库已知荧光假单胞杆菌第2生物型(Pseudornonas fluorescens生物型Ⅱ)的序列相似性达99％,其片段大小为1445 bp,编号为ZB1.致病性测定结果表明,该病原菌对‘岷归2号’(新繁品种)致病力最强,‘岷归1号’(主栽品种)次之,对‘朝鲜当归’(引进品种)的致病力最弱.本研究首次报道了荧光假单胞杆菌第2生物型能引起当归水烂病.     

Use of real-time PCR to examine the relationship between disease severity in pea and <Emphasis Type="Italic">Aphanomyces euteiches</Emphasis> DNA content in roots

Aphanomyces euteiches causes severe root rot of peas. Resistance is limited in commercial pea cultivars. Real-time fluorescent PCR assay specific for A. euteiches was used to study the relationship between disease severity and pathogen DNA content in infected peas. Five pea genotypes ranging in levels of resistance were inoculated with five isolates of A. euteiches. Plants were visually rated for disease development and the amount of pathogen DNA in roots was determined using the PCR assay. The susceptible genotypes Genie, DSP and Bolero tended to have significantly more disease and more pathogen DNA than the resistant genotypes 90-2079 and PI 180693. PI 180693 consistently had less disease, while 90-2079 had the lowest amount of pathogen DNA. The Spearman correlation between pathogen DNA quantity and disease development was positive and significant (P < 0.05) for three isolates, but was not significant for two other isolates. This suggests that the real-time PCR assay may have limited application as a selection tool for resistance in pea to A. euteiches. Its utility as a selection tool would be dependent on the correlation between disease development and pathogen DNA content for a given pathogen isolate. The accuracy and specificity of the real-time PCR assay suggests considerable application for the assay in the study of mechanisms of disease resistance and the study of microbial population dynamics in plants.