从高热病猪组织血液内分离大肠埃希氏菌分析

通过分析分离自病猪血液、器官的细菌生物学特性,探讨高热病猪发病病因,寻找预防、治疗的方法。取3头高热病猪组织、血液用羊血及伊红美兰琼脂平板培养、分离出的3株菌株,经VITEK2革兰氏阴性细菌鉴定卡全自动微生物鉴定;ASTGN10药敏卡,药敏分析系统鉴定;小鼠毒力实验;血清凝集实验;16SrRNA基因鉴定;致泻毒力基因鉴定。结果3株均为大肠埃希氏菌(Escherichiacoli)大肠埃希氏菌,并经16SrRNA基因鉴定与GenBank比对结果,3株细菌均鉴定为大肠杆菌。3株菌对氨曲南、头孢吡肟等药物敏感,而对庆大霉素、四环素等耐药。菌株对小鼠有较强的致病力。菌株与159种大肠杆菌诊断血清均不凝集,说明这些菌不是常见的大肠杆菌致病型。致泻毒力基因鉴定均为阴性。分离出3株非常见致病型大肠杆菌在当地猪高热症暴发中起到重要作用。高热病猪尽早配合使用敏感抗生素治疗有减轻病情、减少病死率的效果。     

仔猪腹泻大肠埃希菌的分离鉴定及耐药性分析

为了解贵州省规模化养猪场仔猪腹泻致病大肠埃希菌流行及耐药情况,本试验应用细菌分离培养、形态学观察和生物化学鉴定等技术,对采集于贵州省规模化养猪场腹泻仔猪肠道内容物128份进行病原分离鉴定,并通过动物回归试验验证病原致病力、药敏试验分析其耐药特性。结果显示,本次试验共分离鉴定到78株大肠埃希菌。动物致病性试验显示,分离菌可在不同时间致死小鼠,表明分离菌具有较强的致病力;药敏试验结果显示,分离菌对β-内酰胺类药物青霉素耐药率最高,为94.87%(74/78),对磺胺类药物复方新诺明耐药率最低,为21.79%(17/78),对其余抗菌药物均表现出不同程度耐药;多重耐药结果显示,所有分离菌株均为多重耐药菌株,多重耐药主要表现在7～11耐,占分离菌株的83.33%(65/78)。研究结果为仔猪大肠埃希菌性腹泻的防控提供理论依据。     

鸡大肠杆菌病研究Ⅰ．鸡E．Coli人工感染模型的建立及致病力评价

本文对分离自典型大肠杆菌病变和粪便的４５株Ｅ．Ｃｏｌｉ通过４日龄雏鸡人工感染试验建立了大肠杆菌病的人工感染模型，并对菌株的致病性进行评价。结果表明：４日龄雏鸡颈部皮下接种０．２ｍｌ菌液，接种后，前６５ｈ内雏鸡死亡率≥６０％的菌株为强致病力菌株；死亡率＜６０％，或出现典型大肠杆菌病变为中等致病力菌株；试验期不引起雏鸡死亡也无病变者为无致病力大肠杆菌。试验的１３株分离自粪便的苗株，２株为中等致病力，１１株为无致病力；３２株分离自典型病变的菌，９株为强致病力菌，１５株为中等致病力，８株为无致病力。     

34株鸡大肠杆菌的分离鉴定及致病力分析

本研究从鸡泄殖腔取样,分离大肠杆菌菌株,进行生化鉴定。结果显示34株菌株符合大肠杆菌的培养特性。将分离得到的34株大肠杆菌与购买的4株鸡大肠杆菌分别接种鸡胚,对致病力进行分析。结果采用数据处理软件SPSS分析90%置信区间,其中19株为致病力较强菌株(致死率大于上限38.4%),16株为致病力较弱或无致病力菌株(致死率小于下限25.1%),3株为中等致病力菌株(致死率在上限和下限之间)。通过套式PCR对38株菌的iss基因进行检测,阳性率为100%。结果表明,iss基因(increased serum survival gene)在鸡大肠杆菌中广泛存在,38株鸡大肠杆菌均有iss基因,但致病力大小不同,故推测致病力大小可能与iss基因的存在无关。     

斑鳢细菌性败血症病原菌的分离与鉴定

由患细菌性败血症的斑鳢分离到１１株菌,根据直接荧光抗体法鉴定结果,对其中７株菌的菌落特性进行了观察,分析了菌株的生化特性,并测试了其对斑鳢、乌鳢和鲫的致病力。结果证明,斑鳢的细菌性败血症是由嗜水气单胞菌（Ａｅｒｏｍｏｎａｓｈｙｄｒｏｐｈｉｌａ）引起的     

仔猪雷极氏普罗菲登斯菌的分离鉴定及系统进化分析

为了解猪雷极氏普罗菲登斯菌（P ．rettgeri）的生物学特性、致病性及16 S rRNA基因系统进化关系,本研究从发生严重腹泻、血便的哺乳仔猪群的内脏器官中分离到1株病原菌,根据形态特征、培养特性、生化特性、16 S rRNA基因序列分析鉴定为 P ．rettgeri。小鼠攻毒试验证实该分离菌株对试验小鼠有较强致病力,哺乳仔猪回归试验可复制出与临床上相似的典型症状,并从发病死亡小鼠及哺乳仔猪中分离到攻毒菌株。系统进化分析表明,分离菌株与雷极氏普罗菲登斯菌系统进化关系最为密切,其16 S rRNA 基因序列与雷极氏普罗菲登斯菌代表菌株的同源性在97．3％～99．6％之间。药敏试验结果表明,分离菌株对头孢哌酮钠、头孢噻肟钠、头孢曲松钠、头孢唑啉、头孢呋肟、头孢吡肟、阿莫西林、链霉素、氨曲南、诺氟沙星、左氟沙星、恩诺沙星、卡那霉素、氨苄青霉素、阿米卡星、链霉素和阿米卡星等多数药物敏感。本研究首次报道了雷极氏普罗菲登斯菌可以引起哺乳仔猪严重腹泻,提示在仔猪腹泻中应注意该菌感染的诊断、监测和防控。     

一株松鼠猴奇异变形杆菌的分离与鉴定

2018年3月17日至3月19日,我园3只8周龄松鼠猴相继发生急性死亡,从死亡松鼠猴的肠道样本中分离出1株优势菌,经形态特征、培养特性观察,以及生化鉴定结果判定为奇异变形杆菌。对分离菌株进行药物敏感试验和小鼠毒力试验,表明该菌对小鼠有较强致病力;该分菌株对头孢类(头孢克洛、头孢曲松)、阿莫西林及阿米卡星表现为高度敏感。     

猪奇异变形杆菌的分离鉴定及分子生物学分析

从腹泻病猪消化道中分离得到一株细菌,对该菌进行分离纯化,革兰染色、培养特性和生化试验观察,并进行分子生物学鉴定确定该病病原;同时对相关致病因子进行PCR检测、敏试验和耐药基因检测分析。结果分离的菌株为革兰阴性,具有多形态性;生化试验结果初步证实该菌为变形杆菌。利用PCR方法进一步鉴定,并将PCR产物进行测序分析,结果该菌为奇异变形杆菌。致病因子检测结果表明,Ure C和Rsb A致病因子有关。药物敏感试验结果表明,该菌仅对氟哌酸和四环素敏感,而对卡那霉素,链霉素等药耐药,耐药基因检测表明,该菌aad AI、str B和oxa-31阳性。表明该分离菌株为奇异变形杆菌,其致病力性与Ure C和Rsb A有关,而其耐药性与aad AI、str B和oxa-31有关。     

陕西省鸡胚源性大肠杆菌的分离鉴定

从陕西关中六个种鸡场的１９８只死胚及出壳弱雏中分离出９８株大肠杆菌,平均分离率为４９．５％。通过小鸡致病力试验,筛选出６３株具有致病力的菌株,占分离菌的６４．３％。生化鉴定表明,这些致病菌均符合大肠埃希氏菌的生化特性。血清型鉴定可确定６种,其中以Ｏ１、Ｏ２、Ｏ７８为主,分别占鉴定菌的４４．４％（２８／６３）、３３．３％（２１／６３）和９．５％（６／６３）,另三种为Ｏ２２、Ｏ７５、Ｏ８９共占８．０％（５／６３）。有３株未定型,占４．８％（３／６３）。用１６种抗生素进行药敏试验,对先锋霉素Ｖ和恩诺沙星高度敏感,对羧苄青霉素、氨苄青霉素、氯霉素、卡那霉素、磺胺嘧啶、新霉素、链霉素中度敏感。     

沙打旺根腐病菌致病力的测定

通过对分离自不同地区的沙打旺根腐病菌19个菌株的致病力测定得知:不同种的根腐病菌对沙打旺的致病力不同,尖孢镰刀菌的致病力较强,茄病镰刀菌次之,串珠镰刀菌的致病力最弱;同种根腐病菌的不同菌株其致病力也有一定差异,证明沙打旺根腐病菌存在着致病力的分化.菌株的致病力与地区分布没有关系.     

沙门菌19个毒力岛标志性基因的PCR检测

建立沙门菌19个毒力岛标志性基因检测方法,了解沙门菌中毒力岛的分布情况。通过比对验证挑选出45个毒力基因作为19个毒力岛标志性基因,建立PCR检测方法,并对伤寒、肠炎、鼠伤寒及贝坎道夫沙门菌进行分布情况研究。19个毒力岛上45个标志性基因分别在伤寒、肠炎、鼠伤寒及贝坎道夫沙门菌得到验证,PCR扩增产物与预期扩增产物一致,电泳条带典型,无非特异扩增条带及杂带出现。45个标志性基因在伤寒、肠炎、鼠伤寒及贝坎道夫沙门菌检出率分别为75.56%、75.56%、66.67%和42.22%。本研究建立的45个毒力岛标志性基因检测方法具有结果准确、简单快速、费用低廉等优点,适用于沙门菌毒力岛研究及不同来源的沙门菌致病性风险评估。     

鸡大肠杆菌traT基因的扩增及TraT-DIG探针制备

以致病性Ｅ．ｃｏｌｉ的质粒为模板,用人工合成引物扩增出致病性相关的ｔｒａＴ基因核心部分;将菌株的致病性与ｔｒａＴ基因的扩增结果进行比较,强致病力菌株均扩增出ｔｒａＴ基因,无致病力菌株未扩增出ｔｒａＴ基因,约大多数中等致病力菌株亦扩增出ｔｒａＴ基因。扩增获得的ｔｒａＴ基因经纯化后标记地高辛（Ｄｉｇｏｘｉｎ,ＤＩＧ）研制出ｔｒａＴ－ＤＩＧ基因探针,该探针与鸡沙门氏菌、鸡白沙门氏菌、副伤寒沙门氏菌不发生     

Pathogenicity of avian influenza viruses isolated from wild mallard ducks and domestic turkeys

Groups of turkeys were exposed to different isolates of avian influenza virus from wild mallard ducks and domestic turkeys by the intracerebral, intravenous, intratracheal, and intra-airsac routes, and pathogenicity indices were calculated. For the intracerebral pathogenicity study, body weight was also measured. For intravenous, intratracheal, and intra-airsac pathogenicity studies, necropsy lesions were scored and serological responses were recorded. Only the intracerebral pathogenicity index and body weight gain post intracerebral infection demonstrated any differences between isolates. The other procedures failed to demonstrate any pathogenicity whatsoever. There was a correlation (R = 0.73) between intracerebral pathogenicity index and reduced weight gain postinfection. These studies suggest that growth suppression may be an objective measure of pathogenic potential of influenza viruses found to be nonpathogenic by other methods.     

不同H9N2亚型禽流感病毒株致病力的比较试验

参照NDV评价毒力的方法对1998—2008年间收集的25株H9N2AIV的致病性进行了比较研究。结果显示,25株H9N2AIV不同毒株间致病性有较大差异,大致分为3类：致病性偏强、致病性中等和致病性较弱。从中选出致病力有差异的8个毒株进行了1日龄雏鸡脑内接种指数（ICPI）、6周龄鸡静脉接种指数（IVPI）以及8周龄SPF鸡人工感染排毒试验,结果证明大部分毒株ICPI和IVPI基本上为0,排毒散毒的高峰期在攻毒后第5天到第6天。在25个毒株中,3#和12#表现出了比较高的致病性,不仅其EID50值最高（分别为10-8.8/0.2mL和10-8.8/0.2mL）、ELD50值最高（分别为10-7.9/0.2mL和10-8.7/0.2mL）,而且鸡胚平均死亡时间也最短（分别为66.5,69h）。3#、12#还出现了1日龄雏鸡脑内接种指数（分别为0.238,0.437）和6周鸡静脉内接种指数（分别为0.34,0.51）。在8周龄SPF鸡人工感染排毒试验中3#和12#毒株的排毒量大,排毒时间也明显长于其他毒株（第2～9天）。以上试验结果表明我国H9N2AIV不同毒株致病性有明显差异,呈多态性,致病性偏强的毒株造成鸡群较高的死亡率。     

The relation between pathogenicity and plaque size of Getah virus Kanagawa strain in suckling mice

The relation among biological properties, particularly pathogenicity for suckling mice, and plaque size was studied in four virus strains: Getah virus strain Kanagawa; two strains obtained by plaque cloning of the Kanagawa strain, Getah Kanagawa SP (G-K-SP) strain which forms small plaques (SP) only and strain G-K-LP which forms large plaques (LP) only; and strain Haruna which forms SP only. There were no marked differences among the four strains in serological properties, growth curves and sensitivity to pH, trypsin and temperature. Strain G-K-LP showed higher pathogenicity for suckling mice than strain G-K-SP. However, the pathogenicity of strain Haruna, which forms SP only, was as high as that of strain G-K-LP. Some of the clones in SP of strain Kanagawa kill all mice in 5 to 6 days after inoculation while the others required 9 to 11 days or longer before causing death. The present study showed that the pathogenicity of Getah viruses shortly after being isolated from the field, such as the Kanagawa strain, is different between large and small plaques, and even among small plaques, at least in suckling mice, and that the pathogenicity has no relation to plaque size.     

In vitro selective suppression of feline myeloid colony formation is attributable to molecularly cloned strain of feline leukemia virus with unique long terminal repeat

Molecularly cloned feline leukemia virus (FeLV)-clone 33 (C-33), derived from a cat with acute myelocytic leukemia (AML), was examined to assess its relation to the pathogenesis of AML and myelodysplastic syndrome (MDS). To evaluate in vitro pathogenicity of FeLV C-33, bone marrow colony-forming assay was performed on marrow cells infected with FeLV C-33 or an FeLV subgroup A strain (61E, a molecularly cloned strain with minimal pathogenicity). The myeloid colony-forming activity of feline bone marrow mononuclear cells infected with FeLV C-33 was significantly lower than that of cells infected with 61E. This suggests that FeLV C-33 has myeloid lineage-specific pathogenicity for cats, and that FeLV C-33 infection is useful as an experimental model for investigating pathogenesis of MDS and AML.     

Characterization of a velogenic Newcastle disease virus isolated from broilers in Saudi Arabia

A highly virulent Newcastle disease virus (SA84) was isolated from a large broiler operation in Saudi Arabia. The mean death time of chicken embryos given the minimum lethal dose, the pathogenicity of the isolate for 8-week-old chickens, the plaque characteristics, and the intracerebral pathogenicity index indicated that the isolate is of the viscerotropic velogenic pathotype.     

Comparison of the pathogenicity in three different Korean canine parvovirus 2 (CPV-2) isolates

Canine parvovirus type 2 (CPV-2) is a major pathogen inducing acute hemorrhagic gastroenteritis in dogs. Despite the identification of numerous CPV-2 variants (from CPV-2a to CPV-2c), the pathogenic differences among the CPV-2 variants in dogs have not been evaluated. The aim of this study was to compare the pathogenicity of CPV-2 variants (CPV-2a-I, CPV-2a-V and CPV-2b) isolated mainly from Korea. We evaluated the pathogenicity of three different CPV-2 variants, by performing clinical, hematological, serological and histopathological examinations after experimentally inoculating three types of CPV-2 variants into young puppies. We found that the overall pathogenicity of the CPV-2a variants (CPV-2a-I and 2a-V) was severer compared to the CPV-2b variant. In addition, there was no significant difference in pathogenicity between the two CPV-2a variants. Our findings indicate that there are differences in the pathogenicity of CPV-2 variants in dogs, which may be useful to understand the different pathobiology of the CPV-2 variants.