副猪嗜血杆菌血清5型间接血凝试验和间接ELISA抗体检测方法的建立

为建立副猪嗜血杆菌（HPS）的血清学诊断方法，通过探索HPS荚膜多糖产生的最适体外培养条件，提取了HPS血清5型菌株的荚膜多糖（CPS），并以之为抗原分别建立了间接血凝试验（IHA）和间接ELISA两种抗体检测方法，对其特异性、敏感性和符合率进行了比较研究。结果表明，两种检测方法的特异性良好，但ELISA的敏感性是IHA的5～10倍，二者的阳性符合率、阴性符合率和总符合率分别为79．7％、55．2％和65．3％。用这两种方法检测了320份临床送检猪血清，IHA和ELISA的阳性率分别为40％和59％。结果证实，这两种方法适用于不同实验室条件下HPS的诊断和流行病学调查。     

Establishment, validation and use of the Kielstein-Rapp-Gabrielson serotyping scheme for Haemophilus parasuis

OBJECTIVES: To produce antisera to the 15 recognised reference strains of the Kielstein-Rapp-Gabrielson (KRG) serotyping scheme for Haemophilus parasuis, validate those sera and use them to serotype 46 Australian field isolates of H parasuis. DESIGN: Antisera were produced in rabbits and validated by cross-testing with the reference strains and re-testing 15 Australian field isolates of H parasuis that had been previously serotyped in the United States of America. The validated antisera were then used to determine the serovar of 46 Australian isolates. RESULTS: Monospecific antisera were produced for 14 of the 15 KRG serovars of H parasuis. Two Australian field isolates, confirmed previously as serovars 1 and 7, were used to produce monospecific antisera for serovars 1 and 7 respectively. The antiserum for serovar 4 gave a one-way cross reaction with the antigen of serovar 14. The typing antisera correctly typed all 15 H parasuis that had been previously typed by antisera produced overseas. The 46 field isolates were shown to belong to serovars 2 (two isolates), 4 (one isolate), 5 (18 isolates), 12 (two isolates) and 13 (four isolates). The remaining 19 isolates were non-typable. CONCLUSION: Serotyping of H parasuis isolates is now available in Australia. H parasuis serovars 5 and 13 remain the predominant serovars present in Australian pigs.     

副猪嗜血杆菌分离株耐药性、血清型及RAPD基因型分析

为弄清某规模化养猪场感染和流行的副猪嗜血杆菌(HPS)菌株的耐药性、血清型及基因型,本试验自该猪场发生浆膜炎和关节炎病猪的不同组织样品中分离到6株HPS菌株,通过细菌培养特性、生化试验和PCR扩增细菌16S rRNA基因片段并测序对分离株进行鉴定;进而鉴定分离株对不同类别抗生素的耐药性;最后对分离株进行血清分型和RAPD基因分型并分析两者的相关性。结果显示,自病猪不同组织脏器中分离鉴定了6株HPS菌株,体外培养具有典型卫星生长现象;生化试验结果符合HPS反应特性;PCR均可扩增出821 bp的HPS 16S rRNA基因片段,且序列与HPS一致。药敏试验结果显示分离株对头孢菌素类、青霉素类、氨基糖苷类、大环内酯类和四环素类抗生素敏感,而对喹诺酮类、磺胺类、林可霉素类和氯霉素类抗生素产生耐药性。琼脂扩散试验结果显示HPS分离株均为血清5型;RAPD分析显示HPS分离株与15个血清型参考菌株可分为4个基因型。本试验结果为HPS的流行病学调查及防控具有一定的借鉴价值。     

Characterization of the diversity of Haemophilus parasuis field isolates by use of serotyping and genotyping

OBJECTIVE: To characterize the genetic diversity of Haemophilus parasuis field isolates with regard to serovar, herd of origin, and site of isolation. SAMPLE POPULATION: Isolates of H parasuis obtained from pigs in 15 North American herds and multi-farm systems. PROCEDURE: 98 H parasuis isolates were genotyped with the enterobacterial repetitive intergeneic consensus based-polymerase chain reaction (ERIC-PCR) technique and serotyped via agar gel precipitation test. Genomic fingerprints were analyzed and dendrograms were constructed to identify strains from the same serovar group, herd of origin, or isolation site and to evaluate the genetic variability within these categories. RESULTS: Serovar 4 (39%) and nontypeable (NT) isolates (27%) were most prevalent. Thirty-four distinct strains were identified among the 98 isolates, using a 90% similarity cutoff. Strains from serovar 4 and NT isolates had high genetic diversity (12 and 18 strains, respectively). One to 3 major clusters of prevalent strains could be identified in most of the evaluated herds. Haemophilus parasuis strains isolated from the upper respiratory tract were either serovar 3 or NT isolates. Potentially virulent strains (isolated from systemic sites) were either serovars 1, 2, 4, 5, 12, 13, or 14, or NT isolates. CONCLUSIONS AND CLINICAL RELEVANCE: Although H parasuis had high genetic diversity overall, only a few strains caused disease in these herds. The ERIC-PCR technique was more discriminative than serotyping, and a broad genetic variety was observed within particular serovar groups.     

Characterization of Haemophilus parasuis isolated from Brazilian swine through serotyping, AFLP and PFGE

Haemophilus parasuis infection in pigs is characterized by fibrinous polyserositis, arthritis and meningitis. Despite the fact that traditional diagnosis is based on herd history, clinical signs, bacterial isolation and serotyping, molecular-based methods are alternatives for species-specific tests and epidemiological studies. The aim of this study was to characterize H. parasuis field strains from different states of Brazil, employing serotyping and genotyping methods. Serotyping revealed that serovar 4 was the most prevalent (26.1%), followed by serovars 5 (17.4%), 14 (8.7%), 13 (4.4%) and 2 (4.4%), whereas 39% of the strains were considered as untypeable. AFLP with a single enzyme and PFGE were able to type all isolates tested, generating 34 and 20 different profiles, respectively, including untypeable strains. Besides the slightly higher discrimination index presented by AFLP, PFGE with Not I restriction enzyme showed a better correlation with epidemiological data, grouping strains of the same serovar, animal or farm origin. The results indicated AFLP and PFGE as valuable tools for typing H. parasuis isolates collected in Brazil.     

Development of a universal plate-agglutination test for detecting Haemophilus parasuis

Due to the serovar diversity in Haemophilus (H.) parasuis, it is difficult to develop a universal serological method for detection of this pathogen. Here, we report a universal plate-agglutination test for detecting H. parasuis. Diagnostic antisera were prepared by mixing antisera of serovars 4, 5, 12, 13 and 14 in the optimized ratio. The results of the plate-agglutination test showed that the diagnostic antisera could agglutinate with all 15 reference strains of H. parasuis and 74/75 clinical isolates. Further, the specificity of the method was validated with 22 bacterial strains from 12 related species.     

副猪嗜血杆菌间接ELISA抗体检测方法的建立

采用福尔马林灭活的副猪嗜血杆菌全菌体作为包被抗原,建立了检测副猪嗜血杆菌抗体的间接ELISA方法。经试验确定副猪嗜血杆菌全菌体的包被浓度为2·24×107CFU/孔、检测血清为1∶200稀释,同时确立了间接ELISA的最佳反应条件。该方法有很高的特异性和重复性,14个发病猪场100份血清检测结果Hps抗体阳性检出率为94%,明显高于细菌分离鉴定检测结果。     

Comparison of sampling sites and detection methods for Haemophilus parasuis

Objective To improve the isolation rate and identification procedures for Haemophilus parasuis from pig tissues. Design Thirteen sampling sites and up to three methods were used to confirm the presence of H. parasuis in pigs after experimental challenge. Procedure Colostrum‐deprived, naturally farrowed pigs were challenged intratracheally with H parasuis serovar 12 or 4. Samples taken during necropsy were either inoculated onto culture plates, processed directly for PCR or enriched prior to being processed for PCR. The recovery of H parasuis from different sampling sites and using different sampling methods was compared for each serovar. Results H parasuis was recovered from several sample sites for all serovar 12 challenged pigs, while the trachea was the only positive site for all pigs following serovar 4 challenge. The method of solid medium culture of swabs, and confirmation of the identity of cultured bacteria by PCR, resulted in 38% and 14% more positive results on a site basis for serovars 12 and 4, retrospectively, than direct PCR on the swabs. This difference was significant in the serovar 12 challenge. Conclusion Conventional culture proved to be more effective in detecting H parasuis than direct PCR or PCR on enrichment broths. For subacute (serovar 4) infections, the most successful sites for culture or direct PCR were pleural fluid, peritoneal fibrin and fluid, lung and pericardial fluid. For acute (serovar 12) infections, the best sites were lung, heart blood, affected joints and brain. The methodologies and key sampling sites identified in this study will enable improved isolation of H parasuis and aid the diagnosis of Glässer's disease.     

An indirect haemagglutination test for the detection of Vibrio fetus antibodies

Abstract

Extract

Indirect bacterial haemagglutination was first reported by Keogh et al. (1947 Keogh, E. V., North, E. A. and Warburton, M. F. 1947. Nature (Lond.), 160: 63–63.  [Google Scholar]). It depends on the adsorption of bacterial antigens to the surface of red blood cells rendering them agglutinable in the presence of homologous bacterial antibody. A comprehensive review by Neter (1956 Neter, E. 1956. Bact. Rev., 20: 166–166.  [Google Scholar]) summarizes the methods used and results achieved with various bacterial antigens. Biberstein (1955 Biberstein, E. L. 1955. Cornell Vet., 46: 144–144.  [Google Scholar]) used an adaption of Neter's method of antigen preparation in studying the antigenic relationships of Vibrio species. The objects of the present studywere to determine whether an erythrocyte adsorbable antigen could be obtained from Vibrio fetus, to compare its sensitivity with a formalinized bacterial antigen, and to study its application to the detection of antibodies in bovine vaginal mucus. The work will be described in two sections, the first dealing with the preparation and properties of sheep red cells modified with material derived :from V. fetus, and the second with the detection of antibodies in bovine vaginal mucus.     

An indirect haemagglutination test for the detection of Brucella ovis antibodies

Abstract

Extract

Surveys on perinatal infection in lambs in New Zealand have been reported and the pathology and bacteriology of the conditions described (Hartley and Boyes, 1955 Hartley, W. J. and Boyes, Betty W. 1955. Proc. N.Z. Soc. anim. Prod., 15: 120–120.  [Google Scholar], 1964 Hartley, W. J. and Boyes, Betty W. 1964. N.Z. vet J., 12: 33–33. [Taylor &; Francis Online] , [Google Scholar]; McFarlane, 1955 McFarlane, D. 1955. Proc. N.Z. Soc. anim. Prod., 15: 104–104.  [Google Scholar]; Hartley and Kater, 1964 Hartley, W. J. and Kater, Joan C. 1964. N.Z. vet. J., 12: 49–49. [Taylor &; Francis Online] , [Google Scholar]). Potentially pathogenic organisms were isolated from 58 to 288 lambs from five flocks, Clostridium septicum being isolated from five of these cases (Hartley and Boyes, 1955 Hartley, W. J. and Boyes, Betty W. 1955. Proc. N.Z. Soc. anim. Prod., 15: 120–120.  [Google Scholar]). In another survey, 5.5% of lambs born dead or dying up to 4 weeks of age died from navel infection. Clostridium septicum was isolated from 69% of 48 consecutive cases (Hartley and Boyes, 1964 Hartley, W. J. and Boyes, Betty W. 1964. N.Z. vet J., 12: 33–33. [Taylor &; Francis Online] , [Google Scholar]). McFarlane (1955 McFarlane, D. 1955. Proc. N.Z. Soc. anim. Prod., 15: 104–104.  [Google Scholar]) recorded that 7.3% of perinatal mortality was due to navel infection but no bacteriology was carried out nor was the organism suspected stated. On individual farms, up to 15% of lambs recorded died from navel ill. It should be pointed out that, in this survey, only small numbers of lambs were received from some properties.     

副猪嗜血杆菌抗体间接血凝检测方法的建立及应用

将副猪嗜血杆菌（Haemophilus parasuis，HPS）血清型4、5型分离菌株经超声波破碎处理后的产物致敏醛化红细胞，建立了检测HPS抗体的间接血凝试验方法。最适反应条件为绵羊红细胞30℃醛化5h，4、5型菌株浓缩抗原以1：8稀释致敏红细胞。免疫猪2周后检出率达89％。对15种HPS血清型阳性血清进行检测，结果均为阳性；对猪瘟病毒、口蹄疫病毒、猪圆环病毒、猪细小病毒、猪伪狂犬病病毒、猪生殖与呼吸综合征病毒、猪肺炎支原体、猪链球菌、猪肺疫巴氏杆菌、Ⅰ相支气管败血波氏杆菌及胸膜肺炎放线杆菌阳性血清进行检测，结果均为阴性。敏感性为琼脂扩散试验的16倍。对1665份猪血清进行检测，阳性率为47．1％。结果表明，该方法敏感性较高，特异性强，重复性好，可用于疫苗免疫后抗体水平的检测及副猪嗜血杆菌的流行病学调查。     

副猪嗜血杆菌ompP2基因的克隆、表达及间接ELISA抗体检测方法的建立

用PCR方法扩增副猪嗜血杆菌的外膜蛋白ompP2基因,序列测定结果表明扩增片段全长1 188bp。将扩增片段插入表达载体pET-32a,转化BL21进行诱导表达,SDS-PAGE电泳结果证实重组融合蛋白约为60 000,West-ern-blot结果表明重组表达蛋白具有免疫反应性。以纯化的重组蛋白ompP2作为抗原,建立副猪嗜血杆菌的抗体间接ELISA检测方法。通过试验确定最佳反应条件为抗原包被质量浓度4.75mg/L,4℃包被过夜,待检血清的稀释浓度为1∶40,阳性判断标准为D630大于0.383。特异性和重复性试验表明,建立的间接ELISA方法具有良好的特异性和敏感性,可用于副猪嗜血杆菌的检测。     

Development of an improved species specific PCR test for detection of Haemophilus parasuis

A PCR test for identification of Haemophilus parasuis was optimized using the 16S rDNA sequences of the 15 serotype reference strains of H. parasuis. The test was evaluated on a collection of 218 Danish field isolates as well as on 81 representatives of 27 other species, including genetically affiliated species within Pasteurellaceae. In addition, DNA preparations from 56 H. parasuis isolates from North America were included. To obtain a test that was specific for H. parasuis, a multiplex PCR using 3 different primers was developed. The PCR test produced an amplicon of approximately 1090 bp only with representatives of H. parasuis. The test was further evaluated on 55 clinical samples from 16 Danish pigs suspected for being infected with H. parasuis, showing polyserositis or septicemia at autopsy as well as on 492 nasal swabs. The test was compared with the performance of a PCR test earlier published by Oliveira et al. [Oliveira, S., Galina, L., Pijoan, C., 2001. Development of a PCR test to diagnose Haemophilus parasuis infections. J. Vet. Diagn. Invest. 13, 495-501]. The sensitivity of the present PCR test was found to be slightly lower when applied on clinical samples from diseased pigs and 10-fold lower when tested on pure cultures of H. parasuis (5CFU and 0.5CFU/PCR reaction, respectively). Addition of 1.4 x 10(5) Escherichia coli to each PCR tube did not alter the sensitivity of the tests. No difference in sensitivity of the tests was observed when tested on purified DNA. On the other hand, the present PCR test was found to be 100% species specific for H. parasuis, in contrast to the PCR test of Oliveira et al., which also tested positive for strains belonging to A. indolicus, A. porcinus, and A. minor, species commonly occurring in the upper respiratory tract. However, when the PCR test of Oliveira et al. is used on samples from systemic locations the chances for false positive results are apparently low. The present PCR test represents a rapid and reliable method for genetically based identification of H. parasuis. The high species specificity of the test makes it suitable for detection of H. parasuis in clinical samples, regardless of the presence of affiliated species and contaminating flora. As the two PCR tests differ in sensitivity and specificity, the use of both PCR tests for different purposes is a possibility.     

Comparison between Haemophilus parasuis infection in colostrums-deprived and sow-reared piglets

The aim of this study was to compare the development of Glasser's disease in sow-reared and colostrum-deprived piglets. Ninety piglets from a commercial pig farm in Spain were used. The farm was positive for Haemophilus parasuis. Fifty-two pigs were sow-reared (SR) and 38 were colostrum-deprived (CD) piglets. The animals were intratracheally inoculated with H. parasuis serovar 5 and sacrificed at 1, 2 and 3 days post-infection. To assess the development of disease, antibody titers, clinical signs, pathological lesions, microbiological isolation and PCR amplification were compared between the groups. Inoculation of SR pigs did not cause clinical signs or lesions of Glasser's disease. In SR pigs, H. parasuis isolation and specific PCR amplification from tissues showed a very low number of positive samples. In contrast, in CD pigs, inoculation resulted in the typical signs and lesions of Glasser's disease. Positive microbiological isolation and specific PCR products were obtained from the majority of the tissues tested, and no antibodies against H. parasuis were detected. The experimental infection using CD pigs describes a successful method to study this microorganism and confirms the important role that maternal antibodies play in protection against clinical signs and disease.     

Development of a PCR test to diagnose Haemophilus parasuis infections.

A polymerase chain reaction (PCR) test was developed in order to improve the accuracy and speed of diagnosis of Haemophilus parasuis, an economically important respiratory pathogen that affects swine. The gene sequence of the 16S small subunit ribosomal RNA of H. parasuis (GenBank M75065) was compared with 56 16S sequences of related bacteria, including those frequently isolated from pig tissues. Two species-specific primers were designed: HPS forward and HPS reverse. The predicted size of the amplified PCR product was 821 bp. The PCR test could detect a minimum of 102 bacteria and 0.69 pg of DNA. Thirty-one H. parasuis isolates, including 12 different serovars and 19 field isolates, were positive using the PCR test. No amplification was observed when the test was run using DNA from 15 other bacterial species commonly isolated from swine tissues. A weak band was observed when the PCR test was performed using Actinobacillus indolicus DNA as template. Clinical samples tested by PCR included tissues and swabs from 5 animals naturally infected with H. parasuis and 1 experimentally infected animal. The PCR was positive in 26 of 30 clinical samples. Four samples showed weak bands, and these results were not considered positive. Haemophilus parasuis was isolated from 18 of 30 of these samples. Tissues from specific pathogen-free (SPF) pigs and from unrelated species were negative for H. parasuis isolation and PCR. The developed PCR was successfully used in the diagnosis of H. parasuis infection, especially when compared with traditional microbiology techniques.     

副猪嗜血杆菌的实验室检测技术

副猪嗜血杆菌病发病率和死亡率较高,给养猪业造成了严重损失。为及时确诊该病,本文从细菌分离鉴定、血清学检测和分子生物学检测3个方面,对副猪嗜血杆菌实验室诊断方法的研究进展及其优缺点进行了综述。细菌分离鉴定特异性较强,但操作复杂、用时长、所需仪器多,无法满足快速检测需求;酶联免疫吸附试验(ELISA)、间接血凝试验(IHA)和补体结合试验(CF)3种血清学检测方法操作简便、快速,但特异性和敏感性不高,主要适用于早期诊断和筛查。近年来,分子生物技术快速发展,已建立了PCR、荧光定量PCR、数字PCR和环介导等温扩增(LAMP)等多种分子生物学检测方法。这些分子生物学检测方法敏感、快速、特异和稳定,其中PCR、荧光定量PCR已广泛应用于实践中,而数字PCR和LAMP检测技术尚需进一步优化。多种特异性好、灵敏度高、重复性好、检测快速的实验室检测方法的建立和改进,为副猪嗜血杆菌病检测和流行病学调查提供了有效的技术支撑。