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Goto Y, Fukunari K, Tada S, Ichimura S, Chiba Y, Suzuki T. A multiplex real-time RT-PCR system to simultaneously diagnose 16 pathogens associated with swine respiratory disease. J Appl Microbiol 2023; 134:lxad263. [PMID: 37951290 DOI: 10.1093/jambio/lxad263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Revised: 11/01/2023] [Accepted: 11/09/2023] [Indexed: 11/13/2023]
Abstract
AIMS Swine respiratory disease (SRD) is a major disease complex in pigs that causes severe economic losses. SRD is associated with several intrinsic and extrinsic factors such as host health status, viruses, bacteria, and environmental factors. Particularly, it is known that many pathogens are associated with SRD to date, but most of the test to detect those pathogens can be normally investigated only one pathogen while taking time and labor. Therefore, it is desirable to develop rapidly and efficiently detectable methods those pathogens to minimize the damage caused by SRD. METHODS AND RESULTS We designed a multiplex real-time RT-PCR (RT-qPCR) system to diagnose simultaneously 16 pathogens, including nine viruses and seven bacteria associated with SRD, on the basis of single qPCR and RT-qPCR assays reported in previous studies. Multiplex RT-qPCR system we designed had the same ability to single RT-qPCR without significant differences in detection sensitivity for all target pathogens at minimum to maximum genomic levels. Moreover, the primers and probes used in this system had highly specificity because the sets had not been detected pathogens other than the target and its taxonomically related pathogens. Furthermore, our data demonstrated that this system would be useful to detect a causative pathogen in the diagnosis using oral fluid from healthy pigs and lung tissue from pigs with respiratory disorders collected in the field. CONCLUSIONS The rapid detection of infected animals from the herd using our system will contribute to infection control and prompt treatment in the field.
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Affiliation(s)
- Yusuke Goto
- Central Iwate Prefectural Livestock Health and Hygiene Center, Takizawa, Iwate 020-0605, Japan
| | - Kazuhiro Fukunari
- Central Iwate Prefectural Livestock Health and Hygiene Center, Takizawa, Iwate 020-0605, Japan
| | - Shigekatsu Tada
- Central Iwate Prefectural Livestock Health and Hygiene Center, Takizawa, Iwate 020-0605, Japan
| | - Satoki Ichimura
- Central Iwate Prefectural Livestock Health and Hygiene Center, Takizawa, Iwate 020-0605, Japan
| | - Yuzumi Chiba
- Central Iwate Prefectural Livestock Health and Hygiene Center, Takizawa, Iwate 020-0605, Japan
| | - Tohru Suzuki
- Division of Zoonosis Research, Sapporo Research Station, National Institute of Animal Health, NARO, Sapporo, Hokkaido 062-0045, Japan
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2
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Cao N, Tang Z, Zhang X, Li W, Li B, Tian Y, Xu D. Development and Application of a Triplex TaqMan Quantitative Real-Time PCR Assay for Simultaneous Detection of Feline Calicivirus, Feline Parvovirus, and Feline Herpesvirus 1. Front Vet Sci 2022; 8:792322. [PMID: 35211534 PMCID: PMC8861203 DOI: 10.3389/fvets.2021.792322] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2021] [Accepted: 12/15/2021] [Indexed: 11/21/2022] Open
Abstract
As companion animals, felines play an important role in human's family life, and their healthcare has attracted great attention. Viruses such as feline calicivirus (FCV), feline herpesvirus 1 (FHV-1), and feline parvovirus virus (FPV) are the most common pathogens that cause severe infectious disease in baby cats. Thus, preclinical detection and intervention of these three viruses is an effective means to prevent diseases and minimize their danger condition. In this study, a triplex TaqMan quantitative real-time polymerase chain reaction (qRT-PCR) assay was developed to detect these three viruses simultaneously. The detection limit of FPV, FCV, and FHV-1 was 5 × 101 copies/assay, which exhibited higher sensitivity (about 10- to100-fold) than conventional PCR. The coefficients of variation (CVs) of the intra-assay variability were lower than 1.86%, and that of inter-assay variability were lower than 3.19%, indicating the excellent repeatability and reproducibility of the triplex assay. Additionally, the assay showed good specificity. Finally, samples from 48 cats were analyzed using the established assay and commercial kits. As a result, the total positive rates for these viruses were 70.83 or 62.5%, respectively, which demonstrated that the developed qRT-PCR assay was more accurate than the commercial kits and could be used in clinical diagnosis.
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Affiliation(s)
- Nan Cao
- Guangdong Province Key Laboratory of Waterfowl Healthy Breeding, College of Animal Science and Technology, Zhongkai University of Agriculture and Engineering, Guangzhou, China
| | - Zhihui Tang
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Xiyu Zhang
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Wanyan Li
- Guangdong Province Key Laboratory of Waterfowl Healthy Breeding, College of Animal Science and Technology, Zhongkai University of Agriculture and Engineering, Guangzhou, China
| | - Bingxin Li
- Guangdong Province Key Laboratory of Waterfowl Healthy Breeding, College of Animal Science and Technology, Zhongkai University of Agriculture and Engineering, Guangzhou, China
| | - Yunbo Tian
- Guangdong Province Key Laboratory of Waterfowl Healthy Breeding, College of Animal Science and Technology, Zhongkai University of Agriculture and Engineering, Guangzhou, China
| | - Danning Xu
- Guangdong Province Key Laboratory of Waterfowl Healthy Breeding, College of Animal Science and Technology, Zhongkai University of Agriculture and Engineering, Guangzhou, China
- *Correspondence: Danning Xu
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3
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Sunaga F, Tsuchiaka S, Kishimoto M, Aoki H, Kakinoki M, Kure K, Okumura H, Okumura M, Okumura A, Nagai M, Omatsu T, Mizutani T. Development of a one-run real-time PCR detection system for pathogens associated with porcine respiratory diseases. J Vet Med Sci 2019; 82:217-223. [PMID: 31866601 PMCID: PMC7041981 DOI: 10.1292/jvms.19-0063] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The etiology of Porcine respiratory disease complex is complicated by infections with
multiple pathogens, and multiple infections increase the difficulty in identifying the
causal pathogen. In this present study, we developed a detection system of microbes from
porcine respiratory by using TaqMan real-time PCR (referred to as Dempo-PCR) to screen a
broad range of pathogens associated with porcine respiratory diseases in a single run. We
selected 17 porcine respiratory pathogens (Actinobacillus
pleuropneumoniae, Boldetella bronchiseptica,
Haemophilus parasuis, Pasteurella multocida,
Pasteurella multocida toxin, Streptococcus suis,
Mycoplasma hyopneumoniae, Mycoplasma hyorhinis,
Mycoplasma hyosynovie, porcine circovirus 2, pseudorabies virus,
porcine cytomegalovirus, swine influenza A virus, porcine reproductive and respiratory
virus US strain, EU strain, porcine respiratory coronavirus and porcine hemagglutinating
encephalomyelitis virus) as detection targets and designed novel specific primer-probe
sets for seven of them. In sensitivity test by using standard curves from synthesized DNA,
all primer-probe sets showed high sensitivity. However, porcine reproductive and
respiratory virus is known to have a high frequency of genetic mutations, and the primer
and probe sequences will need to be checked at a considerable frequency when performing
Dempo-PCR from field samples. A total of 30 lung samples from swine showing respiratory
symptoms on six farms were tested by the Dempo-PCR to validate the assay’s clinical
performance. As the results, 12 pathogens (5 virus and 7 bacteria) were detected and
porcine reproductive and respiratory virus US strain, Mycoplasma
hyorhinis, Haemophilus parasuis, and porcine cytomegalovirus
were detected at high frequency. These results suggest that Dempo-PCR assay can be applied
as a screening system with wide detection targets.
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Affiliation(s)
- Fujiko Sunaga
- Laboratory of Infectious Disease, School of Veterinary Medicine, Azabu University, 1-17-71 Fuchinobe, Chuo-ku, Sagamihara, Kanagawa 252-5201, Japan
| | - Shinobu Tsuchiaka
- Research and Education Center for Prevention of Global Infectious Diseases of Animals, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai, Fuchu, Tokyo 183-8509, Japan.,The United Graduate School of Veterinary Sciences, Gifu University, Yanagito, Gifu 501-1193, Japan
| | - Mai Kishimoto
- Research and Education Center for Prevention of Global Infectious Diseases of Animals, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai, Fuchu, Tokyo 183-8509, Japan
| | - Hiroshi Aoki
- Faculty of Veterinary Science, Nippon Veterinary and Life Science University, Musashino-shi, Tokyo 180-8602, Japan
| | - Mari Kakinoki
- Laboratory of Infectious Disease, School of Veterinary Medicine, Azabu University, 1-17-71 Fuchinobe, Chuo-ku, Sagamihara, Kanagawa 252-5201, Japan
| | - Katsumasa Kure
- Value Farm Consulting Co., Ltd., 1704-3 Nishi Oi, Tsukuba, Ibaraki 300-1260, Japan
| | - Hanako Okumura
- Value Farm Consulting Co., Ltd., 1704-3 Nishi Oi, Tsukuba, Ibaraki 300-1260, Japan
| | - Maho Okumura
- Drexel University Dornsife School of Public Health, Philadelphia PA 19104, USA
| | - Atsushi Okumura
- Centre for Infection and Immunity, Mailman School of Public Health, Columbia University, New York, NY 10032, USA
| | - Makoto Nagai
- Laboratory of Infectious Disease, School of Veterinary Medicine, Azabu University, 1-17-71 Fuchinobe, Chuo-ku, Sagamihara, Kanagawa 252-5201, Japan.,Research and Education Center for Prevention of Global Infectious Diseases of Animals, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai, Fuchu, Tokyo 183-8509, Japan
| | - Tsutomu Omatsu
- Research and Education Center for Prevention of Global Infectious Diseases of Animals, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai, Fuchu, Tokyo 183-8509, Japan.,The United Graduate School of Veterinary Sciences, Gifu University, Yanagito, Gifu 501-1193, Japan
| | - Tetsuya Mizutani
- Research and Education Center for Prevention of Global Infectious Diseases of Animals, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai, Fuchu, Tokyo 183-8509, Japan.,The United Graduate School of Veterinary Sciences, Gifu University, Yanagito, Gifu 501-1193, Japan
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4
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Goecke NB, Hjulsager CK, Krog JS, Skovgaard K, Larsen LE. Development of a high-throughput real-time PCR system for detection of enzootic pathogens in pigs. J Vet Diagn Invest 2019; 32:51-64. [PMID: 31752620 DOI: 10.1177/1040638719890863] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Respiratory and intestinal diseases in pigs can have significant negative influence on productivity and animal welfare. A wide range of real-time PCR (rtPCR) assays are used in our laboratory (National Veterinary Institute, Technical University of Denmark) for pathogen detection, and PCR analyses are performed on traditional rtPCR platforms in which a limited number of samples can be analyzed per day given limitations in equipment and personnel. To mitigate these restrictions, rtPCR assays have been optimized for the high-throughput rtPCR BioMark platform (Fluidigm). Using this platform, we developed a high-throughput detection system that can be used for simultaneous examination of 48 samples with detection specificity for 18 selected respiratory and enteric viral and bacterial pathogens of high importance to Danish pig production. The rtPCR assays were validated and optimized to run under the same reaction conditions using a BioMark 48.48 dynamic array (DA) integrated fluidic circuit chip, and the sensitivity and specificity were assessed by testing known positive samples. Performance of the 48.48DA was similar to traditional rtPCR analysis, and the specificity of the 48.48DA was high. Application of the high-throughput platform has resulted in a significant reduction in cost and working hours and has provided production herds with a new innovative service with the potential to facilitate the optimal choice of disease control strategies such as vaccination and treatment.
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Affiliation(s)
- Nicole B Goecke
- Division for Diagnostics & Scientific Advice, National Veterinary Institute, Technical University of Denmark, Lyngby, Denmark (Goecke, Hjulsager, Krog, Skovgaard, Larsen)
| | - Charlotte K Hjulsager
- Division for Diagnostics & Scientific Advice, National Veterinary Institute, Technical University of Denmark, Lyngby, Denmark (Goecke, Hjulsager, Krog, Skovgaard, Larsen)
| | - Jesper S Krog
- Division for Diagnostics & Scientific Advice, National Veterinary Institute, Technical University of Denmark, Lyngby, Denmark (Goecke, Hjulsager, Krog, Skovgaard, Larsen)
| | - Kerstin Skovgaard
- Division for Diagnostics & Scientific Advice, National Veterinary Institute, Technical University of Denmark, Lyngby, Denmark (Goecke, Hjulsager, Krog, Skovgaard, Larsen)
| | - Lars E Larsen
- Division for Diagnostics & Scientific Advice, National Veterinary Institute, Technical University of Denmark, Lyngby, Denmark (Goecke, Hjulsager, Krog, Skovgaard, Larsen)
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Abstract
The introduction into a naïve herd of animals sub-clinically infected with Actinobacillus pleuropneumoniae (App) is frequently the cause of clinical pleuropneumonia and the identification of such infected herds is a priority in the control of disease. Different serological tests for App have been developed and a number of these are routinely used. Some are species-specific whereas others identify more specifically the serotype/serogroup involved which requires updated information about important serotypes recovered from diseased pigs in a given area/country. Serotyping methods based on molecular techniques have been developed lately and are ready to be used by most diagnostic laboratories. When non-conclusive serological results are obtained, direct detection of App from tonsils is sometimes attempted. This review addresses different techniques and approaches used to monitor herds sub-clinically infected by this important pathogen.
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Affiliation(s)
- Marcelo Gottschalk
- Department of Pathology and Microbiology, Swine and Poultry Infectious Disease Center (CRIPA), Groupe de Recherche sur les Maladies Infectieuses du Porc (GREMIP), Faculty of Veterinary Medicine, University of Montreal, St-Hyacinthe, Québec, Canada J2S 2M2.
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6
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Serrano-Rubio LE, Tenorio-Gutiérrez V, Suárez-Güemes F, Reyes-Cortés R, Rodríguez-Mendiola M, Arias-Castro C, Godínez-Vargas D, de la Garza M. Identification of Actinobacillus pleuropneumoniae biovars 1 and 2 in pigs using a PCR assay. Mol Cell Probes 2008; 22:305-12. [DOI: 10.1016/j.mcp.2008.09.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2008] [Revised: 08/14/2008] [Accepted: 09/17/2008] [Indexed: 10/21/2022]
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7
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Burns M, Valdivia H. Modelling the limit of detection in real-time quantitative PCR. Eur Food Res Technol 2007. [DOI: 10.1007/s00217-007-0683-z] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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8
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Selkirk JV, Nottebaum LM, Lee J, Yang W, Foster AC, Lechner SM. Identification of differential melanocortin 4 receptor agonist profiles at natively expressed receptors in rat cortical astrocytes and recombinantly expressed receptors in human embryonic kidney cells. Neuropharmacology 2006; 52:459-66. [PMID: 17095023 DOI: 10.1016/j.neuropharm.2006.08.015] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2006] [Revised: 08/01/2006] [Accepted: 08/02/2006] [Indexed: 11/25/2022]
Abstract
Using cAMP accumulation as a functional readout, we pharmacologically characterized the response of native melanocortin receptors in cultured rat astrocytes, and found this response to be mediated by the melanocortin 4 receptor (MC4R). Melancortin agonists stimulate cAMP in a concentration-dependent manner in both astrocytes and human embryonic kidney cells recombinantly expressing rat MC4R (HEK-rMC4R), however, the relative potency and intrinsic activity of both small molecule and peptide agonists are reduced in the native system. As such, the small molecules THIQ, NBI-702 and MB243 display 43, 30 and 18% of the maximal response elicited by alpha-MSH in astrocytes. Likewise, the peptides MTII and ACTH display 55 and 72% of the maximal response elicited by alpha-MSH in these cells. In contrast, all of these compounds elicit full agonist responses with similar intrinsic activity to alpha-MSH in HEK-rMC4R cells. MC4R mRNA was detected in astrocytes, however radioligand binding experiments failed to detect measurable MC4R in astrocyte membranes, in contrast to membranes from HEK-rMC4R cells that display a binding site density of 18.1+/-1.5 fmol/mg. We propose that the divergent observations in functional activity between the cell types reflect differences in receptor expression and that caution should be exercised when interpreting agonist activity in over-expression systems for the purposes of drug discovery.
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MESH Headings
- Animals
- Animals, Newborn
- Astrocytes
- Binding Sites/drug effects
- Cells, Cultured
- Cerebral Cortex/cytology
- Cyclic AMP/metabolism
- Cyclic AMP Response Element-Binding Protein/metabolism
- Dose-Response Relationship, Drug
- Embryo, Mammalian
- Gene Expression Regulation/drug effects
- Gene Expression Regulation/physiology
- Hormones/pharmacology
- Humans
- Inhibitory Concentration 50
- Kidney
- Protein Binding/drug effects
- Rats
- Receptor, Melanocortin, Type 4/agonists
- Receptor, Melanocortin, Type 4/genetics
- Receptor, Melanocortin, Type 4/metabolism
- Time Factors
- alpha-MSH/pharmacology
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Affiliation(s)
- J V Selkirk
- Department of Neuroscience, Neurocrine Biosciences Inc., 12790 El Camino Real, San Diego, CA 92130, USA.
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9
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McMillen L, Fordyce G, Doogan VJ, Lew AE. Comparison of culture and a novel 5' Taq nuclease assay for direct detection of Campylobacter fetus subsp. venerealis in clinical specimens from cattle. J Clin Microbiol 2006; 44:938-45. [PMID: 16517880 PMCID: PMC1393111 DOI: 10.1128/jcm.44.3.938-945.2006] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
A Campylobacter fetus subsp. venerealis-specific 5' Taq nuclease PCR assay using a 3' minor groove binder-DNA probe (TaqMan MGB) was developed based on a subspecies-specific fragment of unknown identity (S. Hum, K. Quinn, J. Brunner, and S. L. On, Aust. Vet. J. 75:827-831, 1997). The assay specifically detected four C. fetus subsp. venerealis strains with no observed cross-reaction with C. fetus subsp. fetus-related Campylobacter species or other bovine venereal microflora. The 5' Taq nuclease assay detected approximately one single cell compared to 100 and 10 cells in the conventional PCR assay and 2,500 and 25,000 cells from selective culture from inoculated smegma and mucus, respectively. The respective detection limits following the enrichments from smegma and mucus were 5,000 and 50 cells/inoculum for the conventional PCR compared to 500 and 50 cells/inoculum for the 5' Taq nuclease assay. Field sampling confirmed the sensitivity and the specificity of the 5' Taq nuclease assay by detecting an additional 40 bulls that were not detected by culture. Urine-inoculated samples demonstrated comparable detection of C. fetus subsp. venerealis by both culture and the 5' Taq nuclease assay; however, urine was found to be less effective than smegma for bull sampling. Three infected bulls were tested repetitively to compare sampling tools, and the bull rasper proved to be the most suitable, as evidenced by the improved ease of specimen collection and the consistent detection of higher levels of C. fetus subsp. venerealis. The 5' Taq nuclease assay demonstrates a statistically significant association with culture (chi2 = 29.8; P < 0.001) and significant improvements for the detection of C. fetus subsp. venerealis-infected animals from crude clinical extracts following prolonged transport.
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Affiliation(s)
- Lyle McMillen
- Queensland Department of Primary Industries and Fisheries, c/o Animal Research Institute, Locked Mail Bag No. 4, Moorooka, 4105 QLD, Australia.
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10
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Grønbaek LM, Angen O, Vigre H, Olsen SN. Evaluation of a nested PCR test and bacterial culture of swabs from the nasal passages and from abscesses in relation to diagnosis of Streptococcus equi infection (strangles). Equine Vet J 2006; 38:59-63. [PMID: 16411588 DOI: 10.2746/042516406775374324] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
REASONS FOR PERFORMING STUDY Streptococcus equi is the cause of strangles in horses. To improve diagnostic sensitivity, development and evaluation of DNA-based methods are necessary. OBJECTIVES To evaluate diagnostic methods and observe the pattern of bacterial shedding during natural outbreaks. METHODS Two herds with natural outbreaks of strangles were visited over a period of 15 weeks and 323 samples originating from 35 horses investigated. The diagnostic use of a nested PCR test was evaluated using a collection of 165 isolates of Lancefield group C streptococci (species specificity) and swabs from nasal passages or from abscesses from horses infected with S. equi (diagnostic sensitivity). RESULTS All 45 S. equi isolates tested positive in the nested PCR, whereas no amplicon was formed when testing the other 120 Lancefield group C isolates. A total of 43 samples were collected from 11 horses showing clinical signs of strangles during the study period. The diagnostic sensitivity for PCR test was 45% and 80% for samples from the nasal passages and abscesses, respectively; the corresponding diagnostic sensitivity for cultivation was 18% and 20%. The diagnostic sensitivity was significantly higher for PCR than for bacterial cultivation. Furthermore, the shedding of S. equi in 2 infected horse populations was evaluated. An intermittent shedding period of S. equi of up to 15 weeks was recorded in this part of the study. It was also shown that shedding of S. equi occurred both from horses with and without clinical signs. CONCLUSIONS AND POTENTIAL RELEVANCE The nested PCR test represents a species-specific and -sensitive method for diagnosis of S. equi from clinical samples. It may, however, be desirable in future to develop detection methods with high diagnostic sensitivity and specificity without the potential problems inherent in nested PCR.
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Affiliation(s)
- L Møller Grønbaek
- Danish Institute for Food and Veterinary Research, Bülowsvej 27, DK- Copenhagen V, Denmark
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11
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Coker PR, Smith KL, Fellows PF, Rybachuck G, Kousoulas KG, Hugh-Jones ME. Bacillus anthracis virulence in Guinea pigs vaccinated with anthrax vaccine adsorbed is linked to plasmid quantities and clonality. J Clin Microbiol 2003; 41:1212-8. [PMID: 12624053 PMCID: PMC150325 DOI: 10.1128/jcm.41.3.1212-1218.2003] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacillus anthracis is a bacterial pathogen of great importance, both historically and in the present. This study presents data collected from several investigations and indicates that B. anthracis virulence is associated with the clonality and virulence of plasmids pXO1 and pXO2. Guinea pigs vaccinated with Anthrax Vaccine Adsorbed were challenged with 20 B. anthracis isolates representative of worldwide genetic diversity. These same isolates were characterized with respect to plasmid copy number by using a novel method of quantitative PCR developed for rapid and efficient detection of B. anthracis from environmental samples. We found that the copy numbers for both pXO1 and pXO2 differed from those in previously published reports. By combining the data on survival, plasmid copy numbers, and clonality, we developed a model predicting virulence. This model was validated by using a randomly chosen set of 12 additional B. anthracis isolates. Results from this study will be helpful in future efforts to elucidate the basis for variation in the virulence of this important pathogen.
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Affiliation(s)
- Pamala R Coker
- Department of Pathobiological Sciences. Division of Biotechnology and Molecular Medicine, School of Veterinary Medicine, Louisiana State University, Baton Rouge, Louisiana 70803, USA.
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12
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Lindecrona RH, Jensen TK, Andersen PH, Møller K. Application of a 5' nuclease assay for detection of Lawsonia intracellularis in fecal samples from pigs. J Clin Microbiol 2002; 40:984-7. [PMID: 11880427 PMCID: PMC120237 DOI: 10.1128/jcm.40.3.984-987.2002] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A 5' nuclease assay was developed to detect Lawsonia intracellularis in porcine fecal samples. The specific probe and primers were chosen by using the 16S ribosomal DNA gene as a target. The 5' nuclease assay was used with a total of 204 clinical samples, and the results were compared to those of immunohistochemistry (IM) on ileal sections of the same animals. There was 91% agreement between the results of IM and the 5' nuclease assay. In the 5' nuclease assay, 111 (54%) of the pigs tested positive for L. intracellularis infection, with a mean cycle threshold (Ct) value of 27.2, whereas 98 (48%) of the pigs tested positive by IM. On average, the Ct and DeltaRn values for the positive samples were 27.2 (standard deviation [SD], 3.7) and 1.6 (SD, 0.7), respectively. A Ct value of 27.2 corresponds to a fecal excretion of approximately 10(7) L. intracellularis cells per g of feces. Furthermore, a total of 40 fecal samples derived from a herd known to be free from infection with L. intracellularis all tested negative, with a Ct value of 40. By using a Ct value of 36 as the cutoff limit, the detection limit of the assay was 1 L. intracellularis cell per PCR tube. In conclusion, the 5' nuclease assay that has been developed represents an applicable fast method for detection of L. intracellularis in fecal samples, with a sensitivity and specificity comparable to those of IM.
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Affiliation(s)
- R H Lindecrona
- Danish Veterinary Laboratory, DK-1790 Copenhagen V, Denmark.
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