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Malgarin CM, Nosach R, Novakovic P, Suleman M, Ladinig A, Detmer SE, MacPhee DJ, Harding JCS. Classification of fetal resilience to porcine reproductive and respiratory syndrome (PRRS) based on temporal viral load in late gestation maternal tissues and fetuses. Virus Res 2018; 260:151-162. [PMID: 30529234 DOI: 10.1016/j.virusres.2018.12.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Revised: 11/30/2018] [Accepted: 12/04/2018] [Indexed: 11/27/2022]
Abstract
Although porcine reproductive and respiratory syndrome virus (PRRSV) readily crosses the maternal fetal interface (MFI) in third trimester, fetal resilience varies within litters. The aim of this study was to characterize PRRSV-2 concentration in MFI and fetuses at five time points after experimental inoculation of late gestation gilts and use this information to classify potentially resistant, resilient and susceptible fetuses. The secondary objective was to verify the relationship between PRRS viral load and intrauterine growth retardation (IUGR). Three PRRSV-inoculated pregnant gilts and 1 sham-inoculated control were euthanized at five time points in days post infection (DPI; 2, 5, 8, 12, 14). The preservation status of each fetus was determined and MFI samples adjacent to the umbilical stump of each fetus, as well as serum, thymus, umbilical cord and amniotic fluid were collected. Viral load was quantified using probe-based reverse-transcriptase quantitative PCR (RT-qPCR) targeting PRRSV NVSL 97-7895 ORF7. Our result show the MFI was largely PRRSV infected by 2 DPI and virus was first detected in fetal sera and umbilical cord by 5 DPI, and in fetal thymus and amniotic fluid by 8 DPI. This indicates that PRRSV-2 quickly crossed the placenta and traveled toward the fetus via umbilical circulation within one week of the dam's inoculation. Fetal compromise was first observed on 8 DPI and increased progressively through to 14 DPI. However, several factors were associated with fetal resilience. The random forest model identified that 'viral load in fetal thymus' and duration of infection ('DPI') as the most important factors predicting fetal resilience and resistance. Moreover, IUGR fetuses had lower viral load and were less frequently compromised or dead compared to non-IUGR and average cohorts. Understanding the mechanisms of fetal resilience to PRRSV will improve selection strategies for replacement gilts.
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Affiliation(s)
- Carolina M Malgarin
- Western College of Veterinary Medicine, University of Saskatchewan, S7N 5B4, Canada.
| | - Roman Nosach
- Western College of Veterinary Medicine, University of Saskatchewan, S7N 5B4, Canada.
| | - Predrag Novakovic
- Western College of Veterinary Medicine, University of Saskatchewan, S7N 5B4, Canada.
| | - Muhammad Suleman
- Western College of Veterinary Medicine, University of Saskatchewan, S7N 5B4, Canada.
| | - Andrea Ladinig
- University of Veterinary Medicine, 1210, Vienna, Austria.
| | - Susan E Detmer
- Western College of Veterinary Medicine, University of Saskatchewan, S7N 5B4, Canada.
| | - Daniel J MacPhee
- Western College of Veterinary Medicine, University of Saskatchewan, S7N 5B4, Canada.
| | - John C S Harding
- Western College of Veterinary Medicine, University of Saskatchewan, S7N 5B4, Canada.
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Magossi G, Cernicchiaro N, Dritz S, Houser T, Woodworth J, Jones C, Trinetta V. Evaluation of Salmonella presence in selected United States feed mills. Microbiologyopen 2018; 8:e00711. [PMID: 30156384 PMCID: PMC6528605 DOI: 10.1002/mbo3.711] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Revised: 07/05/2018] [Accepted: 07/10/2018] [Indexed: 11/30/2022] Open
Abstract
Salmonella is a pathogen of public health concern. Each year, Salmonella infections cost to the food industry approximately $2.3 billion and 33% of the reported cases are associated with beef, poultry, or pork. Pathogen presence in feed mills can represent one of the many potential routes for entry and transmission into the food production chain. Nevertheless, little is known about Salmonella incidence and association with these types of environments. The objective of this study was to investigate Salmonella presence in different feed mills across the United States. Eleven facilities were selected in eight states and 12 sites were sampled within each feed mill. Samples were analyzed following the FSIS guidelines for isolation and identification of Salmonella. Positive isolates were further investigated by a PCR analysis targeting the invA gene to differentiate for Salmonella enterica. The total number of environmental samples collected was 237: 66% resulted culture positive and 13.1% were PCR positive. All sampled feed mills had at least one culture positive site and following production flow the number of positive samples decreased from ingredient receiving to final product. These preliminary results demonstrate the presence of Salmonella in selected United States feed mills and suggest their potential role as vehicle for pathogen transmission and spread into the food production chain.
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Affiliation(s)
- Gabriela Magossi
- Food Science Institute, Kansas State University, Manhattan, Kansas
| | - Natalia Cernicchiaro
- Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas
| | - Steve Dritz
- Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas
| | - Terry Houser
- Department of Animal Sciences and Industry, Kansas State University, Manhattan, Kansas
| | - Jason Woodworth
- Department of Animal Sciences and Industry, Kansas State University, Manhattan, Kansas
| | - Cassandra Jones
- Department of Animal Sciences and Industry, Kansas State University, Manhattan, Kansas
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Lalsiamthara J, Kim JH, Lee JH. Engineering of a rough auxotrophic mutant Salmonella Typhimurium for effective delivery. Oncotarget 2018; 9:25441-25457. [PMID: 29876000 PMCID: PMC5986645 DOI: 10.18632/oncotarget.25192] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Accepted: 04/05/2018] [Indexed: 11/25/2022] Open
Abstract
Live Salmonella vaccine vectors offer a remarkable platform for delivering immunogens and therapeutic molecules by mimicking natural intracellular infections; however, pre-existing anti-vector immunity can impede effective deployment. Measures to alleviate pre-existing immunity include the use of heterologous vectors, development of highly attenuated strain enabling greater payload, removal of major immunoreactive components from the vector, and/or augmentation of delivered antigens via increased presentation in antigen presenting cells. Here we report a Salmonella Typhimurium (ST) vector-JOL1800 that embodies these requisite properties. JOL1800 is a highly attenuated, auxotrophic, and O-antigen deficient rough-mutant strain. Heterologous bacterial and viral antigens were expressed and delivered using JOL1800 in mice, irrespective of the inoculation route successful inductions of the mucosal and systemic humoral responses were observed. Compared to smooth LPS vector delivery, we observed an increased fraction of delivered-antigen presenting dendritic cells and a higher frequency of delivered-antigen displayed per macrophage. Upon post-priming with JOL1800 delivery, efficacy of the delivery was minimally affected as indicated by insignificant decrease in colonization, humoral and cellular responses. Our results show that the generated vector is capable of remote antigen delivery, manifests higher antigen presentation, is Differentiating Infected from Vaccinated Animals (DIVA) capable, evades normal pre-existing immunity, and can be deployed for effective delivery.
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Affiliation(s)
- Jonathan Lalsiamthara
- College of Veterinary Medicine, Chonbuk National University, Iksan Campus, Iksan 54596, Republic of Korea
| | - Je Hyoung Kim
- College of Veterinary Medicine, Chonbuk National University, Iksan Campus, Iksan 54596, Republic of Korea
| | - John Hwa Lee
- College of Veterinary Medicine, Chonbuk National University, Iksan Campus, Iksan 54596, Republic of Korea
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4
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Diseases of the Alimentary Tract. Vet Med (Auckl) 2017. [PMCID: PMC7167529 DOI: 10.1016/b978-0-7020-5246-0.00007-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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Andres VM, Davies RH. Biosecurity Measures to Control Salmonella and Other Infectious Agents in Pig Farms: A Review. Compr Rev Food Sci Food Saf 2015. [DOI: 10.1111/1541-4337.12137] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Victor M. Andres
- Bacteriology, Animal and Plant Health Agency; New Haw Addlestone Surrey KT15 3NB UK
| | - Rob H. Davies
- Bacteriology, Animal and Plant Health Agency; New Haw Addlestone Surrey KT15 3NB UK
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De Busser EV, De Zutter L, Dewulf J, Houf K, Maes D. Salmonella control in live pigs and at slaughter. Vet J 2013; 196:20-7. [PMID: 23414643 DOI: 10.1016/j.tvjl.2013.01.002] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2012] [Revised: 11/05/2012] [Accepted: 01/07/2013] [Indexed: 02/07/2023]
Abstract
As European Union legislation sets reduction targets to lower the incidence of human salmonellosis, Member States are obliged to take effective measures to control Salmonella infection and contamination along the pig production chain. This review considers the most important control measures in the primary phase of pig production as well as during transport, lairage and along the slaughter line. Pig feed should be free of Salmonella, and contamination after feed processing must be prevented. Cleaning and disinfection procedures should be improved, although this can be complicated by the development of biofilms and the interaction between Salmonella and protozoa. Further research is required on the acid tolerance response of Salmonella strains regarding the use of organic acids in feed and/or drinking water. Vaccination of sows and piglets can be helpful but can interfere with current serosurveillance as no differentiation can yet be made between naturally infected and vaccinated animals. Fasting, transport and lairage conditions should be critically evaluated and improved. Slaughterhouses must avoid contamination and cross-contamination during all stages of the slaughter process. Scalding by steam and implementing a second singeing step after polishing are beneficial. Attention should be paid to the cleaning and disinfection procedures along the slaughter line. Carcass decontamination is a promising approach, but needs to be considered as a tool to add to good hygiene practices.
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Affiliation(s)
- Emily V De Busser
- Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B-9820 Merelbeke, Belgium.
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Bollaerts K, Aerts M, Shkedy Z, Faes C, Van der Stede Y, Beutels P, Hens N. Estimating the population prevalence and force of infection directly from antibody titres. STAT MODEL 2012. [DOI: 10.1177/1471082x12457495] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The use of threshold values in order to diagnose individual subjects as being ‘susceptible’ or ‘infected or recovered/immune’ for a specific infection is virtually always prone to false positive, false negative or inconclusive classifications. Such misclassifications might lead to biased estimates for epidemiological parameters, such as the prevalence and the force of infection. In this article, we propose to estimate these epidemiological parameters directly from antibody titres, using an underlying mixture model. The method is applied to estimate the Salmonella serological prevalence in pigs and the age-dependent force of infection using serological data on the Varicella-Zoster virus (VZV) in humans. The threshold and direct method are compared through a simulation study.
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Affiliation(s)
- K Bollaerts
- Scientific Institute of Public Health, Brussels, Belgium
| | - M Aerts
- Interuniversity Institute for Biostatistics and Statistical Bioinformatics, Hasselt University & Katholieke Universiteit Leuven, Diepenbeek, Belgium
| | - Z Shkedy
- Interuniversity Institute for Biostatistics and Statistical Bioinformatics, Hasselt University & Katholieke Universiteit Leuven, Diepenbeek, Belgium
| | - C Faes
- Interuniversity Institute for Biostatistics and Statistical Bioinformatics, Hasselt University & Katholieke Universiteit Leuven, Diepenbeek, Belgium
| | - Y Van der Stede
- Veterinary and Agrochemical Research Centre, Brussels, Belgium
| | - P Beutels
- Centre for Health Economics Research and Modeling Infectious Diseases, Centre for the Evaluation of Vaccination, Vaccine & Infectious Disease Institute, University of Antwerp, Antwerp, Belgium
| | - N Hens
- Interuniversity Institute for Biostatistics and Statistical Bioinformatics, Hasselt University & Katholieke Universiteit Leuven, Diepenbeek, Belgium
- Centre for Health Economics Research and Modeling Infectious Diseases, Centre for the Evaluation of Vaccination, Vaccine & Infectious Disease Institute, University of Antwerp, Antwerp, Belgium
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Barco L, Mancin M, Ruffa M, Saccardin C, Minorello C, Zavagnin P, Lettini A, Olsen JE, Ricci A. Application of the Random Forest Method to Analyse Epidemiological and Phenotypic Characteristics ofSalmonella4,[5],12:i:- andSalmonellaTyphimurium Strains. Zoonoses Public Health 2012; 59:505-12. [DOI: 10.1111/j.1863-2378.2012.01487.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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Abstract
The presence of one or more covariates that perfectly or almost perfectly predict the outcome of interest (which is referred to as complete or quasi-complete separation, the latter denoting the case when such perfect prediction occurs only for a subset of observations in the data) has been extensively studied in the last four decades. Since 1984, when Albert and Anderson (1984) differentiated between complete and quasi-complete separation, several authors have studied this phenomenon and tried to provide answers or ways of identifying the problem (Lesaffre and Albert, 1989; Firth, 1993; Christmann and Rousseeuw, 2001; Rousseeuw and Christmann, 2003; Allison, 2004; Zorn, 2005; Heinze, 2006). From an estimation perspective, separation leads to infinite coefficients and standard errors, which makes the algorithm collapse or give inappropriate results. As a practical matter, separation forces the analyst to choose from a number of problematic alternatives for dealing with the problem, and in the past the elimination of such problematic variables were common practice to deal with such situations. In the last decade, solutions using penalized likelihood have been proposed, but always dealing with independent binary data. Here we will propose a Bayesian solution to the problem when we deal with clustered binary data using informative priors that are supported by the data and compare it with an alternative procedure proposed by Gelman et al. (2008).
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Affiliation(s)
- José Cortiñas Abrahantes
- Interuniversity Institute for Biostatistics and Statistical Bioinformatics (I-BioStat), Center for Statistics, Hasselt University. Belgium
- European Food Safety Authority (EFSA), Parma, Italy
| | - Marc Aerts
- Interuniversity Institute for Biostatistics and Statistical Bioinformatics (I-BioStat), Center for Statistics, Hasselt University. Belgium
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Rostagno MH, Hurd HS, McKean JD. Variation of bacteriologic and serologic Salmonella enterica prevalence between cohorts within finishing swine production farms. Food Res Int 2012. [DOI: 10.1016/j.foodres.2011.01.062] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Leyman B, Boyen F, Van Parys A, Verbrugghe E, Haesebrouck F, Pasmans F. Salmonella Typhimurium LPS mutations for use in vaccines allowing differentiation of infected and vaccinated pigs. Vaccine 2011; 29:3679-85. [PMID: 21419163 DOI: 10.1016/j.vaccine.2011.03.004] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2010] [Revised: 02/14/2011] [Accepted: 03/02/2011] [Indexed: 11/25/2022]
Abstract
Contaminated pork is a major source of human salmonellosis and the serovar most frequently isolated from pigs is Salmonella Typhimurium. Vaccination could contribute greatly to controlling Salmonella infections in pigs. However, pigs vaccinated with the current vaccines cannot be discriminated from infected pigs with the LPS-based serological tests used in European Salmonella serosurveillance programmes. We therefore examined which LPS encoding genes of Salmonella Typhimurium can be deleted to allow differentiation of infected and vaccinated pigs (DIVA), without affecting the vaccine strain's protective capacity. For this purpose, deletion mutants in Salmonella strain 112910a, used as vaccine strain, were constructed in the LPS encoding genes: ΔrfbA, ΔrfaL, ΔrfaJ, ΔrfaI, ΔrfaG and ΔrfaF. Primary inoculation of BALB/c mice with the parent strain, ΔrfaL, ΔrfbA or ΔrfaJ strain but not the ΔrfaG, ΔrfaF or ΔrfaI strain protected significantly against subsequent infection with the virulent Salmonella Typhimurium strain NCTC12023. Immunization of piglets with the ΔrfaJ or ΔrfaL mutants resulted in the induction of a serological response lacking detectable antibodies against LPS. This allowed a clear differentiation between sera from pigs immunized with the ΔrfaJ or ΔrfaL strains and sera from pigs infected with their isogenic wild type strain. In conclusion, applying deletions in the rfaJ or the rfaL gene in Salmonella Typhimurium strain 112910a allows differentiation of infected and vaccinated pigs in an LPS based ELISA without reducing the strain's protective capacities in mice.
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Affiliation(s)
- Bregje Leyman
- Ghent University, Faculty of Veterinary Medicine, Department of Pathology, Bacteriology and Avian Diseases, Salisburylaan 133, 9820 Merelbeke, Belgium.
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Baptista FM, Alban L, Nielsen LR, Domingos I, Pomba C, Almeida V. Use of Herd Information for Predicting Salmonella Status in Pig Herds. Zoonoses Public Health 2010; 57 Suppl 1:49-59. [DOI: 10.1111/j.1863-2378.2010.01354.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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