The Experts below are selected from a list of 39342 Experts worldwide ranked by ideXlab platform
Virginia Aragon - One of the best experts on this subject based on the ideXlab platform.
-
Variations in association of nasal microbiota with Virulent and non-Virulent Strains of Glaesserella (Haemophilus) parasuis in weaning piglets
Veterinary Research, 2020Co-Authors: Yasser S. Mahmmod, Florencia Correa-fiz, Virginia AragonAbstract:Glaesserella (formerly Haemophilus ) parasuis causes Glässer’s disease, which results in high economic loss in the swine industry. To understand the polymicrobial interactions of G. parasuis and the nasal microbiota, the statistical association patterns of nasal colonizing bacteria with Virulent and non-Virulent Strains of G. parasuis were studied accounting for the farm management practices as potential risk factors for the occurrence of Glässer’s disease. The nasal microbiota from 51 weaned-piglets from four farms with Glässer’s disease and three farms with no respiratory diseases was previously characterized and included in this study. The presence of Virulent and/or non-Virulent G. parasuis Strains in the nasal cavities was determined in order to establish the potential association with other members of the nasal microbiota. Multivariate logistic and linear regression models were performed among the various members of nasal microbiota and G. parasuis . The multi-site production system and disease presence in the farm were both significantly associated with the presence of G. parasuis Virulent Strains in the nose of the piglets. Differential bacterial associations were observed with Virulent or non-Virulent G. parasuis . Chitinophagaceae , Corynebacteriaceae and Corynebacterium were positively associated with the Virulent G. parasuis Strains, while Enterobacteriaceae, Peptostreptococcaceae , Clostridium XI, and Escherichia/Shigella were negatively associated with Virulent G. parasuis . On the other hand, Flavobacteriaceae , Planobacterium , and Phascolarctobacterium were positively associated with the non-Virulent G. parasuis Strains, while Rikenellaceae , Enterococcaceae , Odoribacter , and Corynebacterium were negatively associated with non-Virulent G. parasuis . In conclusion, the nasal microbiota communities showed variations in the association with the G. parasuis Strains type.
-
Identification of a surface epitope specific of Virulent Strains of Haemophilus parasuis.
Veterinary microbiology, 2016Co-Authors: Florencia Correa-fiz, Nuria Galofré-milà, Mar Costa-hurtado, Virginia AragonAbstract:Haemophilus parasuis is a bacterium from the Pasteurellaceae family that comprises Strains of different degree of virulence. Non-Virulent Strains are considered components of the upper respiratory tract microbiota, while Virulent Strains can invade systemic organs and cause fibrinous polyserositis (Glasser's disease). Genomic comparison of Virulent and non-Virulent Strains led to the identification of a family of genes differentially associated to virulence, the virulence-associated trimeric autotransporters (vtaA). Monoclonal antibody 69C6 reacted with the surface of Virulent Strains and has allowed now the identification of an epitope in the C terminus of the passenger domain of the VtaAs from Virulent Strains. Protein modelling indicated that the epitope is probably exposed, although sera from pigs vaccinated with the passenger domain of VtaA9 and from convalescent animals did not react with the 69C6 epitope. Induction of antibodies against the 69C6 epitope by vaccination would allow a response targeting specifically Virulent Strains of H. parasuis.
-
biofilm formation by Virulent and non Virulent Strains of haemophilus parasuis
Veterinary Research, 2014Co-Authors: Bernardo Belloorti, Virginia Aragon, Vincent Deslandes, Yannick D N Tremblay, Josee Labrie, Kate J Howell, Alexander W Tucker, Duncan J Maskell, Mario JacquesAbstract:Haemophilus parasuis is a commensal bacterium of the upper respiratory tract of healthy pigs. It is also the etiological agent of Glasser’s disease, a systemic disease characterized by polyarthritis, fibrinous polyserositis and meningitis, which causes high morbidity and mortality in piglets. The aim of this study was to evaluate biofilm formation by well-characterized Virulent and non-Virulent Strains of H. parasuis. We observed that non-Virulent Strains isolated from the nasal cavities of healthy pigs formed significantly (p < 0.05) more biofilms than Virulent Strains isolated from lesions of pigs with Glasser’s disease. These differences were observed when biofilms were formed in microtiter plates under static conditions or formed in the presence of shear force in a drip-flow apparatus or a microfluidic system. Confocal laser scanning microscopy using different fluorescent probes on a representative subset of Strains indicated that the biofilm matrix contains poly-N-acetylglucosamine, proteins and eDNA. The biofilm matrix was highly sensitive to degradation by proteinase K. Comparison of transcriptional profiles of biofilm and planktonic cells of the non-Virulent H. parasuis F9 strain revealed a significant number of up-regulated membrane-related genes in biofilms, and genes previously identified in Actinobacillus pleuropneumoniae biofilms. Our data indicate that non-Virulent Strains of H. parasuis have the ability to form robust biofilms in contrast to Virulent, systemic Strains. Biofilm formation might therefore allow the non-Virulent Strains to colonize and persist in the upper respiratory tract of pigs. Conversely, the planktonic state of the Virulent Strains might allow them to disseminate within the host.
-
Biofilm formation by Virulent and non-Virulent Strains of Haemophilus parasuis
Veterinary research, 2014Co-Authors: Bernardo Bello-orti, Virginia Aragon, Vincent Deslandes, Yannick D N Tremblay, Josee Labrie, Kate J Howell, Alexander W Tucker, Duncan J Maskell, Mario JacquesAbstract:Haemophilus parasuis is a commensal bacterium of the upper respiratory tract of healthy pigs. It is also the etiological agent of Glasser’s disease, a systemic disease characterized by polyarthritis, fibrinous polyserositis and meningitis, which causes high morbidity and mortality in piglets. The aim of this study was to evaluate biofilm formation by well-characterized Virulent and non-Virulent Strains of H. parasuis. We observed that non-Virulent Strains isolated from the nasal cavities of healthy pigs formed significantly (p
-
Time course Haemophilus parasuis infection reveals pathological differences between Virulent and non-Virulent Strains in the respiratory tract
Veterinary Microbiology, 2014Co-Authors: Bernardo Bello-orti, Mar Costa-hurtado, Verónica Martínez-moliner, Joaquim Segalés, Virginia AragonAbstract:Abstract Haemophilus parasuis is a common inhabitant of the upper respiratory tract of pigs and the etiological agent of Glasser's disease. However, the host–pathogen interaction remains to be well understood. In this work, 33 colostrum-deprived pigs were divided in 4 groups and each group was inoculated intranasally with a different H. parasuis strain (non-Virulent Strains SW114 and F9, and Virulent Strains Nagasaki and IT29755). Animals were necropsied at different times in order to determine the location of the bacteria in the respiratory tract of the host during infection. An immunohistochemistry method was developed to detect H. parasuis in nasal turbinates, trachea and lung. Also, the co-localization of H. parasuis with macrophages or neutrophils was examined by double immunohistochemistry and double immunofluorescence. Virulent Strains showed a biofilm-like growth in nasal turbinates and trachea and were found easily in lung. Some Virulent bacteria were detected in association with macrophages and neutrophils, but also inside pneumocyte-like cells. On the other hand, non-Virulent Strains were seldom detected in nasal turbinates and trachea, where they showed a microcolony pattern. Non-Virulent Strains were essentially not detected in lung. In conclusion, this work presents data showing differential localization of H. parasuis bacteria depending on their virulence. Interestingly, the intracellular location of Virulent H. parasuis bacteria in non-phagocytic cells in lung could allow the persistence of the bacteria and constitute a virulence mechanism.
Hilde E. Smith - One of the best experts on this subject based on the ideXlab platform.
-
Detection of Virulent Strains of Streptococcus suis type 2 and highly Virulent Strains of Streptococcus suis type 1 in tonsillar specimens of pigs by PCR
Veterinary microbiology, 1999Co-Authors: Henk J. Wisselink, Frans H Reek, U. Vecht, Norbert Stockhofe-zurwieden, Mari A. Smits, Hilde E. SmithAbstract:We developed a PCR assay for the rapid and sensitive detection of Virulent Streptococcus suis type 2 and highly Virulent S. suis type 1 in tonsillar specimens from pigs. The PCR primers were based on the sequence of the gene encoding the EF-protein of Virulent S. suis type 2 Strains (MRP+EF+) and highly Virulent S. suis type 1 Strains (MRP(s)EF+) and of the EF protein of weakly Virulent S. suis type 2 Strains (MRP+EF). The latter Strains give rise to larger PCR products than the Virulent Strains of S. suis type 1 and 2. A positive control template was included in the assay to identify false negative results. The PCR was evaluated using tonsillar specimens from herds known (or suspected) to be infected and herds without an S. suis history. The results obtained with the PCR assay were compared with the results obtained with a newly developed bacteriological examination. In this bacteriological examination we were able to identify the EF-positive Strains directly in the tonsillar specimens. From the 99 tonsils examined, 48 were positive in the PCR and 51 negative. All specimens from which EF-positive S. suis Strains were isolated were also positive in the PCR assay. Three samples were positive in the PCR, but negative by bacteriological examination. The results demonstrated that the PCR is a highly specific and sensitive diagnostic tool for the detection of pigs carrying Virulent Strains of S. suis type 2 and highly Virulent Strains of type 1. Application of the assay may contribute to the control of S. suis infections.
Wei Zhang - One of the best experts on this subject based on the ideXlab platform.
-
Immunoproteomics of extracellular proteins of Chinese Virulent Strains of Streptococcus suis type 2.
Proteomics, 2007Co-Authors: Wei ZhangAbstract:Streptococcus suis type 2 (SS2) is a porcine zoonotic pathogen with worldwide distribution, and lacking suitable vaccine and Virulent maker were bottleneck to control this infection. An immunoproteomic assay was used to identify antigenic proteins from the total extracellular proteins of the Virulent Chinese SS2 strain ZY05719. The convalescent serum of a specific pathogen free (SPF) mini-pig recognized nine protein spots on PVDF membrane. Antigenic proteins on a duplicate gel, as well as those with a similar placement of extracellular proteins from another Virulent strain (HA9801) and an aVirulent strain (T15) on 2-D gels, were excised and identified by MALDI-TOF-MS. PMF of the protein spots were performed using the MASCOT server. Two proteins were found in all three Strains. Comparative proteomic analysis between the two Virulent Strains and the aVirulent strain revealed nine differential proteins, eight of which were successfully identified. Genes for six of the differentially expressed proteins were found in both Virulent Strains, and of those were present in the aVirulent stain.
Henk J. Wisselink - One of the best experts on this subject based on the ideXlab platform.
-
Detection of Virulent Strains of Streptococcus suis type 2 and highly Virulent Strains of Streptococcus suis type 1 in tonsillar specimens of pigs by PCR
Veterinary microbiology, 1999Co-Authors: Henk J. Wisselink, Frans H Reek, U. Vecht, Norbert Stockhofe-zurwieden, Mari A. Smits, Hilde E. SmithAbstract:We developed a PCR assay for the rapid and sensitive detection of Virulent Streptococcus suis type 2 and highly Virulent S. suis type 1 in tonsillar specimens from pigs. The PCR primers were based on the sequence of the gene encoding the EF-protein of Virulent S. suis type 2 Strains (MRP+EF+) and highly Virulent S. suis type 1 Strains (MRP(s)EF+) and of the EF protein of weakly Virulent S. suis type 2 Strains (MRP+EF). The latter Strains give rise to larger PCR products than the Virulent Strains of S. suis type 1 and 2. A positive control template was included in the assay to identify false negative results. The PCR was evaluated using tonsillar specimens from herds known (or suspected) to be infected and herds without an S. suis history. The results obtained with the PCR assay were compared with the results obtained with a newly developed bacteriological examination. In this bacteriological examination we were able to identify the EF-positive Strains directly in the tonsillar specimens. From the 99 tonsils examined, 48 were positive in the PCR and 51 negative. All specimens from which EF-positive S. suis Strains were isolated were also positive in the PCR assay. Three samples were positive in the PCR, but negative by bacteriological examination. The results demonstrated that the PCR is a highly specific and sensitive diagnostic tool for the detection of pigs carrying Virulent Strains of S. suis type 2 and highly Virulent Strains of type 1. Application of the assay may contribute to the control of S. suis infections.
David L Sibley - One of the best experts on this subject based on the ideXlab platform.
-
Virulent Strains of toxoplasma gondii comprise a single clonal lineage
Nature, 1992Co-Authors: David L Sibley, John C BoothroydAbstract:The protozoan Toxoplasma gondii is a prevalent parasite in wild and domestic animals worldwide, being transmitted through the food chain by carnivorous feeding and scavenging. Toxoplasma normally divides asexually to yield a haploid form that can infect virtually any vertebrate but it also has a well defined sexual cycle that occurs exclusively in cats. Toxoplasma has become important as an often fatal opportunistic pathogen in patients with AIDS, although the 15-85% of adult human populations that are chronically infected with T. gondii are typically asymptomatic. Infections in immunocompromised hosts have variable outcomes. For example, only 30 to 50% of AIDS patients that are chronically infected with the parasite develop toxoplasmic encephalitis and only about half of acute maternal infections result in congenital disease of the newborn. T. gondii Strains differ in their virulence in animals, but the extent to which different Strains are related has not been determined. Here we analyse 28 Strains from a variety of hosts on five continents and find that the ten Virulent Strains have an essentially identical genotype, whereas the nonVirulent Strains are moderately polymorphic. These data strongly suggest that Virulent Strains of T. gondii originated from a single lineage which has remained genetically homogeneous despite being globally widespread, and despite the ability of this organism to reproduce sexually.
