Interactions entre Streptococcus suis sérotype 2 et Haemophilus parasuis avec des cellules porcines lors des co-infections bactériennes

Streptococcus suis et Haemophilus parasuis sont des colonisateurs des voies respiratoires supérieures du porc. Ils sont toutefois les causes les plus importantes de mortalité dans les élevages à travers le monde puisqu’ils entrainent des maladies inflammatoires telles les septicémies, l’arthrite, la méningite et la pneumonie chez les porcelets suite au sevrage. Puisqu’ils empruntent la même route d’infection, produisent des maladies inflammatoires similaires et colonisent une majorité des animaux et compte tenu que les infections mixtes sont considérées comme étant la principale cause de maladie dans les animaux d’élevage, des interactions entre ces deux agents pourraient exister. En vue d’explorer les interactions entre S. suis sérotype 2 et H. parasuis de différents niveaux de virulence et leurs interactions avec les cellules porcines lors des premières étapes de l’infection, des cellules épithéliales de la trachée et des macrophages alvéolaires porcins primaires ont été infectés in vitro avec ces deux agents. Il a été possible d’observer qu’une souche peu virulente s’associe davantage aux cellules de l’hôte qu’une souche virulente, en induisant aussi généralement une plus forte réponse inflammatoire. Bien qu’il s’associe autant que la souche virulente de H. parasuis aux cellules épithéliales, S. suis induit une réponse inflammatoire généralement plus faible que H. parasuis. Contrairement à ce qui était attendu, les interactions entre S. suis et H. parasuis semblent limitées lors des premières étapes d’infection.Streptococcus suis and Haemophilus parasuis are colonizers of the upper respiratory tract of healty pigs. However, they are also the most important cause of mortality in pig farms around the world by causing inflammatory diseases such as septicemia, arthritis, meningitis and pneumonia among weaned piglets. They use the same route of infection, cause similar inflammatory diseases and colonize a majority of animals. Because mixed infections are considered as the primary cause of disease in livestock, interactions between S. suis and H. parasuis could occur. In order to investigate the interactions between S. suis serotype 2 and H. parasuis of different level of virulence and their interactions with cells during the first steps of infection, tracheal epithelial cells and primary alveolar macrophages were infected in vitro with those bacteria. It has been possible to observe that a low virulent H. parasuis strain adheres more to host cells than the virulent strain, and induces a stronger inflammatory response. Although it adheres as much as the virulent H. parasuis strain, S. suis serotype 2 induces a lower inflammatory response then H. parasuis. Contrary to what we expected, the interactions between S. suis serotype 2 and H. parasuis seem, in general, limited during the first steps of the infection

The Secretome of <em>Vibrio cholerae</em>

Vibrio cholerae is a facultative human pathogen responsible for the cholera disease which infects millions of people worldwide each year. V. cholerae is a natural inhabitant of aquatic environments and the infection usually occurs after ingestion of contaminated water or food. The virulence factors of V. cholerae have been extensively studied in the last decades and include the cholera toxin and the coregulated pilus. Most of the virulence factors of V. cholerae belong to the secretome, which corresponds to all the molecules secreted in the extracellular environment such as proteins, exopolysaccharides, extracellular DNA or membrane vesicles. In this chapter, we review the current knowledge of the secretome of V. cholerae and its role in virulence, colonization and resistance. In the first section, we focus on the proteins secreted through conventional secretion systems. The second and third sections emphasize on the membrane vesicles and on the secretome associated with biofilms

Limited Interactions between Streptococcus Suis and Haemophilus Parasuis in In Vitro Co-Infection Studies

Streptococcus suis and Haemophilus parasuis are normal inhabitants of the porcine upper respiratory tract but are also among the most frequent causes of disease in weaned piglets worldwide, causing inflammatory diseases such as septicemia, meningitis and pneumonia. Using an in vitro model of infection with tracheal epithelial cells or primary alveolar macrophages (PAMs), it was possible to determine the interaction between S. suis serotype 2 and H. parasuis strains with different level of virulence. Within H. parasuis strains, the low-virulence F9 strain showed higher adhesion levels to respiratory epithelial cells and greater association levels to PAMs than the high-virulence Nagasaki strain. Accordingly, the low-virulence F9 strain induced, in general, higher levels of pro-inflammatory cytokines than the virulent Nagasaki strain from both cell types. In general, S. suis adhesion levels to respiratory epithelial cells were similar to H. parasuis Nagasaki strain. Yet, S. suis strains induced a significantly lower level of pro-inflammatory cytokine expression from epithelial cells and PAMs than those observed with both H. parasuis strains. Finally, this study has shown that, overall and under the conditions used in the present study, S. suis and H. parasuis have limited in vitro interactions between them and use probably different host receptors, regardless to their level of virulence.info:eu-repo/semantics/publishedVersio

Limited Interactions between Streptococcus Suis and Haemophilus Parasuis in In Vitro Co-Infection Studies

Streptococcus suis and Haemophilus parasuis are normal inhabitants of the porcine upper respiratory tract but are also among the most frequent causes of disease in weaned piglets worldwide, causing inflammatory diseases such as septicemia, meningitis and pneumonia. Using an in vitro model of infection with tracheal epithelial cells or primary alveolar macrophages (PAMs), it was possible to determine the interaction between S. suis serotype 2 and H. parasuis strains with different level of virulence. Within H. parasuis strains, the low-virulence F9 strain showed higher adhesion levels to respiratory epithelial cells and greater association levels to PAMs than the high-virulence Nagasaki strain. Accordingly, the low-virulence F9 strain induced, in general, higher levels of pro-inflammatory cytokines than the virulent Nagasaki strain from both cell types. In general, S. suis adhesion levels to respiratory epithelial cells were similar to H. parasuis Nagasaki strain. Yet, S. suis strains induced a significantly lower level of pro-inflammatory cytokine expression from epithelial cells and PAMs than those observed with both H. parasuis strains. Finally, this study has shown that, overall and under the conditions used in the present study, S. suis and H. parasuis have limited in vitro interactions between them and use probably different host receptors, regardless to their level of virulence

The Influence of Behavioral, Social, and Environmental Factors on Reproducibility and Replicability in Aquatic Animal Models

The publication of reproducible, replicable, and translatable data in studies utilizing animal models is a scientific, practical, and ethical necessity. This requires careful planning and execution of experiments and accurate reporting of results. Recognition that numerous developmental, environmental, and test-related factors can affect experimental outcomes is essential for a quality study design. Factors commonly considered when designing studies utilizing aquatic animal species include strain, sex, or age of the animal; water quality; temperature; and acoustic and light conditions. However, in the aquatic environment, it is equally important to consider normal species behavior, group dynamics, stocking density, and environmental complexity, including tank design and structural enrichment. Here, we will outline normal species and social behavior of 2 commonly used aquatic species: zebrafish (Danio rerio) and Xenopus (X. laevis and X. tropicalis). We also provide examples as to how these behaviors and the complexity of the tank environment can influence research results and provide general recommendations to assist with improvement of reproducibility and replicability, particularly as it pertains to behavior and environmental complexity, when utilizing these popular aquatic models. © The Author(s) 2020. Published by Oxford University Press on behalf of the National Academies of Sciences, Engineering, and Medicine. All rights reserved.A.V.K. research was supported by the Russian Science Foundation grant 19-15-00053. He is the Chair of the International Zebrafish Neuroscience Research Consortium (ZNRC). This collaboration was supported, in part, through the NIH/NCI Cancer Center Support Grant P30 CA008748. The authors would like to thank Gregory Paull for sharing his photographs and insight into the natural habitat of zebrafish in Bangladesh

Recruitment of Factor H to the Streptococcus suis Cell Surface is Multifactorial

Streptococcus suis is an important bacterial swine pathogen and a zoonotic agent. Recently, two surface proteins of S. suis, Fhb and Fhbp, have been described for their capacity to bind factor H—a soluble complement regulatory protein that protects host cells from complement-mediated damages. Results obtained in this study showed an important role of host factor H in the adhesion of S. suis to epithelial and endothelial cells. Both Fhb and Fhbp play, to a certain extent, a role in such increased factor H-dependent adhesion. The capsular polysaccharide (CPS) of S. suis, independently of the presence of its sialic acid moiety, was also shown to be involved in the recruitment of factor H. However, a triple mutant lacking Fhb, Fhbp and CPS was still able to recruit factor H resulting in the degradation of C3b in the presence of factor I. In the presence of complement factors, the double mutant lacking Fhb and Fhbp was similarly phagocytosed by human macrophages and killed by pig blood when compared to the wild-type strain. In conclusion, this study suggests that recruitment of factor H to the S. suis cell surface is multifactorial and redundant

Plasticizer endocrine disruption: Highlighting developmental and reproductive effects in mammals and non-mammalian aquatic species

AbstractDue to their versatility, robustness, and low production costs, plastics are used in a wide variety of applications. Plasticizers are mixed with polymers to increase flexibility of plastics. However, plasticizers are not covalently bound to plastics, and thus leach from products into the environment. Several studies have reported that two common plasticizers, bisphenol A (BPA) and phthalates, induce adverse health effects in vertebrates; however few studies have addressed their toxicity to non-mammalian species. The aim of this review is to compare the effects of plasticizers in animals, with a focus on aquatic species. In summary, we identified three main chains of events that occur in animals exposed to BPA and phthalates. Firstly, plasticizers affect development by altering both the thyroid hormone and growth hormone axes. Secondly, these chemicals interfere with reproduction by decreasing cholesterol transport through the mitochondrial membrane, leading to reduced steroidogenesis. Lastly, exposure to plasticizers leads to the activation of peroxisome proliferator-activated receptors, the increase of fatty acid oxidation, and the reduction in the ability to cope with the augmented oxidative stress leading to reproductive organ malformations, reproductive defects, and decreased fertility

Flagella-dependent inhibition of biofilm formation by sub-inhibitory concentration of polymyxin B in Vibrio cholerae.

Biofilm formation is a common strategy used by bacteria in order to survive and persist in the environment. In Vibrio cholerae (V. cholerae), a Gram-negative pathogen responsible for the cholera disease, biofilm-like aggregates are important for the pathogenesis and disease transmission. Biofilm formation is initiated by the attachment of the bacteria to a surface, followed by maturation stages involving the formation of a biofilm matrix. In V. cholerae, flagella are essential for the initial step of biofilm formation, allowing the bacteria to swim and to detect a surface. In this study, we explored the effect of polymyxin B (PmB), a cationic bacterial antimicrobial peptide, on biofilm formation in pathogenic V. cholerae strains belonging to the O1 and O139 serotypes. We found that sub-inhibitory concentration of PmB induces a reduction of the biofilm formation by V. cholerae O1 and O139. Experiment on preformed biofilm demonstrated that the biofilm formation inhibition occurs at the initial step of biofilm formation, where the flagella are essential. We further characterize the effect of PmB on V. cholerae flagellation. Our results demonstrate that the flagellin expression is not reduced in presence of sub-inhibitory concentration of PmB. However, a decrease of the abundance of flagellin associated with the bacterial cells together with an increase in the secretome was observed. Electron microscopy observations also suggest that the abundance of aflagellated bacteria increases upon PmB supplementation. Finally, in agreement with the effect on the flagellation, a reduction of the bacterial motility is observed. Altogether, our results suggest that the PmB affect V. cholerae flagella resulting in a decrease of the motility and a compromised ability to form biofilm

Limited Interactions between Streptococcus Suis and Haemophilus Parasuis in In Vitro Co-Infection Studies

Streptococcus suis and Haemophilus parasuis are normal inhabitants of the porcine upper respiratory tract but are also among the most frequent causes of disease in weaned piglets worldwide, causing inflammatory diseases such as septicemia, meningitis and pneumonia. Using an in vitro model of infection with tracheal epithelial cells or primary alveolar macrophages (PAMs), it was possible to determine the interaction between S. suis serotype 2 and H. parasuis strains with different level of virulence. Within H. parasuis strains, the low-virulence F9 strain showed higher adhesion levels to respiratory epithelial cells and greater association levels to PAMs than the high-virulence Nagasaki strain. Accordingly, the low-virulence F9 strain induced, in general, higher levels of pro-inflammatory cytokines than the virulent Nagasaki strain from both cell types. In general, S. suis adhesion levels to respiratory epithelial cells were similar to H. parasuis Nagasaki strain. Yet, S. suis strains induced a significantly lower level of pro-inflammatory cytokine expression from epithelial cells and PAMs than those observed with both H. parasuis strains. Finally, this study has shown that, overall and under the conditions used in the present study, S. suis and H. parasuis have limited in vitro interactions between them and use probably different host receptors, regardless to their level of virulence