Identification and characterization of novel virulence factors from the swine pathogen and zoonotic agent streptococcus suis

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Méthodes moléculaires de détection d'animaux porteurs d'actinobacillus pleuropneumoniae : comparaison et validation d'épreuves PCR

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal

Contribution of the FeoB transporter to Streptococcus suis virulence

The contribution of iron transporter systems encoded by feo genes to the pathogenic traits of streptococci is largely unknown, despite the fact that those systems are required for the full virulence of several gram-negative bacterial species. In this work, we show that the swine pathogen and zoonotic agent Streptococcus suis has a feoAB operon similar to that encoding an iron transporter system in Escherichia coli. Electrophoretic mobility assays and transcriptional analyses confirmed that the expression of S. suis feo genes is under the negative control of the ferric uptake regulator (Fur) protein. In vivo trials in mice using a feoB defective mutant strain were carried out to investigate the contribution of this gene to the virulence of S. suis. The results showed that the median lethal dose (LD50) of the mutant was approximately 10-fold higher than that of the wild-type parent strain. These data suggest that the Feo metal transporter plays a significant role in streptococcal infectious disease. This is in contrast to previous results reported for this same gene in other gram-positive bacterial species. [Int Microbiol 2009; 12(2):137-141

Phylogenomic classification and the evolution of Clonal complex 5 methicillin-resistant Staphylococcus aureus in the Western Hemisphere

Clonal complex 5 methicillin-resistant Staphylococcus aureus (CC5-MRSA) includes multiple prevalent clones that cause hospital-associated infections in the Western Hemisphere. Here, we present a phylogenomic study of these MRSA to reveal their phylogeny, spatial and temporal population structure, and the evolution of selected traits. We studied 598 genome sequences, including 409 newly generated sequences, from 11 countries in Central, North, and South America, and references from Asia and Europe. An early-branching CC5-Basal clade is well-dispersed geographically, is methicillin-susceptible and MRSA predominantly of ST5-IV such as the USA800 clone, and includes separate subclades for avian and porcine strains. In the early 1970s and early 1960s, respectively, two clades appeared that subsequently underwent major expansions in the Western Hemisphere: a CC5-I clade in South America and a CC5-II clade largely in Central and North America. The CC5-I clade includes the ST5-I Chilean/Cordobes clone, and the ST228-I South German clone as an early offshoot, but is distinct from other ST5-I clones from Europe that nest within CC5-Basal. The CC5-II clade includes divergent strains of the ST5-II USA100 clone, various other clones, and most known vancomycin-resistant strains of S. aureus, but is distinct from ST5-II strain N315 from Japan that nests within CC5-Basal. The recombination rate of CC5 was much lower than has been reported for other S. aureus genetic backgrounds, which indicates that recurrence of vancomycin resistance in CC5 is not likely due to an enhanced promiscuity. An increased number of antibiotic resistances and decreased number of toxins with distance from the CC5 tree root were observed. Of note, the expansions of the CC5-I and CC5-II clades in the Western Hemisphere were preceded by convergent gains of resistance to fluoroquinolone, macrolide, and lincosamide antibiotics, and convergent losses of the staphylococcal enterotoxin p (sep) gene from the immune evasion gene cluster of phage ΦSa3. Unique losses of surface proteins were also noted for these two clades. In summary, our study has determined the relationships of different clades and clones of CC5 and has revealed genomic changes for increased antibiotic resistance and decreased virulence associated with the expansions of these MRSA in the Western Hemisphere.Fil: Challagundla, Lavanya. University of Mississippi; Estados UnidosFil: Reyes, Jinnethe. Universidad El Bosque; ColombiaFil: Rafiqullah, Iftekhar. University of Mississippi; Estados UnidosFil: Sordelli, Daniel Oscar. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones en Microbiología y Parasitología Médica. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones en Microbiología y Parasitología Médica; ArgentinaFil: Echaniz-Aviles, Gabriela. Instituto Nacional de Salud Pùblica; MéxicoFil: Velazquez-Meza, Maria E.. Instituto Nacional de Salud Pública; MéxicoFil: Castillo-Ramírez, Santiago. Universidad Nacional Autónoma de México; MéxicoFil: Fittipaldi, Nahuel. University of Toronto; Canadá. Public Health Ontario Laboratory; CanadáFil: Feldgarden, Michael. National Institutes of Health; Estados UnidosFil: Chapman, Sinéad B.. Broad Institute of MIT and Harvard; Estados UnidosFil: Calderwood, Michael S.. Dartmouth–Hitchcock Medical Center; Estados UnidosFil: Carvajal, Lina P.. Universidad El Bosque; ColombiaFil: Rincon, Sandra. Universidad El Bosque; ColombiaFil: Blake, Hanson. University of Texas; Estados UnidosFil: Planet, Paul J.. University of Pennsylvania; Estados UnidosFil: Arias, Cesar A.. Universidad El Bosque; Colombia. University of Texas; Estados UnidosFil: Diaz, Lorena. Universidad El Bosque; ColombiaFil: Robinson, D. Ashley. University of Mississippi; Estados Unido

Whole-Genome Sequencing Applied to the Molecular Epidemiology of Shiga Toxin-Producing Escherichia coli O157:H7 in Argentina

Shiga toxin-producing Escherichia coli strains are worldwide associated with sporadic human infections and outbreaks. In this work, we report the availability of high-quality draft whole-genome sequences for 19 O157:H7 strains isolated in Argentina.Fil: Masana, Marcelo Oscar. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Tecnología de Alimentos; Argentina.Fil: Carbonari, Claudia Carolina. Instituto Nacional de Enfermedades Infecciosas-ANLIS ‘‘Dr. Carlos G. Malbrán’’. Servicio Fisiopatogenia; Argentina.Fil: Fittipaldi, Nahuel. Public Health Ontario. Toronto Laboratories; Canada. University of Toronto. Department of Laboratory Medicine and Pathobiology; Canada.Fil: Teatero, Sarah. Public Health Ontario. Toronto Laboratories; Canada.Fil: Athey, Taryn B. T. Public Health Ontario. Toronto Laboratories; Canada.Fil: Pianciola, Luis. Subsecretaría de Salud de Neuquén. Laboratorio Central; Argentina.Fil: Melano, Roberto G. Public Health Ontario. Toronto Laboratories; Canada. University of Toronto. Department of Laboratory Medicine and Pathobiology; Canada.Fil: Rivas, Marta. Instituto Nacional de Enfermedades Infecciosas-ANLIS ‘‘Dr. Carlos G. Malbrán’’. Servicio Fisiopatogenia; Argentina.Fil: Chinen, Isabel. Instituto Nacional de Enfermedades Infecciosas-ANLIS ‘‘Dr. Carlos G. Malbrán’’. Servicio Fisiopatogenia; Argentina

Mutations in the Gene Encoding the Ancillary Pilin Subunit of the Streptococcus suis srtF Cluster Result in Pili Formed by the Major Subunit Only

Pili have been shown to contribute to the virulence of different Gram-positive pathogenic species. Among other critical steps of bacterial pathogenesis, these structures participate in adherence to host cells, colonization and systemic virulence. Recently, the presence of at least four discrete gene clusters encoding putative pili has been revealed in the major swine pathogen and emerging zoonotic agent Streptococcus suis. However, pili production by this species has not yet been demonstrated. In this study, we investigated the functionality of one of these pili clusters, known as the srtF pilus cluster, by the construction of mutant strains for each of the four genes of the cluster as well as by the generation of antibodies against the putative pilin subunits. Results revealed that the S. suis serotype 2 strain P1/7, as well as several other highly virulent invasive S. suis serotype 2 isolates express pili from this cluster. However, in most cases tested, and as a result of nonsense mutations at the 5′ end of the gene encoding the minor pilin subunit (a putative adhesin), pili were formed by the major pilin subunit only. We then evaluated the role these pili play in S. suis virulence. Abolishment of the expression of srtF cluster-encoded pili did not result in impaired interactions of S. suis with porcine brain microvascular endothelial cells. Furthermore, non-piliated mutants were as virulent as the wild type strain when evaluated in a murine model of S. suis sepsis. Our results show that srtF cluster-encoded, S. suis pili are atypical compared to other Gram-positive pili. In addition, since the highly virulent strains under investigation are unlikely to produce other pili, our results suggest that pili might be dispensable for critical steps of the S. suis pathogenesis of infection

HISA big data in biomedicine and healthcare 2013 conference

Additional file 5. Biofilm formation by the S. suis serotype 2 (S2) and serotype 9 (S9) wild-type and agI/II -deficient mutant strains in the absence of porcine fibrinogen. Biofilm formation capacity was quantified after 24 h of incubation at 37 °C in the absence of porcine fibrinogen. Data represent the mean ± SEM from at least three independent experiments

Transcriptome Remodeling Contributes to Epidemic Disease Caused by the Human Pathogen Streptococcus pyogenes

For over a century, a fundamental objective in infection biology research has been to understand the molecular processes contributing to the origin and perpetuation of epidemics. Divergent hypotheses have emerged concerning the extent to which environmental events or pathogen evolution dominates in these processes. Remarkably few studies bear on this important issue. Based on population pathogenomic analysis of 1,200 Streptococcus pyogenes type emm89 infection isolates, we report that a series of horizontal gene transfer events produced a new pathogenic genotype with increased ability to cause infection, leading to an epidemic wave of disease on at least two continents. In the aggregate, these and other genetic changes substantially remodeled the transcriptomes of the evolved progeny, causing extensive differential expression of virulence genes and altered pathogen-host interaction, including enhanced immune evasion. Our findings delineate the precise molecular genetic changes that occurred and enhance our understanding of the evolutionary processes that contribute to the emergence and persistence of epidemically successful pathogen clones. The data have significant implications for understanding bacterial epidemics and for translational research efforts to blunt their detrimental effects. IMPORTANCE The confluence of studies of molecular events underlying pathogen strain emergence, evolutionary genetic processes mediating altered virulence, and epidemics is in its infancy. Although understanding these events is necessary to develop new or improved strategies to protect health, surprisingly few studies have addressed this issue, in particular, at the comprehensive population genomic level. Herein we establish that substantial remodeling of the transcriptome of the human-specific pathogen Streptococcus pyogenes by horizontal gene flow and other evolutionary genetic changes is a central factor in precipitating and perpetuating epidemic disease. The data unambiguously show that the key outcome of these molecular events is evolution of a new, more virulent pathogenic genotype. Our findings provide new understanding of epidemic disease.Peer reviewe

Does Culture Shape Our Understanding of Others’ Thoughts and Emotions? An Investigation Across 12 Countries

Q2Q2Measures of social cognition have now become central in neuropsychology, being essential for early and differential diagnoses, follow-up, and rehabilitation in a wide range of conditions. With the scientific world becoming increasingly interconnected, international neuropsychological and medical collaborations are burgeoning to tackle the global challenges that are mental health conditions. These initiatives commonly merge data across a diversity of populations and countries, while ignoring their specificity. Objective: In this context, we aimed to estimate the influence of participants’ nationality on social cognition evaluation. This issue is of particular importance as most cognitive tasks are developed in highly specific contexts, not representative of that encountered by the world’s population. Method: Through a large international study across 18 sites, neuropsychologists assessed core aspects of social cognition in 587 participants from 12 countries using traditional and widely used tasks. Results: Age, gender, and education were found to impact measures of mentalizing and emotion recognition. After controlling for these factors, differences between countries accounted for more than 20% of the variance on both measures. Importantly, it was possible to isolate participants’ nationality from potential translation issues, which classically constitute a major limitation. Conclusions: Overall, these findings highlight the need for important methodological shifts to better represent social cognition in both fundamental research and clinical practice, especially within emerging international networks and consortia.https://orcid.org/0000-0001-9422-3579https://orcid.org/0000-0001-6529-7077Revista Internacional - IndexadaA2N