Streptococcus pyogenes Φ1207.3 Is a Temperate Bacteriophage Carrying the Macrolide Resistance Gene Pair mef(A)-msr(D) and Capable of Lysogenizing Different Streptococci

Streptococcus pyogenes prophage phi 1207.3 (formerly Tn1207.3) carries the mef(A)-msr(D) resistance genes, responsible for type M macrolide resistance. To investigate if phi 1207.3 is a functional bacteriophage, we transferred the element from the original S. pyogenes host in a prophage-free and competence-deficient S. pneumoniae strain. Pneumococcal cultures of the phi 1207.3-carrying lysogen were treated with mitomycin C to assess if phi 1207.3 enters the lytic cycle. Mitomycin C induced a limited phage burst and a growth impairment, resulting in early entrance into the stationary phase. To determine if phi 1207.3 is able to produce mature phage particles, we prepared concentrated supernatants recovered from a mitomycin C-induced pneumococcal culture by sequential centrifugation and ultracentrifugation steps. Negative-staining transmission electron microscopy (TEM) of supernatants revealed the presence of phage particles with an icosahedral, electron-dense capsid and a long, noncontractile tail, typical of a siphovirus. Quantification of phi 1207.3 was performed by quantitative PCR (qPCR) and semiquantitatively by TEM. PCR quantified 3.34 x 10(4) and 6.06 x 10(4) excised forms of phage genome per milliliter of supernatant obtained from the untreated and mitomycin C-treated cultures, respectively. By TEM, we estimated 3.02 x 10(3) and 7.68 x 10(3) phage particles per milliliter of supernatant. The phage preparations of phi 1207.3 infected and lysogenized pneumococcal recipient strains at a frequency of 7.5 x 10(-6) lysogens/recipient but did not show sufficient lytic activity to form plaques. Phage lysogenization efficiently occurred after 30 min of contact of the phages with the recipient cells and required a minimum of 10(3) phage particles. © 2023 Santoro et al

BMC Med

BACKGROUND: Overall survival (OS) is the gold standard endpoint to assess treatment efficacy in cancer clinical trials. In metastatic breast cancer (mBC), progression-free survival (PFS) is commonly used as an intermediate endpoint. Evidence remains scarce regarding the degree of association between PFS and OS. Our study aimed to describe the individual-level association between real-world PFS (rwPFS) and OS according to first-line treatment in female patients with mBC managed in real-world setting for each BC subtype (defined by status for both hormone-receptor [HR] expression and HER2 protein expression/gene amplification). METHODS: We extracted data from the ESME mBC database (NCT03275311) which gathers deidentified data from consecutive patients managed in 18 French Comprehensive Cancer Centers. Adult women diagnosed with mBC between 2008 and 2017 were included. Endpoints (PFS, OS) were described using the Kaplan-Meier method. Individual-level associations between rwPFS and OS were estimated using the Spearman's correlation coefficient. Analyses were conducted by tumor subtype. RESULTS: 20,033 women were eligible. Median age was 60.0 years. Median follow-up duration was 62.3 months. Median rwPFS ranged from 6.0 months (95% CI 5.8-6.2) for HR-/HER2 - subtype to 13.3 months (36% CI 12.7-14.3) for HR + /HER2 + subtype. Correlation coefficients were highly variable across subtypes and first-line (L1) treatments. Among patients with HR - /HER2 - mBC, correlation coefficients ranged from 0.73 to 0.81, suggesting a strong rwPFS/OS association. For HR + /HER2 + mBC patients, the individual-level associations were weak to strong with coefficients ranging from 0.33 to 0.43 for monotherapy and from 0.67 to 0.78 for combined therapies. CONCLUSIONS: Our study provides comprehensive information on individual-level association between rwPFS and OS for L1 treatments in mBC women managed in real-life practice. Our results could be used as a basis for future research dedicated to surrogate endpoint candidates

31st Annual Meeting and Associated Programs of the Society for Immunotherapy of Cancer (SITC 2016) : part two

Background The immunological escape of tumors represents one of the main ob- stacles to the treatment of malignancies. The blockade of PD-1 or CTLA-4 receptors represented a milestone in the history of immunotherapy. However, immune checkpoint inhibitors seem to be effective in specific cohorts of patients. It has been proposed that their efficacy relies on the presence of an immunological response. Thus, we hypothesized that disruption of the PD-L1/PD-1 axis would synergize with our oncolytic vaccine platform PeptiCRAd. Methods We used murine B16OVA in vivo tumor models and flow cytometry analysis to investigate the immunological background. Results First, we found that high-burden B16OVA tumors were refractory to combination immunotherapy. However, with a more aggressive schedule, tumors with a lower burden were more susceptible to the combination of PeptiCRAd and PD-L1 blockade. The therapy signifi- cantly increased the median survival of mice (Fig. 7). Interestingly, the reduced growth of contralaterally injected B16F10 cells sug- gested the presence of a long lasting immunological memory also against non-targeted antigens. Concerning the functional state of tumor infiltrating lymphocytes (TILs), we found that all the immune therapies would enhance the percentage of activated (PD-1pos TIM- 3neg) T lymphocytes and reduce the amount of exhausted (PD-1pos TIM-3pos) cells compared to placebo. As expected, we found that PeptiCRAd monotherapy could increase the number of antigen spe- cific CD8+ T cells compared to other treatments. However, only the combination with PD-L1 blockade could significantly increase the ra- tio between activated and exhausted pentamer positive cells (p= 0.0058), suggesting that by disrupting the PD-1/PD-L1 axis we could decrease the amount of dysfunctional antigen specific T cells. We ob- served that the anatomical location deeply influenced the state of CD4+ and CD8+ T lymphocytes. In fact, TIM-3 expression was in- creased by 2 fold on TILs compared to splenic and lymphoid T cells. In the CD8+ compartment, the expression of PD-1 on the surface seemed to be restricted to the tumor micro-environment, while CD4 + T cells had a high expression of PD-1 also in lymphoid organs. Interestingly, we found that the levels of PD-1 were significantly higher on CD8+ T cells than on CD4+ T cells into the tumor micro- environment (p < 0.0001). Conclusions In conclusion, we demonstrated that the efficacy of immune check- point inhibitors might be strongly enhanced by their combination with cancer vaccines. PeptiCRAd was able to increase the number of antigen-specific T cells and PD-L1 blockade prevented their exhaus- tion, resulting in long-lasting immunological memory and increased median survival

L'edition des ARN: des messages bien caches!

National audienc

Variabilité génomique des souches de [i]Staphylococcus aureus[/i]

Staphylococcus aureus est une bactérie pathogène majeure pour l'Homme et les animaux à sang chaud, tristement célèbre pour son exceptionnelle résistance aux traitements antibiotiques et son implication dans les infections nosocomiales.S. aureus dispose d'un impressionnant arsenal de facteurs de virulence qui lui permet de coloniser la peau et les muqueuses de ces hôtes et d'y persister de façon asymptomatique. À la faveur d'une blessure ou d'une baisse de l'efficacité du système immunitaire de l'hôte, S. aureus peut déclencher un large panel d'infections opportunistes allant du simple furoncle à la septicémie mortelle.Dans l'optique de répondre aux questions que cette bactérie suscite, cet ouvrage se présente comme une synthèse abordant tous ses aspects : taxonomie, écologie, physiologie, pouvoir pathogène, épidémiologie, contrôle et prévention.Une place importante est donnée à l'antibiorésistance, aux facteurs de virulence, à leur régulation et aux infections à S. aureus chez l'homme. Les infections chez l'animal sont largement abordées de même que l'implication de S. aureus dans les toxi-infections alimentaires. Sont détaillés des approches très pragmatiques tels que les méthodes d'identification de l'espèce et de différenciation des souches de S. aureus ou les méthodes de détection dans les aliments (appliquées à la bactérie elle-même ou à ses toxines). Ses aspects sont complétés par les données les plus récentes concernant sa classification, son génome, ses besoins nutritionnels, ses stratégies de survie et de résistance aux stress et aux antibiotiques, son étiopathogénie, les sources de contamination, les éléments réglementaires.Une trentaine de spécialistes d'horizons variés (bactériologie médicale et vétérinaire, sécurité alimentaire, recherche fondamentale) se sont associés pour rédiger cet ouvrage complet, didactique et riche d'une bibliographie de plus d'un millier de références.Staphylococcus aureus s'adresse aux biologistes médicaux, aux techniciens d'analyses, aux enseignants de microbiologie et aux étudiants en BTS, IUT, Master ou préparant une formation supérieure en microbiologie

Etude de l'influence de la replication d'ADN sur la recombinaison et l'amplification dans le chromosome de Bacillus subtilis

SIGLECNRS TD 18020 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Assessing the enrichment significance of a Position Weight Matrix along a DNA sequence

absen

DNA motifs that sculpt the bacterial chromosome

During the bacterial cell cycle, the processes of chromosome replication, DNA segregation, DNA repair and cell division are coordinated by precisely defined events. Tremendous progress has been made in recent years in identifying the mechanisms that underlie these processes. A striking feature common to these processes is that non-coding DNA motifs play a central part, thus 'sculpting' the bacterial chromosome. Here, we review the roles of these motifs in the mechanisms that ensure faithful transmission of genetic information to daughter cells. We show how their chromosomal distribution is crucial for their function and how it can be analysed quantitatively. Finally, the potential roles of these motifs in bacterial chromosome evolution are discussed