Clonal expansion within pneumococcal serotype 6C after use of seven-valent vaccine

Streptococcus pneumoniae causes invasive infections, primarily at the extremes of life. A seven-valent conjugate vaccine (PCV7) is used to protect against invasive pneumococcal disease in children. Within three years of PCV7 introduction, we observed a fourfold increase in serotype 6C carriage, predominantly due to a single clone. We determined the whole-genome sequences of nineteen S. pneumoniae serotype 6C isolates, from both carriage (n = 15) and disease (n = 4) states, to investigate the emergence of serotype 6C in our population, focusing on a single multi-locus sequence type (MLST) clonal complex 395 (CC395). A phylogenetic network was constructed to identify different lineages, followed by analysis of variability in gene sets and sequences. Serotype 6C isolates from this single geographical site fell into four broad phylogenetically distinct lineages. Variation was seen in the 6C capsular locus and in sequences of genes encoding surface proteins. The largest clonal complex was characterised by the presence of lantibiotic synthesis locus. In our population, the 6C capsular locus has been introduced into multiple lineages by independent capsular switching events. However, rapid clonal expansion has occurred within a single MLST clonal complex. Worryingly, plasticity exists within current and potential vaccine-associated loci, a consideration for future vaccine use, target selection and design

Viral inhibition of bacterial phagocytosis by human macrophages: redundant role of CD36

Macrophages are essential to maintaining lung homoeostasis and recent work has demonstrated that influenza-infected lung macrophages downregulate their expression of the scavenger receptor CD36. This receptor has also been shown to be involved in phagocytosis of Streptococcus pneumoniae, a primary agent associated with pneumonia secondary to viral infection. The aim of this study was to investigate the role of CD36 in the effects of viral infection on macrophage phagocytic function. Human monocyte-derived macrophages (MDM) were exposed to H3N2 X31 influenza virus, M37 respiratory syncytial virus (RSV) or UV-irradiated virus. No infection of MDM was seen upon exposure to UV-irradiated virus but incubation with live X31 or M37 resulted in significant levels of viral detection by flow cytometry or RT-PCR respectively. Infection resulted in significantly diminished uptake of S. pneumoniae by MDM and significantly decreased expression of CD36 at both the cell surface and mRNA level. Concurrently, there was a significant increase in IFN? gene expression in response to infection and we observed a significant decrease in bacterial phagocytosis (p = 0.031) and CD36 gene expression (p = 0.031) by MDM cultured for 24 h in 50IU/ml IFN?. Knockdown of CD36 by siRNA resulted in decreased phagocytosis, but this was mimicked by transfection reagent alone. When MDM were incubated with CD36 blocking antibodies no effect on phagocytic ability was observed. These data indicate that autologous IFN? production by virally-infected cells can inhibit bacterial phagocytosis, but that decreased CD36 expression by these cells does not play a major role in this functional deficiency

CD1b-restricted GEM T cell responses are modulated by Mycobacterium tuberculosis mycolic acid meromycolate chains

Tuberculosis, caused by Mycobacterium tuberculosis, remains a major human pandemic. Germline-encoded mycolyl lipid-reactive (GEM) T cells are donor-unrestricted and recognize CD1b-presented mycobacterial mycolates. However, the molecular requirements governing mycolate antigenicity for the GEM T cell receptor (TCR) remain poorly understood. Here, we demonstrate CD1b expression in tuberculosis granulomas and reveal a central role for meromycolate chains in influencing GEM-TCR activity. Meromycolate fine structure influences T cell responses in TB-exposed individuals, and meromycolate alterations modulate functional responses by GEM-TCRs. Computational simulations suggest that meromycolate chain dynamics regulate mycolate head group movement, thereby modulating GEM-TCR activity. Our findings have significant implications for the design of future vaccines that target GEM T cells

A novel mouse model for checkpoint inhibitor-induced adverse events.

Immune checkpoint inhibitors have demonstrated significant efficacy in the treatment of a variety of cancers, however their therapeutic potential is limited by abstruse immune related adverse events. Currently, no robust animal model exists of checkpoint inhibitor-induced adverse events. Establishing such a model will improve our mechanistic understanding of this process, which in turn will inform design of improved therapies. We developed a mouse model to determine inflammatory toxicities in response to dual checkpoint blockade in the presence of syngeneic tumors. Mice from susceptible genetic backgrounds received intraperitoneal injections of anti-mouse PD-1 and CTLA-4 antibodies. The mice were monitored for weight loss and histologic evidence of inflammation. Blood was collected for basic metabolic panels and titers of anti-nuclear antibodies. In parallel, mice were also treated with prednisolone, which is commonly used to treat immune related adverse events among cancer patients. Among all the genetic backgrounds, B6/lpr mice treated with anti-CTLA-4 and anti-PD-1 antibodies developed more substantial hepatitis, pancreatitis, colitis, and pneumonitis characterized by organ infiltration of immune cells. Mice that developed tissue infiltration demonstrated high serum levels of glucose and high titers of anti-nuclear antibodies. Finally, while administration of prednisolone prevented the development of the inflammatory adverse events, it also abrogated the protective anti-tumor effect of the checkout inhibitors. Genetic background and treatment modalities jointly modified the inflammatory adverse events in tumor bearing mice, suggesting a complex mechanism for checkpoint inhibitor-related inflammation. Future studies will assess additional genetic susceptibility factors and will examine possible contributions from the administration of other anti-inflammatory drugs

Increase in serotype 6C pneumococcal carriage, United Kingdom

To the Editor: Streptococcus pneumoniae is a major human pathogen. In 2007, Park et al. identified a novel serotype, 6C (1), which emerged from serotype 6A. A study of children in the Netherlands who had not previously received a pneumococcal vaccine found low prevalence of this newly identified serotype before the heptavalent pneumococcal conjugate vaccine Prevnar/Prevenar (PCV7) (Wyeth, Taplow, UK) was introduced (2). Studies have shown cross-protection between vaccine serotype 6B and vaccine-related serotype 6A. However, PCV7 elicits no cross-protection against serotype 6C.The potential exists for the emergence of nonvaccine serotypes or novel clones. These serotypes and clones may be better adapted to colonize the nasopharynx, evade the human immune response, and cause disease. A recent study showed an increase in prevalence of serotype 6C pneumococci in children and a corresponding decrease in serotype 6A after introduction of PCV7 (3). We studied the underlying genetic basis for expansion of serotype 6C. Initial data from an ongoing study of pneumococcal carriage are presented.This study was reviewed and approved by the Southampton and South West Hampshire Research Ethics Committee (B) (reference 06/Q1704/105). A total of 697 nasopharyngeal swab specimens were collected from unselected (not selected by a method) children <4 years of age in the pediatric outpatient department of a large teaching hospital in the United Kingdom. Samples were obtained during October 2006–March 2007, during implementation of PCV7 in the infant immunization schedule of the United Kingdom. During October 2007–March 2008, a total of 202 pneumococci were isolated. All pneumococci were characterized by serotype and genotype.Appendix FigureAppendix Figure.Appendix Figure. Genotypes of serotype 6C pneumococci isolated from children in 2006–2007 (year 1) and 2007–2008 (year 2), United Kingdom. ST, sequence type.In the first year of this study, we identified 3 (3.1%) serotype 6C pneumococci belonging to 3 sequence types (STs): ST65, ST1714, and ST1692 (Appendix Figure). ST1714 and ST 1692 shared a common clonal complex. Only ST 65 was shared between serotype 6C and serotype 6A. In the second year, we identified 14 (13.6%) serotype 6C pneumococci belonging to 6 STs (Appendix Figure). Two of these STs, of the same ST, were from siblings. Three of them (ST1692 [n = 8], ST1714 [n = 2], and ST395 [n = 1]) were members of a common clonal complex with a predicted founder of ST395. Each of the remaining 3 STs (ST398, ST1862, and ST3460) was isolated only once. One serotype 6A isolate of ST1692 was also observed.No serotype 6C ST65 was observed in the second year. We isolated more serotype 6C pneumococci in year 2 than in year 1 (p<0.01), which was explained mostly by a large increase in ST1692 (p<0.03) (Appendix Figure). A recent study by Nunes et al. reported serotype 6C ST1692 within a clonal complex that also included ST395 and ST1714 (4), and we identified the same clonal complex in year 2 of our study.Our study showed a large increase in ST1692 in serotype 6C pneumococci during the implementation of PCV7 and an increase in serotype 6C. Depending on the extent of cross-protection between vaccine-related serotypes, introduction of conjugate vaccines could induce clearance or emergence of vaccine-related serotypes. This introduction could also contribute to their substitution with novel or existing serotypes that are better adapted to the ecologic niche. However, our data may only be relevant to carried pneumococci and not reflected in pneumococcal disease epidemiology. Nevertheless, the increase in serotype 6C pneumococci in the United Kingdom, which is supported by a similar observation in the United States (3), highlights the potential for emergence of serotypes not included in the current study and newly developed pneumococcal conjugate vaccines

Untersuchung und Optimierung der Stroemungsverhaeltnisse in Oefen beim Betrieb mit Rekuperatorbrennern Schlussbericht

SIGLETIB: RO 2407(8143) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Five winters of pneumococcal serotype replacement in UK carriage following PCV introduction

The seven-valent pneumococcal conjugate vaccine (PCV7) was added to the UK national immunisation programme in September 2006. PCV13 replaced PCV7 in April 2010. As carriage precedes disease cases this study collected carried pneumococci from children each winter from 2006/7 to 2010/11 over PCV introduction. Conventional microbiology and whole genome sequencing were utilised to characterise pneumococcal strains.Overall prevalence of pneumococcal carriage remained stable. Vaccine serotypes (VT) decreased (p < 0.0001) with concomitant increases in non-vaccine serotypes (NVT). In winter 2010/11 only one isolate of PCV7 VT was observed (6B). PCV13 unique VTs decreased between winters immediately preceding and following PCV13 introduction (p = 0.04). Significant decreases for VTs 6B, 19F, 23F (PCV7) and 6A (PCV13) and increases for NVT 21, 23B, 33F and 35F were detected. The serotype replacement was accompanied by parallel changes in genotype prevalence for associated sequence types with clonal expansion contributing to replacement. By winter 2010/11, serotype coverage of PCV7 and PCV13 was 1% and 11% respectively.VT replacement was observed for PCV7 and PCV13 serotypes. Conjugate vaccine design and use requires continuous monitoring and revision

The clonal iNKT cell repertoire in people with type 1 diabetes is characterized by a loss of clones expressing high-affinity T cell receptors

Invariant NKT (iNKT) cells in healthy people express iNKT-TCRs with widely varying affinities for CD1d, suggesting different roles for high- and low-affinity iNKT clones in immune regulation. However, the functional implications of this heterogeneity have not yet been determined. Functionally aberrant iNKT responses have been previously demonstrated in different autoimmune diseases, including human type 1 diabetes, but their relationship to changes in the iNKT clonal repertoire have not been addressed. In this study, we directly compared the clonal iNKT repertoire of people with recent onset type 1 diabetes and age- and gender-matched healthy controls with regard to iNKT-TCR affinity and cytokine production. Our results demonstrate a selective loss of clones expressing high-affinity iNKT-TCRs from the iNKT repertoire of people with type 1 diabetes. Furthermore, this bias in the clonal iNKT repertoire in type 1 diabetes was associated with increased GM-CSF, IL-4, and IL-13 cytokine secretion among Ag-stimulated low-affinity iNKT clones. Thus, qualitative changes of the clonal iNKT repertoire with the potential to affect the regulatory function of this highly conserved T cell population are already established at the early stages in type 1 diabetes. These findings may inform future rationales for the development of iNKT-based therapies aiming to restore immune tolerance in type 1 diabetes