GNA2132 is a Neisseria meningitidis antigen of unknown function, discovered by reverse vaccinology, which has been shown to induce bactericidal antibodies in animal models. Here we show that this antigen induces protective immunity in humans and it is recognized by sera of patients after meningococcal disease. The protein binds heparin in vitro through an Arg-rich region and this property correlates with increased survival of the unencapsulated bacterium in human serum. Furthermore, two proteases, the meningococcal NalP and human lactoferrin, cleave the protein upstream and downstream from the Arg-rich region, respectively. We conclude that GNA2132 is an important protective antigen of N. meningitidis and we propose to rename it, N eisserial H eparin B inding A ntigen (NHBA).

Background. Pneumococcal serotypes are represented by a varying number of clonal lineages with different genetic contents, potentially affecting invasiveness. However, genetic variation within the same genetic lineage may be larger than anticipated.Methods. A total of 715 invasive and carriage isolates from children in the same region and during the same period were compared using pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing. Bacterial genome sequencing, functional assays, and in vivo virulence mice studies were performed.Results. Clonal types of the same serotype but also intraclonal variants within clonal complexes (CCs) showed differences in invasive-disease potential. CC138, a common CC, was divided into several PFGE patterns, partly explained by number, location, and type of temperate bacteriophages. Whole-genome sequencing of 4 CC138 isolates representing PFGE clones with different invasive-disease potentials revealed intraclonal sequence variations of the virulence-associated proteins pneumococcal surface protein A (PspA) and pneumococcal choline-binding protein C (PspC). A carrier isolate lacking PcpA exhibited decreased virulence in mice, and there was a differential binding of human factor H, depending on invasiveness.Conclusions. Pneumococcal clonal types but also intraclonal variants exhibited different invasive-disease potentials in children. Intraclonal variants, reflecting different prophage contents, showed differences in major surface antigens. This suggests ongoing immune selection, such as that due to PspC-mediated complement resistance through varied human factor H binding, that may affect invasiveness in children.

SummaryThe Oca (Oligomeric coiled-coil adhesin) family is a subgroup of the bacterial trimeric autotransporter adhesins, which includes structurally related proteins, such as YadA of Yersinia enterocolitica and NadA of Neisseria meningitidis. In this study, we searched in silico for novel members of this family in bacterial genomes and identified HadA (Haemophilus adhesin A), a trimeric autotransporter expressed only by Haemophilus influenzae biogroup aegyptius causing Brazilian purpuric fever (BPF), a fulminant septicemic disease of children. By comparative genomics and sequence analysis we predicted that the hadA gene is harboured on a mobile genetic element unique to BPF isolates. Biological analysis of HadA in the native background was limited because this organism is not amenable to genetic manipulation. Alternatively, we demonstrated that expression of HadA confers to a non-invasive Escherichia coli strain the ability to adhere to human cells and to extracellular matrix proteins and to induce in vitro bacterial aggregation and microcolony formation. Intriguingly, HadA is predicted to lack the typical N-terminal head domain of Oca proteins generally associated with cellular receptor binding. We propose here a structural model of the HadA coiled-coil stalk and show that the N-terminal region is still responsible of the binding activity and a KGD motif plays a role. Interestingly, HadA promotes bacterial entry into mammalian cells. Our results show a cytoskeleton re-arrangement and an involvement of clathrin in the HadA-mediated internalization. These data give new insights on the structure-function relationship of oligomeric coiled-coil adhesins and suggest a potential role of this protein in the pathogenesis of BPF.

Pneumococcal pili have been shown to influence pneumococcal colonization, disease development, and the inflammatory response in mice. The role of the pilus-associated RrgA adhesin in pneumococcal interactions with murine and human macrophages was investigated. Expression of pili with RrgA enhanced the uptake of pneumococci by murine and human macrophages that was abolished by antibodies to complement receptor 3 (CR3) and not seen in CR3-deficient macrophages. Recombinant RrgA, but not pilus subunit RrgC, promoted CR3-mediated phagocytosis of coated beads by murine and human macrophages. Flow cytometry showed that purified CR3 binds pneumococcal cells expressing RrgA, and purified RrgA was shown to interact with CR3 and its I domain. In vivo, RrgA facilitated spread of pneumococci from the upper airways and peritoneal cavity to the bloodstream. Earlier onset of septicemia and more rapidly progressing disease was observed in wild-type mice compared to CR3-deficient mice challenged intranasally or intraperitoneally with pneumococci. Motility assays and time-lapse video microscopy showed that pneumococcal stimulation of macrophage motility required RrgA and CR3. These findings, together with the observed RrgA-dependent increase of intracellular survivors up to 10 h following macrophage infection, suggest that RrgA-CR3-mediated phagocytosis promotes systemic pneumococcal spread from local sites.

Staphylococcus aureus is the major cause of human septic arthritis and osteomyelitis, which deserve special attention due to their rapid evolution and resistance to treatment. The progression of the disease depends on both bacterial presence in situ and uncontrolled disruptive immune response, which is responsible for chronic disease. Articular and bone infections are often the result of blood bacteremia, with the knees and hips being the most frequently infected joints showing the worst clinical outcome. We report the development of a hematogenous model of septic arthritis in murine knees, which progresses from an acute to a chronic phase, similarly to what occurs in humans. Characterization of the local and systemic inflammatory and immune responses following bacterial infection brought to light specific signatures of disease. Immunization of mice with the vaccine formulation we have recently described (4C-Staph), induced a strong antibody response and specific CD4+ effector memory T cells, and resulted in reduced bacterial load in the knee joints, a milder general inflammatory state and protection against bacterial-mediated cellular toxicity. Possible correlates of protection are finally proposed, which might contribute to the development of an effective vaccine for human use.Staphylococcus aureus is a human pathogen responsible for a variety of diseases ranging from minor/mild skin infections to life threatening diseases 1 . It is a major cause of bacteremia, which frequently leads to severe complications like endocarditis, toxic shock syndrome, septic arthritis (SA) and osteomyelitis (OM) 2 . Among others, joint-related diseases deserve special attention because of their rapid evolution and serious clinical outcomes, such as intense pain and impairment due to bone erosion requiring urgent intervention [3][4][5] . Joint infections are frequently localized in the knees and hips, and monoarticular disease is more frequent and less severe than polyarticular infection 6,7 . The mortality rate associated with these infections is around 5-20% in the adult population 3 , but can reach 50% depending on delayed diagnosis, immunodeficiency, older age 3,4 and pre-existing underlying conditions, such as rheumatoid arthritis and diabetes 3,8,9 . Joint and bone disruption is caused by the activity of bacteria in the joints, as well as by uncontrolled activation of the host immune system sustaining a local destructive inflammatory state, which can eventually result in chronic disease [10][11][12][13] . OM is often not treatable with antibiotics, a problem that is presently more evident with the increasing emergence of antibiotic-resistant S. aureus strains [14][15][16][17][18][19] . On the other hand, early application of antibiotic treatment can be efficacious for SA, which however often requires surgical intervention 3,4,7,20 .Given these premises, the development of an efficacious vaccine able to prevent S. aureus-mediated SA and OM would be highly desirable. We have recently demonstrated that an adjuvanted protein comb...

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This chapter discusses the key role of pili expressed by gram-positive bacterial pathogens in biofilm formation and the influence of environmental factors on their expression. The gram-positive bacterial pathogens described herein include Streptococcus pyogenes, Streptococcus agalactiae, Streptococcus pneumoniae, Enterococcus faecalis, E. faecium, and Actinomyces spp.

PurposeThis study provides a systematic literature review and categorization of the costs reported in the literature for the introduction of new vaccines, focusing on sub-Saharan Africa within LMICs, where vaccines are highly needed, financial resources are scarce and data are lacking and scattered.Design/methodology/approachA systematic literature search of PubMed and Web of Science databases was conducted according to the PRISMA requirements. Searches also included the relevant grey literature. In total, 39 studies were selected and nine cost categories were investigated to build a comprehensive framework.FindingsThe paper considers nine cost categories that cover the whole life of the vaccine, from its initial study to its full implementation, including for each of them the relevant subcategories. The systematic review, besides providing specific quantitative data and allowing to assess their variability within each category, points out that delivery, program preparation, administration and procurement costs are the most frequently estimated categories, while the cost of the good sold, costs borne by households and costs associated to AEFI are usually overlooked. Data reported on R&D costs and investment in the production plant differ significantly among the selected contributions.Originality/valueThe literature contributions on cost estimation tend to focus on a precise vaccine, a specific geographic area, or to adopt a narrow approach that captures only a subset of the costs. This article presents a rich and inclusive set of the economic quantitative data on immunization costs in limited-resource countries.