Next generation pneumococcal vaccines Moffitt, Kristin L; Malley, Richard
Current opinion in immunology,
06/2011, Letnik:
23, Številka:
3
Journal Article
Recenzirano
Odprti dostop
Highlights ► Currently licensed pneumococcal vaccines are effective but also have limitations for worldwide use. ► There is much interest in the development of novel, broad pneumococcal vaccines. ► ...Antibodies or effector T cells directed against conserved pneumococcal proteins are protective. ► Three novel vaccine approaches: modified conjugates, protein-based, or an inactivated whole cell vaccine.
Streptococcus pneumoniae remains one of the most frequent bacterial causes of morbidity and mortality worldwide. National immunization programs implementing pneumococcal polysaccharide conjugate ...vaccines (PCVs) have successfully reduced rates of vaccine-type invasive disease and colonization both via direct effects in immunized children and, in some settings, indirect effects in unimmunized individuals. Limitations of the current PCV approach include the emergence of non-vaccine serotypes contributing to carriage and invasive disease in high-PCV coverage settings and the high cost of goods of PCVs which limits their accessibility in developing countries where the burden of disease remains highest. Furthermore, the distribution of serotypes causing disease varies geographically and includes more serotypes than are currently covered in a single PCV formulation. Researchers have long been exploring the potential of genetically conserved non-capsular pneumococcal antigens as vaccine candidates that might overcome such limitations. To better evaluate the rationale of such approaches, an understanding of the mechanisms of immunity to the various phases of pneumococcal infection is of paramount importance. Herein we will review the evolving understanding of both vaccine-induced and naturally acquired immunity to pneumococcal colonization and infection and discuss how this informs current approaches using serotype-independent pneumococcal vaccine candidates. We will then review the alternative vaccine candidates that have been or are currently under evaluation in clinical trials.
Mucosal or parenteral immunization with a killed unencapsulated pneumococcal whole cell antigen (WCA) with an adjuvant protects mice from colonization by a TH17 CD4+ cell-mediated mechanism. Using ...preparative SDS gels, we separated the soluble proteins that compose the WCA in order to identify fractions that were immunogenic and protective. We screened these fractions for their ability to stimulate IL-17A secretion from splenocytes obtained from mice immunized with WCA and adjuvant. We identified 12 proteins within the stimulatory fractions by mass spectrometry; these proteins were then cloned, recombinantly expressed and purified using an Escherichia coli expression system. The ability of these proteins to induce IL-17A secretion was then evaluated by stimulation of mouse splenocytes. Of the four most stimulatory proteins, three were protective in a mouse pneumococcal serotype 6B colonization model. This work thus describes a method for identifying immunogenic proteins from the soluble fraction of pneumococcus and shows that several of the proteins identified protect mice from colonization when used as mucosal vaccines. We propose that, by providing protection against pneumococcal colonization, one or more of these proteins may serve as components of a multivalent pneumococcal vaccine.
Streptococcus pneumoniae is a leading cause of mortality in young children. While successful conjugate polysaccharide vaccines exist, a less expensive serotype-independent protein-based pneumococcal ...vaccine offers a major advancement for preventing life-threatening pneumococcal infections, particularly in developing nations. IL-17A-secreting CD4+ T cells (T(H)17) mediate resistance to mucosal colonization by multiple pathogens including S. pneumoniae. Screening an expression library containing >96% of predicted pneumococcal proteins, we identified antigens recognized by T(H)17 cells from mice immune to pneumococcal colonization. The identified antigens also elicited IL-17A secretion from colonized mouse splenocytes and human PBMCs suggesting that similar responses are primed during natural exposure. Immunization of two mouse strains with identified antigens provided protection from pneumococcal colonization that was significantly diminished in animals treated with blocking CD4 or IL-17A antibodies. This work demonstrates the potential of proteomic screening approaches to identify specific antigens for the design of subunit vaccines against mucosal pathogens via harnessing T(H)17-mediated immunity.
Mucosal or parenteral immunization with a killed unencapsulated pneumococcal whole cell antigen (WCA) with an adjuvant protects mice from colonization by a T(H)17 CD4+ cell-mediated mechanism. Using ...preparative SDS gels, we separated the soluble proteins that compose the WCA in order to identify fractions that were immunogenic and protective. We screened these fractions for their ability to stimulate IL-17A secretion from splenocytes obtained from mice immunized with WCA and adjuvant. We identified 12 proteins within the stimulatory fractions by mass spectrometry; these proteins were then cloned, recombinantly expressed and purified using an Escherichia coli expression system. The ability of these proteins to induce IL-17A secretion was then evaluated by stimulation of mouse splenocytes. Of the four most stimulatory proteins, three were protective in a mouse pneumococcal serotype 6B colonization model. This work thus describes a method for identifying immunogenic proteins from the soluble fraction of pneumococcus and shows that several of the proteins identified protect mice from colonization when used as mucosal vaccines. We propose that, by providing protection against pneumococcal colonization, one or more of these proteins may serve as components of a multivalent pneumococcal vaccine.
Respiratory coinfection of influenza with Staphylococcus aureus often causes severe disease; methicillin-resistant S. aureus (MRSA) coinfection is frequently fatal. Understanding disease pathogenesis ...may inform therapies. We aimed to identify host and pathogen transcriptomic (messenger RNA) signatures from the respiratory compartment of pediatric patients critically ill with influenza-S. aureus coinfection (ISAC), signatures that predict worse outcomes. Messenger RNA extracted from endotracheal aspirate samples was evaluated for S. aureus and host transcriptomic biosignatures. Influenza-MRSA outcomes were worse, but of 190 S. aureus virulence-associated genes, 6 were differentially expressed between MRSA-coinfected versus methicillin-susceptible S. aureus-coinfected patients, and none discriminated outcome. Host gene expression in patients with ISAC was compared with that in patients with influenza infection alone. Patients with poor clinical outcomes (death or prolonged multiorgan dysfunction) had relatively reduced expression of interferons and down-regulation of interferon γ-induced immune cell chemoattractants CXCL10 and CXCL11. In ISAC, airway host but not pathogen gene expression profiles predicted worse clinical outcomes.
Abstract
Background
Coinfection with influenza virus and methicillin-resistant Staphylococcus aureus (MRSA) causes life-threatening necrotizing pneumonia in children. Sporadic incidence precludes ...evaluation of antimicrobial efficacy. We assessed the clinical characteristics and outcomes of critically ill children with influenza-MRSA pneumonia and evaluated antibiotic use.
Methods
We enrolled children (<18 years) with influenza infection and respiratory failure across 34 pediatric intensive care units 11/2008-5/2016. We compared baseline characteristics, clinical courses, and therapies in children with MRSA coinfection, non-MRSA bacterial coinfection, and no bacterial coinfection.
Results
We enrolled 170 children (127 influenza A, 43 influenza B). Children with influenza-MRSA pneumonia (N = 30, 87% previously healthy) were older than those with non-MRSA (N = 61) or no (N = 79) bacterial coinfections. Influenza-MRSA was associated with increased leukopenia, acute lung injury, vasopressor use, extracorporeal life support, and mortality than either group (P ≤ .0001). Influenza-related mortality was 40% with MRSA compared to 4.3% without (relative risk RR, 9.3; 95% confidence interval CI, 3.8-22.9). Of 29/30 children with MRSA who received vancomycin within the first 24 hours of hospitalization, mortality was 12.5% (N = 2/16) if treatment also included a second anti-MRSA antibiotic compared to 69.2% (N = 9/13) with vancomycin monotherapy (RR, 5.5; 95% CI, 1.4, 21.3; P = .003). Vancomycin dosing did not influence initial trough levels; 78% were <10 µg/mL.
Conclusions
Influenza-MRSA coinfection is associated with high fatality in critically ill children. These data support early addition of a second anti-MRSA antibiotic to vancomycin in suspected severe cases.
Influenza-methicillin-resistant Staphylococcus aureus (MRSA) coinfection is associated with high fatality in children. In this multicenter study, mortality was lower in critically ill children treated early with a second anti-MRSA antibiotic in addition to vancomycin compared to those who received vancomycin monotherapy.
Highlights ► We show the immunologic responses to a species-specific pneumococcal whole cell vaccine administered with aluminum hydroxide. ► Antibody elicited by the vaccine cross-reacts to a panel ...of clinical pneumococcal isolates of diverse MLST and serotypes. ► Immunization with this vaccine primes T cells to produce robust IL-17A responses to pneumococci regardless of serotype. ► This data suggest broad responses and provide further support for the clinical development of this vaccine.
Highlights • Pneumococcal whole cell vaccine (PWCV) antibodies bind to encapsulated pneumococcal strains. • C3 deposition analyzed by flow cytometry detected subtle differences in PWCV quality. • ...Anti-PWCV induces opsonophagocytosis killing (OPK) of different pneumococcal strains. • IL-17A activates killing of opsonized strains, in the absence of complement. • C3 deposition and OPK assays could be further explored for quality control of PWCV.
The available pneumococcal conjugate vaccines provide protection against only those serotypes that are included in the vaccine, which leads to a selective pressure and serotype replacement in the ...population. An alternative low‐cost, safe and serotype‐independent vaccine was developed based on a nonencapsulated pneumococcus strain. This study evaluates process intensification to improve biomass production and shows for the first time the use of perfusion‐batch with cell recycling for bacterial vaccine production. Batch, fed‐batch, and perfusion‐batch were performed at 10 L scale using a complex animal component‐free culture medium. Cells were harvested at the highest optical density, concentrated and washed using microfiltration or centrifugation to compare cell separation methods. Higher biomass was achieved using perfusion‐batch, which removes lactate while retaining cells. The biomass produced in perfusion‐batch would represent at least a fourfold greater number of doses per cultivation than in the previously described batch process. Each strategy yielded similar vaccines in terms of quality as evaluated by western blot and animal immunization assays, indicating that so far, perfusion‐batch is the best strategy for the intensification of pneumococcal whole‐cell vaccine production, as it can be integrated to the cell separation process keeping the same vaccine quality.
Process intensification to improve biomass was evaluated for production of pneumococcal whole‐cell vaccine. The process intensification was achieved by the integration of the perfusion with the cell separation system, which uses the same space and equipment as batch or fed‐batch, also diminishing the auxiliary time. The perfusion‐batch allowed producing 3‐fold higher biomass than batch and fed‐batch processes. The potential impact of intensification on the quality of the final product was evaluated and no quality differences among the vaccines were observed.
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