Bordetella pertussis (Bp) is the etiologic agent of pertussis (whooping cough), a highly communicable infection. Although pertussis is vaccine preventable, in recent years there has been increased incidence, despite high vaccine coverage. Possible reasons for the rise in cases include the following: Bp strain adaptation, waning vaccine immunity, increased surveillance, and improved clinical diagnostics. A pertussis outbreak impacted California (USA) in 2010; children and preadolescents were the most affected but the burden of disease fell mainly on infants. To identify protein biomarkers associated with this pertussis outbreak, we report a whole cellular protein characterization of six Bp isolates plus the pertussis acellular vaccine strain Bp Tohama I (T), utilizing gel-free proteomics-based mass spectrometry (MS). MS/MS tryptic peptide detection and protein database searching combined with western blot analysis revealed three Bp isolates in this study had markedly reduced detection of pertactin (Prn), a subunit of pertussis acellular vaccines. Additionally, antibody affinity capture technologies were implemented using anti-Bp T rabbit polyclonal antisera and whole cellular proteins to identify putative immunogens. Proteome profiling could shed light on pathogenesis and potentially lay the foundation for reduced infection transmission strategies and improved clinical diagnostics.

Mass spectrometry (MS) coupled with 1-D and 2-D electrophoresis can be utilized to detect and identify immunogenic proteins, but these methods are laborious and time-consuming. We describe an alternative, simple, rapid gel-free strategy to identify multiple immunogenic proteins from Bordetella pertussis (Bp). It couples immunoprecipitation to nano liquid chromatography- tandem mass spectrometry (IP-nLC-MS/MS) and is significantly both time- and labor-saving. We developed a gel-free magnetic bead-based immunoprecipitation (IP) method using different NP-40/PBS concentrations in which solubilized proteins of Bp Tohama I membrane fractions were precipitated with polyclonal rabbit anti-Bp whole cell immune sera. Immune complexes were analyzed by MS and Scaffold analysis (>95% protein identification probability). Total immunoproteins identified were 50, 63 and 49 for 0.90%, 0.45% and 0.22% NP-40/PBS buffer concentrations respectively. Known Bp proteins identified included pertactin, serotype 2 fimbrial subunit and filamentous hemagglutinin. As proof of concept that this gel-free protein immunoprecipitation method enabled the capture of multiple immunogenic proteins, IP samples were also analyzed by SDS-PAGE and immunoblotting. Bypassing gels and subjecting immunoprecipitated proteins directly to MS is a simple and rapid antigen identification method with relatively high throughput. IP-nLC-MS/MS provides a novel alternative approach for current methods used for the identification of immunogenic proteins.

Many studies suggest that with aging, immune capabilities gradually diminish, leading to a decrease in antibody production, cytokines, and various effector cells (1-4). In this study, we examined the effects of an immune-enhancing peptide on aged mice. P4, a 28-amino-acid cationic peptide derived from pneumococcal surface adhesin A (PsaA), is a eukaryotic cellular activator (10). Previously, we demonstrated that the cellular activation properties of P4 can be utilized to rescue severely ill young mice from fatal pneumococcal infection in the presence of pathogen-specific antibodies and active complement (8, 12). While P4 therapy was used to rescue young Swiss Webster mice (6 to 10 weeks old), we questioned its effectiveness in aged mice (11 and 15 months old). | Intranasal inoculation of mice with Streptococcus pneumoniae WU2 (serotype 3) and P4 therapy were done using protocols previously described, with minor modifications (12). Eleven-month-old BALB/c (n = 20) and 15-month-old Swiss Webster mice (n = 20) were infected intranasally with S. pneumoniae WU2 (∼2.1 × 107 cells/mouse). Mice were monitored and visually scored twice daily for moribund characteristics as previously described (12). At 48 h postchallenge, 80% (16/20) were moribund. Moribund mice were divided into a control (n = 8) and a treatment group (n = 8). Two doses of P4 therapy with pathogen-specific antibody (intravenous immunoglobulin [IVIG]; Gamunex, Telecris, NC) and P4 were administered intravenously (postinfection) in the treatment group. Treated and untreated animals were monitored for 166 h, and the data computed for significant differences among various groups using a t test for paired samples for the means (MS Excel 2007).

Bordetella pertussis (Bp) is the causative agent of pertussis, a vaccine preventable disease occurring primarily in children. In recent years, there has been increased reporting of pertussis. Current pertussis vaccines are acellular and consist of Bp proteins including the major virulence factor pertussis toxin (Ptx), a 5-subunit exotoxin. Variation in Ptx subunit amino acid (AA) sequence could possibly affect the immune response. A blind comparative mass spectrometric (MS) analysis of commercially available Ptx as well as the chemically modified toxoid (Ptxd) from licensed vaccines was performed to assess peptide sequence and AA coverage variability as well as relative amounts of Ptx subunits. Qualitatively, there are similarities among the various sources based on AA percent coverages and MS/MS fragmentation profiles. Additionally, based on a label-free mass spectrometry-based quantification method there is differential relative abundance of the subunits among the sources.

A murine colonization model was used to determine the effect of co-administering 7-valent polysaccharide-protein conjugate vaccine and pneumococcal surface adhesin A. Mice were challenged intranasally with either PCV7 serotypes, 4 or 14, or a non-PCV7 serotype, 19A. Post-challenge samples were evaluated for IgG antibody levels, opsonophagocytic activity, and nasopharyngeal colonization. No interference was observed between immune responses from the concomitant and individual immunizations. Concomitant immunizations reduced carriage for tested serotypes; largest reduction was observed for 19A. From these mouse studies, co-administering pneumococcal antigens appear to expand coverage and reduce colonization against a non-PCV7 serotype without inhibiting immunogenicity to other serotypes.