Naturally occurring IgG antibody levels to the Staphylococcus aureus protein IsdB in humans

• Published in: Human vaccines & immunotherapeutics Vol. 9; no. 9; pp. 1857 - 1864
• Main Authors: Zorman, Julie K, Esser, Mark, Raedler, Michael, Kreiswirth, Barry N, Ala'aldeen, Dlawer AA, Kartsonis, Nicholas, Smugar, Steven S, Anderson, Annaliesa S, McNeely, Tessie, Arduino, Jean Marie
• Format: Journal Article
• Language: English
• Published: United States Taylor & Francis 01.09.2013; Landes Bioscience
• Subjects: Adult; Aged; Aged, 80 and over; Antibodies, Bacterial - blood; antibody levels; Cation Transport Proteins - immunology; Female; healthy subjects; Healthy Volunteers; hospitalized patients; Humans; Immunoglobulin G - blood; Inpatients; IsdB; Male; Middle Aged; Research Paper; S. aureus infection; Staphylococcal Infections - immunology; Young Adult; antibody levels; hospitalized patients; IsdB; S. aureusinfection; healthy subjects
• ISSN: 2164-5515; 2164-554X; 2164-554X
• DOI: 10.4161/hv.25253

Staphylococcus aureus is a well-recognized, clinically important cause of nosocomial infections, and as such, a vaccine to prevent S. aureus infections would be an important achievement. A Phase IIB/III study of V710, a vaccine containing iron-regulated surface determinant B (IsdB), demonstrated significant sero-conversion rates in cardiovascular surgery patients following a single pre-surgery immunization. However, the vaccine was not efficacious in preventing bacteremia or deep sternal wound infection post-surgery, thus raising the possibility that IsdB might not be available for immune recognition during infection. The purpose of the work described herein was to evaluate and quantify the naturally occurring anti-IsdB levels at baseline and over time during infection, to understand whether IsdB is expressed during a S. aureus infection in hospitalized non-vaccinated patients. We evaluated baseline and follow-up titers in 3 populations: (1) healthy subjects, (2) hospitalized patients with non-S. aureus infections, and (3) hospitalized patients with S. aureus infections. Baseline anti-IsdB levels generally overlapped between the 3 groups, but were highly variable within each group. In healthy subjects, baseline and follow-up levels were highly correlated (Spearman's rho = 0.93), and the geometric mean fold-rise (GMFR) in anti-IsdB levels between study entry and last value was 0.9-fold (95% confidence interval (CI): 0.8 to 1.0 ; p = 0.09), showing no trend over time. The convalescent GMFR in anti-IsdB levels from baseline was 1.7-fold (95% CI: 1.3 to 2.2, p = 0.0008) during S. aureus infection, significantly different from the 1.0-fold GMFR (95% CI: 0.9-1.2, p = 0.60) in non-S. aureus infection, p = 0.005. Additionally, S. aureus isolates (51) obtained from the hospitalized patient group expressed the IsdB protein in vitro. Collectively, these data suggest that IsdB expression levels rise substantially following infection with S. aureus, but not with other pathogens, and IsdB is likely well-conserved across S. aureus strains.