PNAG-specific equine IgG1 mediates significantly greater opsonization and killing of Prescottella equi (formerly Rhodococcus equi) than does IgG4/7. Issue 9 (21st February 2019)

• Record Type: Journal Article
• Authors: Rocha, Joana N.; Dangott, Lawrence J.; Mwangi, Waithaka; Alaniz, Robert C.; Bordin, Angela I.; Cywes-Bentley, Colette; Lawhon, Sara D.; Pillai, Suresh D.; Bray, Jocelyne M.; Pier, Gerald B.; Cohen, Noah D.
• Is Part Of: Vaccine. Volume 37:Issue 9(2019)
• Page Start: 1142
• Page End: 1150
• Publication Date: 2019-02-21
• Subjects: Intracellular bacteria -- Rhodoccus equi -- IgG1 -- IgG4/7 -- Complement -- Opsonization -- Opsonophagocytic killing; PNAG β-1→6-linked poly-N-acetyl glucosamine -- CFU colony forming unit -- C1 complement component 1 -- OPK opsonophagocytic killing -- PMN polymorphonuclear cells -- HIP hyperimmune plasma -- DEAE diethylaminoethyl -- SDS-PAGE sodium dodecyl sulfate polyacrylamide gel electrophoresis -- OD optical density -- ELISA enzyme-linked immunosorbent assay; Vaccines -- Periodicals; 615.372
• DOI: 10.1016/j.vaccine.2019.01.028
• Languages: English
• ISSNs: 0264-410X

Abstract

Highlights: Poly- N -acetyl glucosamine (PNAG), protects foals against Prescottella equi (Rhodococcus equi ) pneumonia. Anti-PNAG IgG1 is functionally more important than IgG4/7 at mediating protection. Anti-PNAG IgG1 deposited significantly more C1 onto PNAG than anti-PNAG IgG4/7 . Anti-PNAG IgG1 mediated significantly greater opsonic killing than anti-PNAG IgG4/7 . Anti-PNAG IgG1 is a correlate of protection against Prescottella (Rhodococcus) equi in foals. Abstract: Prescottella equi (formerly Rhodococcus equi ) is a facultative intracellular bacterial pathogen that causes severe pneumonia in foals 1–6 months of age, whereas adult horses are highly resistant to infection. We have shown that vaccinating pregnant mares against the conserved surface polysaccharide capsule, β-1 → 6-linked poly- N -acetyl glucosamine (PNAG), elicits opsonic killing antibody that transfers via colostrum to foals and protects them against experimental infection with virulent. R. equi . We hypothesized that equine IgG1 might be more important than IgG4/7 for mediating protection against R. equi infection in foals. To test this hypothesis, we compared complement component 1 (C1) deposition and polymorphonuclear cell-mediated opsonophagocytic killing (OPK) mediated by IgG1 or IgG4/7 enriched from either PNAG hyperimmune plasma (HIP) or standard plasma. Subclasses IgG1 and IgG4/7 from PNAG HIP and standard plasma were precipitated onto a diethylaminoethyl ion exchange column, then further enriched using a protein G Sepharose column. We determined C1 deposition by enzyme-linked immunosorbent assay (ELISA) and estimated OPK by quantitative microbiologic culture. Anti-PNAG IgG1 deposited significantly (P < 0.05) more C1 onto PNAG than did IgG4/7 from PNAG HIP or subclasses IgG1 and IgG4/7 from standard plasma. In addition, IgG1 from PNAG HIP mediated significantly (P < 0.05) greater OPK than IgG4/7 from PNAG HIP or IgG1 and IgG4/7 from standard plasma. Our findings indicate that anti-PNAG IgG1 is a correlate of protection against R. equi in foals, which has important implications for understanding the immunopathogenesis of R. equi pneumonia, and as a tool for assessing vaccine efficacy and effectiveness when challenge is not feasible.