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.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.