2015 ACVIM Forum Research Abstract Program

Stepwise decreases in IgG values <800 mg/dL were proportionally associated with non-survival. Hospitalized foals with any degree of FTPI were 3.5-10 times more likely to die. There were no statistical differences in non-survival if foals had IgG concentrations between 801-1200 mg/dL compared to those with >1200 mg/dL. Foals with hyperproteinemia also had higher mortality rates. We recommend immediate assessment of IgG concentrations in hospitalized foals and those with FTPI should receive prompt immunotherapy. The purpose of this pilot study was to compare both systemic and local immune responses following intranasal or oral vaccination for Streptococcus equi var equi. Eight healthy horses with Streptococcus equi M protein titers <1:1600 were vaccinated with a live-attenuated vaccine intranasally per label instructions or transmucosally (orally) in a two-vaccine series. Both serum and nasal secretions were collected for baseline and 2-and 4-week post booster vaccinations for detection of IgG and IgA. Antibody assessment was performed using a commercially available ELISA for M protein titers and using a novel microbead assay analyzed by the Luminex TM Magpix instrument which utilizes flow cytometric principles. Horses vaccinated by the intranasal route demonstrated a substantial increase in both serum IgG and serum IgA M protein antibody levels post vaccination (P = 0.0006 and P = 0.007, respectively). Horses that were vaccinated by the oral route also demonstrated an increase in the serum IgG M protein antibody levels post vaccination (P = 0.0150), though the increase was of approximately one third the magnitude of that observed in intranasal vaccinates. Orallyvaccinated horses did not show any evidence of response in serum IgA post vaccination (P = 0.15). Because of the small scale of the study, study design limitations, and the unknown protective level of IgG against S. equi, the findings of this study should be interpreted carefully. Results from this study indicate that horses that received the live-attenuated Pinnacle Ã’ Streptococcus equi var equi vaccine either through intranasal or oral routes showed an increase in serum IgG M protein titer, though the magnitude of the response differed between administration routes. Major histocompatibility complex (MHC) I and II expression is not detected in normal muscle and appears to be a prerequisite for the autoimmune cytotoxicity that occurs in muscle from humans and dogs with immune-mediated myositis (IMM). The purpose of this study was to characterize lymphocyte subtypes in muscle biopsies of suspected IMM horses and determine if MHC I and II expression occurs in myocytes.