Immune modulation of IgE and T regulatory cells in horses vaccinated with viral vaccines. (VET1P.1117)

Abstract

Abstract West Nile virus (WNV) a neurotropic flavivirus is the leading cause of mosquito-borne encephalitis in the United States. While there is no current WNV vaccine for humans there are several vaccines for horses. These vaccines are designed to protect against this deadly virus; however, many are causing type-1 hypersensitivity IgE-mediated allergic responses that include local and severe systemic anaphylaxis. Many viral vaccines share contaminating non-target proteins that can act as antigen to elicit IgE. We compared IgE levels to those of T regulatory cell populations’ pre and post vaccination, which showed a significant inverse correlation. We hypothesize the addition of CpG oligonucleotides administered with vaccines will modulate the immune system, driving it towards protective immunity, through up-regulation of T helper 1 cells. Thirty horses were evaluated pre and 7 days post vaccination for T regulatory cell production and specific IgE. Peripheral blood mononuclear cells isolated pre and post vaccination were analyzed for expression of CD4, CD25 and intracellular Foxp3 with multicolor flow cytometry. Antigen specific IgE and cytokine supernatants were evaluated by ELISA. The addition of the CpG oligonucleotide significantly increased the production of T regulatory cells in response to antigen in-vitro and in-vivo; with this we can hope to provide a safer alternate vaccination strategy, particularly for horses that have demonstrated a pro-allergic phenotype.