Oral Presentation International Veterinary Immunology Symposium 2016

Host immunity against equine herpesvirus type 1 (EHV-1) in a model of immunologically naive horses. (#68)

Bettina Wagner 1
  1. Cornell University College of Veterinary Medicine, Ithaca, NEW YORK, United States

Immune responses in animals are influenced by their heterogenicity and previous exposure to environmental antigens and pathogens. In horses, the accumulated immunological experience of the mare is transferred to the neonatal foal with the colostrum at birth. Maternal antibodies are believed to inhibit specific immune responses of the neonate for several weeks after birth. Indeed, adaptive immune responses of young foals develop slowly. When vaccinated with conventional vaccines, neonatal and young foals are typically not or only weakly responding. This can make it challenging to protect young foals against pathogens that are transmitted early in life. Nevertheless, several innate immune mechanisms and individual antibody isotype responses of neonatal and young foals are similar or even increased when compared to adults. We have developed a model of horses that are immunologically naïve to several pathogens including equine herpesvirus type 1 (EHV-1) to explore a novel vaccination strategy for neonatal foals. The neonatal vaccine was targeting an innate immune mechanism of neonatal foals to increase interleukin 4 (IL-4) production with the goal to enhance EHV-1-specific B-cell differentiation and antibody development. The neonatal EHV-1 vaccine was given immediately after birth. At weanling age, foals were experimentally infected with EHV-1. Vaccinated foals showed reduced fever compared to the non-vaccinated controls foals. Neonatal vaccination also resulted in faster and significantly increased intranasal and systemic antibody production. Antibody responses were dominated by IgG1, IgG4, and IgG7 isotypes. Peripheral blood mononuclear cells (PBMC) from vaccinated foals also showed IFN-gamma dominated responses after re-stimulation with EHV-1, while PBMC from non-vaccinated foals expressed IL-4 and IL-10 dominated responses. In summary, neonatal vaccination targeting innate immunity to induce B-cell development against EHV-1 increases immune awareness and antibody responses and reduces clinical signs after EHV-1 infection.

This work was supported by the Zweig Memorial Fund for Equine Research and USDA/NIFA.