The Harry M. Zweig Memorial Fund for Equine Research


T-Cell Mediated Immunity and Vaccine Development in Horses

Dr. Douglas F. Antczak

AntczakDr. Douglas F. Antczak

The long-term goal of this research is to facilitate development of more effective vaccines against intracellular pathogens of the horse, such as equine herpesvirus type 1 (EHV-1), equine influenza (EIV), and Rhodococcus equi (R. equi).  Vaccines for these microorganisms are not yet available or only partially effective.  T-lymphocyte (T-cell) immunity is critical for protection against intracellular pathogens; however, details of the antigens recognized by T-cells and assays for measuring specific T-cell responses are not available for the horse.  The T-cell receptor recognizes pathogen-derived peptides held in the binding groove of Major Histocompatibility Complex (MHC) molecules on the surface of infected cells.  Our objective is to identify the immunogenic peptides bound by the most common equine MHC class I molecules.  This information would advance the long-term goal of development of new diagnostic tools and improved vaccines.  Hypothesis: We propose that it is possible to identify immunogenic peptides recognized by equine T-cells through experiments that use genomic information from both host and pathogen.

 

Specific Aims:

1) To identify the most important MHC class I molecule that presents immunogenic peptide after EHV-1 infection in a common and well-studied horse MHC type;

2) To determine the amino acid sequence of the EHV-1 peptide bound by that MHC class I molecule;

3) To use the identified EHV-1 peptide sequence to predict peptides from other horse pathogens that bind to this MHC class I molecule.  

For Aim 1 we have engineered mouse cell lines expressing individual horse MHC class I genes that would be transduced with EHV-1 genes and used as target cells in cytotoxic T-cell assays.  In Aim 2 we would use two strategies to determine the precise amino acid sequence of the most immunogenic EHV-1 peptide.  This sequence would be modified by site-directed amino acid exchanges to identify the so-called ‘anchor residues’ of the peptide.  In Aim 3 we would use the anchor residues of the peptide in bioinformatic approaches to scan for potential antigenic peptides from EIV and R. equi.  Depending upon progress, this experimental template would be applied to MHC class I molecules of other horse MHC types.  Expected outcome: the information we expect to obtain will enable the development of sensitive diagnostic probes (e.g. MHC tetramers) that can measure pathogen-specific cytotoxic T-cell responses.  Ultimately, highly immunogenic pathogen-derived peptides could be incorporated into a new class of synthetic vaccines for EHV-1 or other pathogens tailored for the MHC types of specific breeds, such as the Thoroughbred or Standardbred.  This would be the first instance of a vaccine designed on the basis of genomic information from horse and pathogen.  Our research team is uniquely positioned to undertake this study, and Cornell also has the resource of Thoroughbred horses bred for MHC homozygosity that are required for this work.