KSEF R&D Excellence Proposal: Development of Gene Delivery Approaches to Treat Equine Respiratory Diseases

Development of gene delivery approaches to treat equine respiratory diseases David W. Horohov, Ph.D. William Robert Mills Chair in Equine Immunology R. Prank Cook, Ph.D. Research Assistant Professor MaxweII H. Gluck Equine Research Center Department of Veterinary Science University of Kentucky Lexington, KY 40546-0099 Inflammatory airway disease remains a significant economic burden to the equine industry. While the eliciting agent can be either infectious or non-infectious, immunological responses playa central role in the pathology. Young horses are highly susceptible to bacterial and viral infections of the airway and decreased expression of interferon-gamma is associated with this increased susceptibility to infection. Older horses, by contrast, suffer from a chronic airway inflammatory condition known as "heaves." In the older horse this condition is aIIergic in nature and immunologicaIIy resembles certain forms of asthma. In particular, heaves is associated with elevated levels of the cytokine (interleukin-4) that regulates IgE production. As the underlying immunological bases for these diseases are becoming better understood, the possibility exists for novel therapeutic approaches. Therapies to date have been directed towards symptomatic relief in the affected horse. Here we propose to address the underlying immunological dysfunction. Our approach will be to develop gene delivery methods that will allow for the transient expression of specific genes within the equine lung. This approach may be used to either enhance or suppress cytokine expression and thus alter the immune response in the lung. Enhancement may be accomplished by expressing the gene of interest under a strong promoter. Suppression of gene expression may be accomplished using short interfering RNAs (siRNA) to silence gene expression. We wiII try both viral and non-viral delivery methods. Both approaches have shown promise in other model systems and each offers different capabilities in terms of ceII targeting. Initially we will utilize florescent marker genes that will aIIow us to determine optimal gene delivery and expression efficiencies in the equine lung. Based on this information, we wiII then develop suitable vectors for the expression of equine interferon-gamma and siRNA for interleukin-4 for later use in the equine lung.