With the recent increase in outbreaks of neurological form of equine herpesvirus-1 reported at several racing tracks, private boarding facilities and veterinary hospitals throughout North America, our laboratory has been committed to the timely and emerging needs of the equine industry. We have investigated several aspects of the pathophysiology, epidemiology and diagnosis of this disease. Using state-of-the-art technology, we have characterized the cytokine profile in brain tissue samples from affected animals and determined that equine herpesvirus-1 positive neural tissues expressed mainly pro-inflammatory cytokines. The investigation of the epidemiology of this disorder was performed at different venues, including breeding farms, race tracks and veterinary hospitals. The information gained from these studies has allowed us to determine risk factors of transmission and to scientifically establish sound biosecurity guidelines. Further, equine herpesvirus-1 has been at the center of several controversial decisions mainly due to the lack of diagnostic tools. Our laboratory has not only investigated novel and more reliable ways to determine with accuracy the stage of the disease but has also worked at better defining the state of the virus. We have instituted novel guidelines for reporting quantitative molecular results, which have made tremendous improvements in the interpretation of PCR results, enabling veterinarians to determine the infectious nature of index cases, disease stage or response to antiviral therapy. The novelty of our approach lies in reporting results quantitatively, in determining the replicative potential of the virus and in targeting multiple genes in order to determine the virulence of the viral strain involved with an outbreak. Reporting reliable and useful molecular diagnostic results has become crucial since practicing veterinarians and regulatory officials who submit samples and receive positive PCR test results are typically unaware of the complexities involved in test interpretation and could decide to quarantine equine facilities or cancel competitions based on misinterpreted test results.
We are currently investigating the risk factors associated with recrudescence of latent infection, characterizing the viral stage, state and strain of equine herpesvirus-1 in the trigeminal ganglion of horses undergoing routine necropsy, and determining the efficiency of equine herpesvirus-1 transmission between horses undergoing corticosteroid-induced reactivation of latent infection and naïve horses. Further, in collaboration with Merck Animal Health, we have established a national surveillance program for respiratory pathogens, which will allow us to gather valuable epidemiological information during outbreaks.
Review articles (PDFs)
PUSTERLA, N., W.D. WILSON, J.E. MADIGAN and G.L. FERRARO (2009). Equine herpesvirus-1 myeloencephalopathy. A review of recent developments. Vet. J. 180, 279-289.
LUNN, D.P., N. DAVIS-POYNTER, M.J. FLAMINIO, D.W. HOROHOV, K. OSTERRIEDER, N. PUSTERLA and H.G. TOWNSEND (2009). Equine herpesvirus-1 consensus statement. J. Vet. Intern. Med. 23, 450-461.