Improved vaccine strategies for management of equine herpesviruses

Improved vaccine strategies for management of equine herpesviruses Publication No. 02/111 Project No. UMA 15A The views expressed and the conclusions reached in this publication are those of the author and not necessarily those of persons consulted. RIRDC shall not be responsible in any way whatsoever to any person who relies in whole or in part on the contents of this report. In submitting this report, the researcher has agreed to RIRDC publishing this material in its edited form. iii Foreword As outlined in the background to the Equine Research and Development Program of RIRDC, the horse industry is one of Australia's biggest industries and is worth more than $15 billion a year. There are more than 1.2 million horses used for racing, equestrian sports, and recreation and there is a large breeding industry, with Australia producing the second highest number of thoroughbred foals in the world, after the United States. Minimization of infectious diseases is important for effective management throughout the industry. Among infectious agents recognized as posing a serious and ongoing threat are the equine herpesviruses (EHV), in particular EHV-1 which can cause abortion in pregnant mares and neurological disease. These outcomes can be financially disastrous for breeders, while respiratory illness caused by both EHV-1 and the related EHV-4 can adversely affect racing performance. Therefore, consistent with the first RIRDC Five-Year Plan, the objectives of the project were to improve reproductive efficiency and respiratory health in horse populations through reduction of incidence of herpesvirus abortion and respiratory infection. Prior to 1997 in Australia, we were in the unusual position of being able to investigate the epidemiology of EHV-1 and EHV-4 in unvaccinated horse populations. Building on this background, the project aimed a) to obtain updated information on the prevalence of EHV-1 in a population of horses that had been routinely vaccinated with an imported vaccine introduced in 1997 b) to investigate the use of the vaccine in the field and c) to make a preliminary assessment of the potential of new types of vaccines for EHV 1 and EHV-4 based on recombinant DNA methodology. The report details the results of large scale serological surveys of the prevalence of antibody to EHV-1 and compares this 2000 data with that of 1995, obtained prior to vaccination. Secondly by using similar serological analysis and sampling mares and foals intensively over time, the percentage of mares and foals that respond to vaccination …