The immune response of pigs to aerosolized pseudorabies virus
Abstract
Respiratory diseases are extremely costly to the swine industry worldwide and ongoing research is essential for gaining a better understanding of the pathogenesis, diagnosis, and prevention of respiratory disease. Because of the plethora of confounding factors on the farm, more efficient research can be carried out under laboratory conditions and virus-induced pneumonia in young pigs is a suitable model for examining the response of the immune system to a respiratory pathogen. In this thesis two modes of Pseudorabies virus-induced pneumonia in young pigs were examined. The first mode instilled a viral suspension into the nares of conventionally derived young pigs (model 1). For the second mode, conventionally derived pigs (model 2) or very high health status pigs (model 3) were exposed to virus-ladened aerosols. Scoring systems for evaluating clinical responses to the infection were developed for comparisons among the three models. For the examination of the immune response to experimental aerosols, methods for repeatedly collecting free alveolar cells by lavage of the lung and collecting peripheral blood lymphocytes were also developed. The changes in viability and numbers of alveolar macrophages from infected pigs were assessed. The temporal development of serum neutralizing antibodies against Pseudorabies virus and a virus-specific lymphoproliferative response of peripheral lymphocytes of experimental aerosol exposed pigs was described. The evolution and decline of CD4/CD8 phenotypic subsets among white blood cells and isolated peripheral mononuclear cells were plotted over time. The very high health status pig demonstrated a consistent grow curve. In spite of the one week “setback” in growth from Pseudorabies, the infected pigs demonstrated “compensatory gain” such that within two weeks after recovery from clinical signs of disease they had attained live weights, which were similar to the uninfected pigs. Evaluation techniques developed in a very high health status young pig seem to offer promise for understanding how to optimize the respiratory immune response and reduce the cost of respiratory diseases to the pig industry.
Degree
Ph.D.
Advisors
Kanitz, Purdue University.
Subject Area
Veterinary services|Immunology|Animal diseases|Microbiology
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