"African swine fever virus (ASFV) causes a reportable and often fatal disease of domestic pigs and wild boars. The current absence of effective prophylaxis or countermeasures makes it a significant agricultural and economic hazard within affected and neighboring regions. Despite extensive ASF research, key elements of the virus-host interaction have yet to be fully explained. Contributing to this knowledge gap is the lack of congruence in infection models amongst investigators. An infection/challenge model that closely simulates natural infection while using precise, measurable inoculation methods, and providing reproducible and quantifiable results is imperative for successful ASFV research and countermeasure development. This dissertation first compares the clinical, viral and shedding dynamics of four modes of infection: Intramuscular (IM), Intranasopharyngeal (INP), Intraoropharyngeal (IOP), and Direct contact (DC), which are commonly used in ASFV investigation. This determines if different inoculation routes/dosages alter the pathogenesis of ASFV in swine and which route most closely resembles natural infection. While developing a standard infection model, a secondary aim of the project was to further clarify the events of infection by detailed characterization of the tissues and cells at different stages of disease. This was investigated in a bipartite approach, both in vivo and in vitro, utilizing virologic and molecular detection methods, as well as immunomicroscopic detection and localization of ASFV antigen alongside cellular markers of interest. Comparison of infection routes revealed that INP simulated natural infection while maintaining reproducibility and ease of control of variables. Examination of an extensive array of postmortem tissue samples revealed low and somewhat route-dictated detection of ASFV at previremic stages of infection, and systemic dissemination of the virus once viremia occurred. Microscopic analysis of tissues indicated that infected cells were distributed within interfollicular regions of lymphoid tissue and the interstitium of non-lymphoid tissue. Immunomicroscpic characterization determined that cells in which ASFV antigen was detected were predominately of monophagocytic origin, with high but variable expression of CD172a, CD163 and lower yet noteworthy expression of CD203a and sialoadhesin. This dissertation presents a comprehensive examination of ASF challenge models, necessary for the prospective standardization of live-animal ASF research. Furthermore, the distinctive characterization of ASFV-infected tissue and cells contribute to the growing understanding of the microenvironment required for the disease. Knowing what tissues and cell types are infected by ASFV can contribute to understanding the molecular or immunologic pathways involved, which viral genes/proteins are necessary for cellular infection. Ultimately this can lead to better targeting of prophylaxis or treatments for ASF."--Pages ii-iii.
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