Comparative Pathology of African Swine Fever in Domestic Pigs and Wild Boar: insights from Experimental and Natural Infections

African swine fever (ASF), caused by African swine fever virus (ASFV), continues to spread globally, with European wild boar serving as a major reservoir and driver of viral transmission in Europe and Asia. This thesis comparatively evaluates disease dynamics, pathogenesis, macroscopic and histopathologic lesions, and viral antigen distribution in domestic pigs (Sus scrofa domesticus) and European wild boar (Sus scrofa scrofa) following intranasal inoculation with the highly virulent genotype II strain “Armenia 2007”. It contrasts these findings with naturally infected wild boar from field outbreaks. In the experimental infection, wild boar showed shorter incubation periods, earlier onset of clinical signs, earlier viremia, and faster systemic viral spread than domestic pigs. The medial retropharyngeal lymph nodes were key early replication sites in both subspecies, with viral antigen appearing earlier in wild boar, from 3 days post‑infection (pi). Despite reaching humane endpoints earlier, day 6 vs. 9 pi, wild boar showed less severe and extensive macroscopic and histopathological lesions and lower levels of viral antigen in tissues, even though viral antigen appeared and increased earlier, and lesions also began and progressed sooner. These results suggest a reduced tolerance to tissue damage rather than a lower pathogenic potential of the virus in wild boar. While naturally infected wild boar also exhibited lesions consistent with ASF, these were often more severe and heterogeneous than those observed in experimental animals. Lesions in naturally infected wild boar reflect a longer disease course and concurrent comorbidities. Overall, these results demonstrate clear differences in host responses between domestic pigs and wild boar and underscore the influence of both host-specific and environmental factors on disease expression and progression. Collectively, the findings provide important insights for improving surveillance, informing control measures, and for vaccine development in both domestic and wild suid populations. Keywords: African swine fever virus (ASFV), domestic pigs, wild boar, Sus scrofa, clinical course, disease outcome, macroscopic and histologic lesions evolution, virus dynamics, virus antigen distribution, natural infection.