Towards Efficient Early Warning: Pathobiology of African Swine Fever Virus “Belgium 2018/1” in Domestic Pigs of Different Age Classes

SIMPLE SUMMARY: African swine fever (ASF) is a devastating viral disease of both wild boar and domestic pigs. Historically, the disease was mainly found in Sub-Saharan Africa. However, after the introduction of ASF into Georgia in 2007, the fatal disease spread to many European and Asian countries. In the absence of vaccines or treatment options, early detection of disease incursions is of paramount importance to limit the impact on animal health and pig industry. Thus, the biological characteristics of circulating virus strains must be known and communicated to practitioners and official veterinarians. Along these lines, the ASFV strain found in Belgium in 2018 was further characterized for its disease course in young and subadult domestic pigs. In general, clinical and pathological findings were in line with previous experiments utilizing highly virulent ASFV genotype II strains. However, in one of our experimental infections, four out of eight subadult domestic pigs showed milder signs and recovered, which was unexpected and points to an age dependency of clinical signs that could impact the early recognition of ASF incursions. We hope that communication of the available data will help practical and official veterinarians in the field to detect ASF as early as possible and thus minimize its impact. ABSTRACT: African swine fever (ASF) is one of the most important and devastating viral diseases in wild boar and domestic pigs worldwide. In the absence of vaccines or treatment options, early clinical detection is crucial and requires a sound knowledge of disease characteristics. To provide practitioners and state veterinarians with detailed information, the objective of the present study was to characterize the ASF virus (ASFV) isolate “Belgium 2018/1” in subadult and weaning domestic pigs. To this end, two animal trials were performed. Trial A included eight subadult domestic pigs and trial B five weaner pigs. In general, clinical signs and pathological lesions were in line with previous studies utilizing highly virulent ASF genotype II viruses. However, in trial A, four subadult domestic pigs survived and recovered, pointing to an age-dependent outcome. The long-term fate of these survivors remains under discussion and would need further investigation.