Dudar L. Molecular and biological characteristics of porcine circovirus type 2 isolates identified in Ukraine

The dissertation is devoted to the study, identification of porcine circovirus type 2 isolates in Ukraine, the dynamics of its spreading, as well as to the clarification of phylogenetic features and evolution connections between Ukrainian isolates, detected from swine in production herds and wild animals. Moreover, total diagnostics approach has been developed for differentiation of all PCV2-associated diseases of swine. For the first time, Porcine Circovirus type 2 was identified in 20 of 24 regions of Ukraine and Crimea. The assessment of the spread of the virus has been carried out, which allows us to assert that the level of distribution of PCV2 in Ukraine reaches 41%. With the aim of detection of all expected genotypes of PCV2 strains, the new PCR-based test-system was developed and approved. Phylogenetic analysis of Ukrainian isolates of PCV2 showed the belonging of viruses to group 1 (PCV2-1a\b) and group 2 (PCV2-2b). The established evolutionary relationships between isolates, detected from pigs in swine herds and wild boars from the same regions of Ukraine indicate that most of them have different origins and belong to different subgroups. However, isolates from the Kharkiv oblast’ are highly homologous, which may be due to the direct transfer of PCV2 between wild boars and farm animals. An approach for the comprehensive diagnosis of all PCV2-associated diseases, which combines the results obtained by Real Time PCR with the data of histological and immunohistochemical analysis, is developed. For the reason of quick and routine laboratory detection of PCV2 in different tissues and pathological materials, effective and potential RT-PCR approach was developed and confirmed by trials. At the same time, huge histological investigations were used for differentiation of most PCV2-associated diseases, specific morphological and pathological changes were described that should be used for diagnosis confirmation. Moreover, this comprehensive approach has been added by immunohistochemistry tool for antigen presence visualization in cases when histological changes are absent. The developed approach covers all PCV2-associated diseases and can be implemented and used in diagnostics laboratory.