Investigating CRESS DNA Viruses in Carnivores with emphasis on the family Circoviridae: Insights and Implications

The present thesis provides original data on the study of the molecular, epidemiological and phylogenetic patterns of CRESS DNA viruses and in particular of the members of the Circoviridae family in carnivores. The thesis was structured into chapters, in the format of a ‘thesis by publication’, encompassing articles published in international peer reviewed journals. Chapter 1 focuses on the investigation of CRESS DNA viruses in domestic carnivores. In Section 1.1 we describe a wide genetic diversity of Rep sequences of CRESS DNA viruses identified from feline samples. CanineCV-like sequences were identified from feline serum samples suggesting virus replication able to sustain viremia in cats. Moreover, the identification of a novel circovirus species named as feline Circovirus 1 (FeCV-1) was reported in cats in Italy. In Section 1.2 we evaluate the circulation of canine circovirus in dogs infected with canine parvovirus in Iran. Phylogenetic analysis showed that the Iranian CanineCV strains were more closely related to strains detected in Turkey. We provide new insights on the CanineCV’s molecular epidemiology and its role as a co-infection agent. Chapter 2 focuses on the detection of CRESS DNA viruses in wild carnivores. In Section 2.1 we describe the CAdV-1 and CanineCV circulation in wild carnivore populations in Italy. We report the detection of CanineCV in wolves and badgers and the first detection of cycloviruses in wolves in co-infection with CanineCV. In Section 2.2 we report the identification of a novel circovirus in the Iberian lynx population from different areas of Spain. The virus, termed ILCV-1, was repeatedly identified in the spleen samples, suggesting virus ability to replicate and spread actively in the host.