Characterization and phylogenteic analysis of Usutu virus isolates in Sardinia

Flaviviruses are Arbovirus, a group of viruses able to propagate both in Arthropodes and in Vertebrates, including human. Upon infection, human can develop a variety of signs such as encephalitis, meningitis and fever. Natural transmission cycle occurs between ornithophilic mosquitoes (vector) and birds that serve as reservoir or amplifying host. Our study focuses on the Usutu virus (USUV). USUV is an enveloped virus with a protein capside enclosing a positive-strand RNA genome with a size of about 11 kb. USUV was detected in Sardinia for the first time in 2013. Aim of the project is to detect USUV circulating in Sardinia through the screening of pools of mosquitoes caught with dedicated traps, and the monitoring of wild and sinanthropic birds. Viral full genomic sequencing through the technique of “primer-walking” with home designed primers is performed on viral variants obtained from positive samples. Viral strains molecular characterization and phylogenetic analysis is also performed by using dedicated software. Local strains are closely related to Italian strains and in particular with “Bologna 2009". We obtained the complete genome sequences of the isolates designated strains “91418_Sassari2013” and “62059_Sardegna2015”. We found some important molecular features, more of them associate with increase of virulence and capacity to infect mammals includes humans. Results have implications in the molecular epidemiology of Usutu virus in the Mediterranean area and in the study of pathogenicity of this Flavivirus.