The central role of Italy in the spatial spread of USUTU virus in Europe.

USUTU virus (USUV) is an arbovirus maintained in the environment through a bird-mosquito enzootic cycle. Previous surveillance plans highlighted the endemicity of USUV in North-eastern Italy. In this work, we sequenced 138 new USUV full genomes from mosquito pools (Culex pipiens) and wild birds collected in North-eastern Italy and we investigated the evolutionary processes (phylogenetic analysis, selection pressure and evolutionary time-scale analysis) and spatial spread of USUV strains circulating in the European context and in Italy, with a particular focus on North-eastern Italy. Our results confirmed the circulation of viruses belonging to four different lineages in Italy (EU1, EU2, EU3 and EU4), with the newly sequenced viruses from the North-eastern regions, Veneto and Friuli Venezia Giulia, belonging to the EU2 lineage and clustering into two different sub-lineages, EU2-A and EU2-B. Specific mutations characterize each European lineage and geographic location seem to have shaped their phylogenetic structure. By investigating the spatial spread in Europe, we were able to show that Italy acted mainly as donor of USUV to neighbouring countries. At a national level, we identified two geographical clusters mainly circulating in Northern and North-western Italy, spreading both northward and southward. Our analyses provide important information on the spatial and evolutionary dynamics of USUTU virus that can help to improve surveillance plans and control strategies for this virus of increasing concern for human health.

Cross-clade protection against H5N1 HPAI strains recently isolated from commercial poultry in Egypt with a single dose of a baculovirus based vaccine.

The current avian influenza epidemic in Egypt caused by circulation of genetically and antigenically diverse H5N1 HPAI viruses in poultry is controlled by applying vaccination among other measures. In this context, the use of a DIVA (differentiating infected from vaccinated animals) vaccination strategy utilizing a vaccine capable of inducing protection against multiple antigenic variants may result as an additional control tool to the existing ones. In this study the efficacy of a single-shot recombinant baculovirus-based vaccine in specific-pathogen-free chickens was tested by experimental challenge with genetically and antigenically diverse H5N1 HPAI viruses belonging to clades 2.2.1 and 2.2.1.1, which have been circulating in Egypt since 2010. A single dose of vaccine, administration at 10 days of age, was shown to confer 100% clinical protection, with a decrease or suppression of virus shedding.