Table 1.

Comparison of WNV and USUV main characteristics. Some important features of West Nile Virus (WNV) and Usutu Virus (USUV) are listed here, with the corresponding bibliographical references.

	WNV	USUV
Geographical Distribution	Africa, Europe, Middle East, North America and West Asia	Africa, Europe
Main Vector	Culex spp.	Culex spp.
Putative Seconday Vector	A. vexans [98], A. japonicus [99], A. albopictus [100]	A. albopictus [45,50]
Amplifying Host	Migratory birds	Migratory birds
Main Route of Transmission	Mosquito bite	Mosquito bite
Alternate Route of Transmission	Rare cases of contamination through organ transplant and transfusion [101] and of mother-to-child transmission [102]	Not described
Sensitivity to IFN	Strong [88]	Very strong [88]
Antagonism of IFN Response	Through NS4B [103]	Not described