Usutu virus: current knowledge and future perspectives

Figures & data

Figure 1 Usutu virus phylogram trees.

Notes: (A) Representative phylogram showing the genetic relatedness between different flaviviruses. Accession numbers are displayed in the tree. The scale indicates 0.8 nucleotide substitutions/site. (B) Representative phylogram showing the genetic relatedness between geographically and temporally different Usutu virus strains. Accession numbers, country, and collection date are displayed in the tree. The scale indicates 0.2 nucleotide substitutions/site. The trees were based on complete genome sequence, built from a multiple alignment using Clustal omega and Phylogeny.fr.

Figure 2 Schematic view of the genomic organization of USUV.

Notes: The single ORF (boxes) that encodes both structural (C-prM/M and E) and NS proteins (NS1, NS2A, NS2B, NS3, NS4A, NS4B, and NS5) is flanked by two UTRs.
Abbreviations: C, capsid; E, envelope; ORF, open reading frame; prM/M, pre-membrane/membrane; USUV, Usutu virus; UTRs, untranslated regions.

Figure 3 Transmission electron microscopy of USUV RSPs and virions.

Notes: (A) Negative stained TEM image of purified Usutu RSPs. (B) Negative stained TEM image of Vero cells infected with USUV showing VP and electron-dense Vi.
Abbreviations: RSPs, recombinant subviral particles; TEM, transmission electron microscopy; USUV, Usutu virus; VP, vesicle packets; Vi, virions.

Figure 4 Confocal image of Vero cell transfected with the autophagosome marker GFP-LC3 plasmid and infected with USUV (red).

Note: Green LC3 aggregates indicate the induction of autophagy in the cell.
Abbreviation: USUV, Usutu virus.

Table 1 Circulation of USUV among avian species in Europe

Order	Common name	Scientific name	Country	References
Passeriformes	Blackbird	Turdus merula	Austria	62, 71, 72
			Hungary	70
			Switzerland	76
			Italy	14, 54, 79, 80
			Germany	82, 83
			Czech Republic	86
	Barn swallow	Hirundo rustica	Austria	72
	Black redstart	Phoenicurus ochruros	Austria	72
	Blue tit	Parus caeruleus	Switzerland	76
			Germany	82
	Canary	Serinus canaria domestica	Germany	82
	Common reed bunting	Emberiza schoeniclus	Austria	72
	Common starling	Sturnus vulgaris	Italy	14
			Germany	82
	Eurasian blackcap	Sylvia atricapilla	Austria	72
	Eurasian bullfinch	Pyrrhula pyrrhula	Belgium	85
	Eurasian jay	Garrulus glandarius	Austria	72
			Italy	54, 71
	Eurasian nuthatch	Sitta europaea	Austria	71, 72
	European greenfinch	Carduelis chloris	Switzerland	76
	European pied flycatcher	Ficedula hypoleuca	Austria	72
	European robin	Erithacus rubecula	Austria	71, 72
			Switzerland	76
	Garden warbler	Sylvia borin	Austria	72
	Great tit	Parus major	Austria	71, 72
	Hooded crow	Corvus cornix	Austria	72
	House martin	Delichon urbica	Austria	72
	House sparrow	Passer domesticus	Switzerland	76
			Germany	82
	Jackdaw	Corvus monedula	Austria	72
	Lesser whitethroat	Sylvia curruca	Austria	72
	Magpie	Pica pica	France	69
			Italy	54
	Redstart	Phoenicurus phoenicurus	Germany	73
	Reed warbler	Acrocephalus scirpaceus	Austria	72
	Song thrushes	Turdus philomelos	Spain	12
			Germany	83
			Austria	71, 72
	Whitethroat	Sylvia communis	Austria	72
Strigiformes	Barn owl	Tyto alba	Austria	72
	Eagle owl	Bubo bubo	Austria	72
	Hawk owl	Surnia ulala ulala	Switzerland	76
	Great gray owl	Strix nebulosa lapponica	Switzerland	76
			Germany	82 83
	Long-eared owl	Asio otus	Austria	72
			Italy	54 79, 80
			Germany	83
	Northern hawk-owl	Surnia ulula	Germany	83
	Pygmy owl	Glaucidium passerinum	Switzerland	76
	Snowy owl	Nyctea scandiaca	Switzerland	76
	Tawny owl	Strix aluco	Austria	72
	Tengmalm’s owl	Aegolius funereus	Switzerland	76
	Ural owl	Stix uralensis	Austria	72
Galliformes	Chickens	Gallus gallus domesticus	Italy	67, 68
	Common pheasants	Phasianus colchicus	Spain	81
			Austria	72
	Indian peafowl	Pavo cristatus	Austria	72
	Red-legged partridges	Alectoris rufa	Spain	81
			Italy	54
Accipitriformes	Osprey	Pandion haliaetus	Germany	73
	Beared vulture	Gypaetus barbatus	Austria	72
	Marsh harrier	Circus aeruginosus	Austria	72
Anseriformes	Mute swan	Cygnus olor	Serbia	84
	Mallard	Anas platyrhynchos	Italy	80
Charadriiformes	Black-headed gull	Larus ridibundus	Poland	74
	Inca tern	Larosterna inca	Germany	83
Ciconiiformes	White stork	Ciconia ciconia	Germany	73
Columbiformes	Eurasian collared dove	Streptopelia decaocto	Austria	72
			Italy	54
	Rock pigeon	Columba livia	Italy	80
Caprimulgiformes	Nightjar	Caprimulgus europaeus	Italy	54
Coraciiformes	Common kingfisher	Alcedo atthis	Germany	82
Falconiformes	Krestel	Falco tinnunculus	Austria	72
Gruiformes	Common coot	Fulica atra	Czech Republic	75
Piciformes	European green woodpecker	Picus viridis	Germany	83
	Great spotted woodpecker	Dendrocopos major	Austria	72
			Belgium	85

Abbreviation: USUV, Usutu virus.

Figure 5 Map showing the spread of Usutu across Europe from 2002 to 2016.