title: Usutu virus in Italy: an emergence or a silent infection?
abstract: A two year study (2008-2009) was carried out to monitor the Usutu virus (USUV) circulation in Italy. Sentinel horses and chickens, wild birds and mosquitoes were sampled and tested for the presence of USUV and USUV antibodies within the WND National Surveillance plan. Seroconversion evidenced in sentinel animals proved that in these two years the virus has circulated in Tuscany, Emilia Romagna, Veneto and Friuli Venezia Giulia regions. In Veneto USUV caused a severe blackbird die-off disease involving at least a thousand birds. Eleven viral strains were detected in organs of 9 blackbirds (52.9%) and two magpies (0.5%) originating from Veneto and Emilia Romagna regions. USUV was also detected in a pool of Culex pipiens caught in Tuscany. According to the alignment of the NS5 partial sequences, no differences between the Italian USUV strains isolated from Veneto, Friuli and Emilia Romagna regions were observed. The Italian North Eastern strain sequences were identical to those of the strain detected in the brain of a human patient and shared a high similarity with the isolates from Vienna and Budapest. Conversely, there were few differences between the Italian strains which circulated in the North Eastern regions and the USUV strain detected in a pool of C. pipiens caught in Tuscany. A high degree of similarity at both nucleotide and amino acid level was also found when the full genome sequence of the Italian North Eastern isolate was compared with that of the strains circulating in Europe. The North Eastern Italian strain sequence exhibited 97% identity to the South African reference strain SAAR-1776. The deduced amino acid sequences of the Italian strain differed by 10 and 11 amino-acids from the Budapest and Vienna strains, respectively, and by 28 from the SAAR-1776 strain. According to this study two strains of USUVs are likely to have circulated in Italy between 2008 and 2009. They have developed strategies of adaptation and evolution to spread into new areas and to become established.
authors.affiliation: Istituto G. Caporale, Teramo, Italy. g.savini@izs.it
authors.forename: Giovanni
authors.initials: G
authors.lastname: Savini
authors.forename: Federica
authors.initials: F
authors.lastname: Monaco
authors.forename: Calogero
authors.initials: C
authors.lastname: Terregino
authors.forename: Annapia
authors.initials: A
authors.lastname: Di Gennaro
authors.forename: Luca
authors.initials: L
authors.lastname: Bano
authors.forename: Chiara
authors.initials: C
authors.lastname: Pinoni
authors.forename: Roberta
authors.initials: R
authors.lastname: De Nardi
authors.forename: Paolo
authors.initials: P
authors.lastname: Bonilauri
authors.forename: Monica
authors.initials: M
authors.lastname: Pecorari
authors.forename: Luigina
authors.initials: L
authors.lastname: Di Gialleonardo
authors.forename: Lebana
authors.initials: L
authors.lastname: Bonfanti
authors.forename: Andrea
authors.initials: A
authors.lastname: Polci
authors.forename: Paolo
authors.initials: P
authors.lastname: Calistri
authors.forename: Rossella
authors.initials: R
authors.lastname: Lelli
mesh_terms: D000818:Animals; D000835:Animals, Wild / Q000821:virology*; D000914:Antibodies, Viral / Q000097:blood; D002645:Chickens / Q000821:virology; D003465:Culex / Q000821:virology*; D005416:Flavivirus / Q000235:genetics / Q000302:isolation & purification*; D018177:Flavivirus Infections / Q000453:epidemiology* / Q000662:veterinary* / Q000821:virology; D016679:Genome, Viral; D005843:Geography; D006736:Horses / Q000821:virology*; D007558:Italy / Q000453:epidemiology; D046109:Passeriformes / Q000821:virology*; D012367:RNA, Viral / Q000235:genetics; D018571:Sentinel Surveillance / Q000662:veterinary; D017423:Sequence Analysis, RNA
chemical_list: D000914:Antibodies, Viral; D012367:RNA, Viral