Evidence of West Nile virus lineage 2 circulation in Northern Italy

Istituto G. Caporale Teramo, Via Campo Boario, 64100 Teramo, Italy.
Veterinary Microbiology (Impact Factor: 2.51). 02/2012; 158(3-4):267-73. DOI: 10.1016/j.vetmic.2012.02.018
Source: PubMed


A West Nile virus (WNV) strain belonging to lineage 2 was for the first time detected in two pools of Culex pipiens collected in the province of Udine and in tissues of a wild collared dove (Streptopelia decaocto) found dead in the province of Treviso, in North East of Italy. It was molecularly identified by group and WNV lineage specific RT-PCRs and characterized by partial sequencing of the NS3 and NS5 genes. When compared with the sequences of same fragments of NS3 and NS5 of the WNV lineage 2 strain isolated from birds of prey in Hungary (2004), the phylogenetic analysis of these sequences revealed 100% and 99% similarity, respectively. As the Hungarian strain, the NS3 selected sequence differed from the 2010 Greek isolate by one amino-acid located at 249 site which is the site involved in genetic modulation of WNV pathogenicity. The Italian and Hungarian strains have histidine rather than proline at this site. The presence of a lineage 2 strain in regions where the lineage 1 strain is still circulating, creates a new scenario with unpredictable consequences. In this situation comprehensive investigations on the occurrence, ecology, and epidemiology of these different WNV strains circulating in Italy become the highest priority.

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    • "During 2011 in Italy the WNV caused several outbreaks among horses and birds. Lineage 2 strain was found in two pools of Culex pipiens collected in Friuli-Venezia Giulia region and in the tissues of a resident collared dove (Streptopelia decaocto) found dead in Veneto region, in northeast Italy [80]. During the summer of 2011, WNV lineage 2 was also detected in urine samples of a febrile patient in Marche region [81] and in a patient coming from northeastern Sardinia. "
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    • "WNV infections have been described in a wide variety of vertebrates (Komar et al., 2003). The virus is maintained in an enzootic cycle between ornithophilic mosquitoes, mainly of the Culex genus (Hayes et al., 2005; Ziegler et al., 2012), but also Aedes and Ochlerotatus genera and certain species of wild birds (Savini et al., 2012; Ziegler et al., 2012). WNV was found in more than 150 species of wild and domestic birds (van der Meulen et al., 2005). "
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    • "No further clinical manifestations of WNV were reported until 2008, when 251 horse premises tested positive for WNV in the Po Valley of north-eastern Italy [15]. Since then WNV has been recurrently detected in horses, wild birds, and humans [16,17], suggesting the likely endemisation of the disease [18]. In 2010, WNV was also identified in Culex pipiens mosquitoes in the neighbouring regions of Veneto and Emilia Romagna. "
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