Evidence of West Nile virus lineage 2 circulation in Northern Italy

Vet Microbiol. 2012 Aug 17;158(3-4):267-73. doi: 10.1016/j.vetmic.2012.02.018. Epub 2012 Feb 17.


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.

MeSH terms

  • Animals
  • Bird Diseases / virology*
  • Birds
  • Culex / virology
  • Hungary
  • Italy
  • RNA Helicases / genetics
  • Sequence Homology, Nucleic Acid
  • Serine Endopeptidases / genetics
  • Viral Nonstructural Proteins / genetics
  • West Nile Fever / virology*
  • West Nile virus / classification*
  • West Nile virus / genetics*
  • West Nile virus / isolation & purification


  • NS3 protein, flavivirus
  • NS5 protein, flavivirus
  • Viral Nonstructural Proteins
  • Serine Endopeptidases
  • RNA Helicases