Putative New West Nile Virus Lineage

West Nile virus (WNV) is becoming more widespread and markedly effecting public health. We sequenced the complete polyprotein gene of a divergent WNV strain newly detected in a pool of Uranotaenia unguiculata mosquitoes in Austria. Phylogenetic analyses suggest that the new strain constitutes a ninth WNV lineage or a sublineage of WNV lineage 4. West Nile virus (WNV), the most widespread flavivi-rus, is distributed throughout Africa, Asia, Europe, and Australia, and since 1999, WNV has also been present in the Americas (1). Within the last 2 decades, WNV infec-tion has caused an increasing number of cases of neuroin-vasive disease in humans and become a substantial public health problem (1). Up to 8 lineages of WNV, based on genetic differenc-es, have been proposed (1,2) (Table 1). Lineage 1 is widely distributed and further divided into lineage 1a, which in-cludes the American strains; lineage 1b, which is also re-ferred to as Kunjin virus and mainly described in Australia; and lineage 1c, which is also referred to as lineage 5 and comprises isolates from India. Lineage 2 has been detected in Africa and several parts of Europe, lineage 3 (Rabens-burg virus) has been isolated only in the Czech Republic, and lineage 4 has been reported from Russia (3). A putative sixth lineage, based on a small genome fragment, has been described from Spain (4), and putative lineages 7 (Koutan-go virus) and 8 have been reported from Senegal (2). WNV is maintained in an enzootic cycle between mos-quitoes and wild birds (1). In 2013, ≈100 Uranotaenia un-guiculata Edwards, 1913, mosquitoes were trapped during mosquito-monitoring projects at Lake Neusiedl-Seewinkel National Park in Austria and near Sedlec in the Czech Re-public. In Russia, Ur. unguiculata mosquitoes have been described as hosting lineage 4 WNV strains (A. Platonov, unpub. data) (GenBank accession nos. FJ154906–49 and FJ159129–31). To determine whether Ur. unguiculata mosquitoes in Austria and the Czech Republic also host WNV, we investigated the mosquitoes collected in 2013 for the presence of WNV, focusing on lineage 4 viruses