Complete genome analysis and molecular characterization of Usutu virus that emerged in Austria in 2001. Comparison with the South African Strain SAAR-1776 and other flaviviruses

Here we describe the complete genome sequences of two strains of Usutu virus (USUV), a mosquito-borne member of the genus Flavivirus in the Japanese encephalitis virus (JEV) serogroup. USUV was detected in Austria in 2001 causing a high mortality rate in blackbirds; the reference strain (SAAR-1776)...

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Bibliographic Details
Published in:Virology (New York, N.Y.) N.Y.), 2004-10, Vol.328 (2), p.301-310
Main Authors: Bakonyi, T, Gould, E.A, Kolodziejek, J, Weissenbock, H, Nowotny, N
Format: Article
Language:English
Subjects:
Amino Acid Sequence
Animals
Austria
Bird Diseases - virology
Birds
Brain - virology
Flaviviridae
Flavivirus
Flavivirus - genetics
Flavivirus - isolation & purification
Flavivirus Infections - veterinary
Flavivirus Infections - virology
Genome, Viral
Molecular Sequence Data
mosquito-borne diseases
Phylogeny
Polyproteins - genetics
Sequence Alignment
Sequence Homology
strain differences
Viral Proteins - genetics
wild birds
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Summary:Here we describe the complete genome sequences of two strains of Usutu virus (USUV), a mosquito-borne member of the genus Flavivirus in the Japanese encephalitis virus (JEV) serogroup. USUV was detected in Austria in 2001 causing a high mortality rate in blackbirds; the reference strain (SAAR-1776) was isolated in 1958 from mosquitoes in South Africa and has never been associated with avian mortality. The Austrian and South African isolates exhibited 97% nucleotide and 99% amino acid identity. Phylogenetic trees were constructed displaying the genetic relationships of USUV with other members of the genus Flavivirus. When comparing USUV with other JEV serogroup viruses, the closest lineage was Murray Valley encephalitis virus (nt: 73%, aa: 82%) followed by JEV (nt: 71%, aa: 81%) and West Nile virus (nt: 68%, aa: 75%). Comparison of the genomes showed that the conserved structural elements and putative enzyme motifs were homologous in the two USUV strains and the JEV serogroup. The factors that determine the severe clinical symptoms caused by the Austrian USUV strain in Eurasian blackbirds are discussed. We also offer a possible explanation for the origins and dispersal of USUV, JEV, and MVEV out of Africa.
ISSN:0042-6822
1096-0341
DOI:10.1016/j.virol.2004.08.005