title: Molecular epidemiology of bluetongue virus in Portugal during 2004-2006 outbreak.
abstract: After 44 years of epidemiological silence, bluetongue virus (BTV) was reintroduced in Portugal in the autumn of 2004. The first clinical cases of bluetongue disease (BT) were notified in sheep farms located in the South of Portugal, close to the Spanish border. A total of six BTV, five of serotype 4 and one of serotype 2 were isolated from sheep and cattle during the 2004-2006 epizootics. The nucleotide sequence of gene segments L2, S7 and S10 of BTV-4 prototype strain (BTV4/22045/PT04) obtained from the initial outbreak and of BTV-2 (BTV2/26629/PT05) was fully determined and compared with those from other parts of the world. The phylogenetic analysis revealed that BTV4/22045/PT04 is related to other BTV-4 strains that circulate in the Mediterranean basin since 1998, showing the highest identity (99%) with BTV-4 isolates of 2003 from Sardinia and Corsica, whereas BTV2/26629/PT05 is almost indistinguishable from the Onderstepoort BTV-2 live-attenuated vaccine strain and its related field strain isolated in Italy. Since live-attenuated BTV-2 vaccine was never used in Portugal, the isolation of this strain may represent a natural circulation of the vaccine virus used in other countries in Mediterranean Europe.
authors.affiliation: Laboratório Nacional de Investigação Veterinária, Estrada de Benfica 701, 1549-011 Lisboa, Portugal.
authors.forename: Sílvia C
authors.initials: SC
authors.lastname: Barros
authors.forename: Fernanda
authors.initials: F
authors.lastname: Ramos
authors.forename: Tiago M
authors.initials: TM
authors.lastname: Luís
authors.forename: Andreia
authors.initials: A
authors.lastname: Vaz
authors.forename: Margarida
authors.initials: M
authors.lastname: Duarte
authors.forename: Margarida
authors.initials: M
authors.lastname: Henriques
authors.forename: Benedita
authors.initials: B
authors.lastname: Cruz
authors.forename: Miguel
authors.initials: M
authors.lastname: Fevereiro
mesh_terms: D000818:Animals; D001483:Base Sequence; D001819:Bluetongue / Q000453:epidemiology* / Q000821:virology*; D001820:Bluetongue virus / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D002417:Cattle; D002418:Cattle Diseases / Q000453:epidemiology* / Q000821:virology; D002460:Cell Line; D002642:Chick Embryo; D004196:Disease Outbreaks / Q000662:veterinary; D017720:Molecular Epidemiology; D008969:Molecular Sequence Data; D010802:Phylogeny; D011174:Portugal / Q000453:epidemiology; D012367:RNA, Viral / Q000737:chemistry; D016415:Sequence Alignment; D012703:Serotyping / Q000662:veterinary; D012756:Sheep; D013047:Specific Pathogen-Free Organisms
chemical_list: D012367:RNA, Viral