title: Detection and isolation of Sindbis virus from mosquitoes captured during an outbreak in Sweden, 2013.
abstract: Mosquito-borne alphaviruses have the potential to cause large outbreaks throughout the world. Here we investigated the causative agent of an unexpected Sindbis virus (SINV) outbreak during August-September, 2013, in a previously nonendemic region of Sweden. Mosquitoes were collected using carbon dioxide-baited CDC traps at locations close to human cases. The mosquitoes were initially screened as large pools by SINV-specific quantitative RT-PCR, and the SINV-positive mosquitoes were species determined by single-nucleotide polymorphism (SNP) analysis, followed by sequencing the barcoding region of the cytochrome oxidase I gene. The proportion of the collected mosquitoes was determined by a metabarcoding strategy. By using novel strategies for PCR screening and genetic typing, a new SINV strain, Lövånger, was isolated from a pool of 1600 mosquitoes composed of Culex, Culiseta, and Aedes mosquitoes as determined by metabarcoding. The SINV-positive mosquito Culiseta morsitans was identified by SNP analysis and sequencing. After whole-genome sequencing and phylogenetic analysis, the SINV Lövånger isolate was shown to be most closely similar to recent Finnish SINV isolates. In conclusion, within a few weeks, we were able to detect and isolate a novel SINV strain and identify the mosquito vector during a sudden SINV outbreak.
authors.affiliation: 1 Swedish Defence Research Agency, CBRN Defence and Security , Umeå, Sweden .
authors.forename: Joakim
authors.initials: J
authors.lastname: Bergqvist
authors.forename: Oscar
authors.initials: O
authors.lastname: Forsman
authors.forename: Pär
authors.initials: P
authors.lastname: Larsson
authors.forename: Jonas
authors.initials: J
authors.lastname: Näslund
authors.forename: Tobias
authors.initials: T
authors.lastname: Lilja
authors.forename: Cecilia
authors.initials: C
authors.lastname: Engdahl
authors.forename: Anders
authors.initials: A
authors.lastname: Lindström
authors.forename: Åsa
authors.initials: Å
authors.lastname: Gylfe
authors.forename: Clas
authors.initials: C
authors.lastname: Ahlm
authors.forename: Magnus
authors.initials: M
authors.lastname: Evander
authors.forename: Göran
authors.initials: G
authors.lastname: Bucht
mesh_terms: D018354:Alphavirus Infections / Q000453:epidemiology* / Q000821:virology; D000818:Animals; D001483:Base Sequence; D009033:Culicidae / Q000821:virology*; D058893:DNA Barcoding, Taxonomic; D004196:Disease Outbreaks; D016679:Genome, Viral / Q000235:genetics*; D006801:Humans; D008969:Molecular Sequence Data; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D012845:Sindbis Virus / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D013548:Sweden / Q000453:epidemiology
keywords: Barcoding; Isolation; Mosquito; Sindbis; Virus