SBV Culicoides (BO-20-009-016)

Biting midges of the genus Culicoides have been demonstrated to be responsible for the transmission of Schmallenbergvirus (SBV) among cattle and sheep in the outbreak in Europe which started in late summer. Determination of the species identity of field-collected midges from the Netherlands in August–September 2011 using DNA analysis of the 18S internal transcribed spacer 1 (ITS1) revealed that SBV was only harbored in 3 species: Culicoides scoticus, C Culicoides chiopterus, and Culicoides obsoletus sensu stricto [1]. Five SBV-positive pools of midges (3 C. scoticus, 1 C. obsoletus sensu stricto, and 1 undeterminable) that scored an rRT-PCR Ct-value lower than 25 in heads of the midges were used to generate cDNA fragments covering regions of the L, M and S genomic RNA segments (~150-300 bp in length). A considerable genetic variation was observed in these regions between different SBV isolates origination from cattle and lambs. For further comparison of SBV sequences originating from midges and SBV sequences originating from cattle  L, M, and S cDNA preparations generated for each pool of midges were tagged with a unique index-sequence as identifier, and all indexed midge pools were mixed and sequenced in a single Illumina Miseq run.