Detection of negative stranded RNA of DWV. Negative stranded RNA of DWV was detected in six (lanes 5, 8, 12-15) out of 15 SHB that were fed on infected honeybee workers and previously identified as being DWV positive by RT-PCR assay (lane 1: 100-bp DNA ladder; lane 17: negative control). No positive control was included in the assay to exclude the possible chance of contamination. The specificity of individual PCR bands was confirmed by sequencing.