Fig. 2.

Sequence of events in the molecular detection of viruses: (A) Samples processed by hybridisation or PCR require steps to enrich for virus before amplified products are sequenced and identified. Enrichment may result in decreased assay sensitivity, and amplification can generate bias towards a dominant sequence; (B) Transcriptome subtraction methods can be performed without enrichment or amplification with direct sequencing of nucleic acids extracted from a sample of interest. Subsequent subtraction of resulting sequences from databases facilitates virus identification.