Full-length viral genome sequencing is key for virus distribution profiling, new virus discovery, and understanding virus populations across different samples. Circular DNA Enrichment Sequencing (CIDER-Seq) allows unbiased enrichment and long-read sequencing of circular DNA viruses. CIDER-Seq produces single-read full-length virus genomes, combining PCR-free enrichment with Single Molecule Real-Time sequencing and de-concatenation algorithm. CIDER-Seq data analysis package, using the DeConcat algorithm, processes PacBio sequencing data into intact circular DNA sequences, generating fully annotated and highly accurate circular DNA virus genome sequences.