Reads were also assembled de novo using Megahit [6], with the virus genome identified based on the blast procedure described above. To validate the assembled genome sequences, reads were subsequently mapped to the genomes and a majority consensus sequences were determined for each sample. Minor variation calling was performed after mapping using Genious software package, with a minimum coverage set to 20 and minimum variant frequency set to 0.05. In addition to mapping, the virus genomes were also confirmed with Sanger sequencing using primers designed based on the NGS sequences.