NGS analysis
A total of 1,735,463 sequencing reads were generated by the HiSeq sequencer from extracted viral total RNA, and yielding 376 Mb of fastq format sequenced data. After processed by quality control (QC) filters of the Hiseq platform, non-research target readings that were similar to mRNA or rRNA sequences were removed. The residual 231,327 clean reads were assembled by de novo assembly module of CLC Genomic Workbench software (version 10.0). Finally, one long contig that covered the full length of an astrovirus was generated by re-mapping the clean reads back to the astrovirus reference sequences. Whereas no other pathogen was discovered by analysing all assembled contigs.