Most human viruses cannot be detected due to unknown genome information. The objective of this study was to investigate unknown genomes selected (+)ssRNA viruses in wastewater. Metagenomic analysis targeting (+)ssRNA viruses in wastewater has found huge number of unknown sequence fragments, which implies presence of unknown human enteric viruses. We assembled contigs using the unknown fragments obtained from the selective metagenomic analysis of wastewater samples (n = 6). We additionally carried out detection of the contigs in the wastewater samples using quantitative reverse-transcription PCR (RT-qPCR) to confirm presence of genomes with the sequences of constructed contigs. The number of contigs with unidentified sequences from each wastewater sample was 4-27, and a total of 7 contigs with 114-1585 bases were further assembled as common contigs among multiple samples. All the common contigs were not assigned to any nucleotide sequence by BLASTn, and 3 out of them were aligned to the protein sequence of Laverivirus UC1 with low identities (38-60%) by BLASTx. One of the common contigs was detected in all the wastewater samples with the concentration ranging up to 2.8 logio copies/mL by the RT-qPCR. These results suggested the presence of unknown (+)ssRNA viruses in the samples. (196/200 words)
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