Molecular characterization and phylogenetic analysis of the genome of porcine torovirus

Sun, Huan; Lan, Daoliang; Lu, Lifang; Chen, Molin; Wang, Changsong; Hua, Xiuguo

In this study, we amplified and sequenced the first genome of porcine torovirus (PToV SH1 strain). The genome was found to be 28,301 bp in length, sharing 79 % identity with Breda virus. It mainly consists of replicase (20,906 bp) and structural genes: spike (4,722 bp), membrane (702 bp), hemagglutinin-esterase (1,284 bp), and nucleocapsid (492 bp). Sequence alignments and structure prediction suggest genetic differences among toroviruses, mainly in NSP1 (papain-like cysteine proteinase domain). Rooted phylogenetic trees were constructed based on the 3C-like proteinase and RNA-dependent RNA polymerase genes. PToV, Berne virus and Breda virus were clustered together, forming a separate branch from white bream virus that was distant from that of the coronaviruses.