First detection and genomic characteristics of bovine torovirus in dairy calves in China

Abstract

Bovine torovirus (BToV) is a diarrhea-causing pathogen. In this study, 92 diarrheic fecal samples from five farms in four provinces in China were collected and tested for BToV using a RT-PCR assay, and 21.73% samples were found to be BToV positive. Moreover, two complete BToV genome sequences (MN073058 and MN073059) were obtained from the clinical samples, which were 28,297 and 28,301 nucleotides in length, respectively. Sequence analysis showed that the two isolates shared 10 identical amino acid mutations in the S protein compared to the complete S sequences of BToV available in the GenBank database. In addition, seven consecutive amino acid mutations were found from aa 1,486 to 1,492 in the S protein of isolate MN073058. Moreover, the two isolates shared one identical amino acid mutation in the receptor binding sites of the HE protein. To the best of our knowledge, this is the first report on the epidemic and genomic characterization of BToV in China, which is helpful for further understanding the genetic evolution of BToV.

Development and use of a reverse transcription insulated isothermal PCR assay for detection and characterization of bovine torovirus in yaks

“…BToV is an important diarrhea-causing pathogen that has been detected in China, Japan, Turkey, Italy, Brazil, America, South Africa, and other countries [ 1 , 3 , 5 , 6 , 8 , 15 , 28 ]. In this study, we developed a new RT-iiPCR assay for the detection of BToV based on the portable, commercially available POCKIT TM device.…”

“…BToV-positive samples were used to simultaneously amplify the complete S and HE genes. The primer information is presented elsewhere [ 6 ]. All amplification products were purified and cloned into PMD19 Simple T Vector (TaKaRa Bio, Inc.) for sequencing, and the resulting sequences were assembled using SeqMan software (version 7.0; DNASTAR, Madison, WI, USA).…”

“…The HE protein contains three functional domains: a lectin domain (R), an esterase domain (E), and a membrane-proximal domain (MP), and the R and E domains may be important for virus entry [ 14 ]. Based on their HE gene sequences, BToVs can be classified into three genotypes (I-III) [ 15 ], with genotypes II and III being the most prevalent [ 6 ]. The M protein functions in BToV assembly and nucleocapsid recognition [ 10 ].…”

Recent Progress in Torovirus Molecular Biology

“…Because natural and experimental infection by BToV causes diarrhoea in calves [ 2 , 20 , 25 , 26 ] and may be associated with respiratory symptoms [ 27 ], most clinical and pathogenic data on ToV were obtained from BToV [ 9 , 13 ]. BToV has been detected on all five continents [ 19 , 21 , 22 , 23 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 ], and a serological survey indicated that most adult cattle are seropositive [ 13 , 16 , 19 , 20 , 46 ].…”

“…There is much evidence for heterologous and homologous recombination of ToVs. A full-length genome analysis of recent Japanese BToV indicated interspecies recombination between BRV-like BToV and PToV at the 3’-ends of ORF1b and the HE gene ( Figure 3 a) [ 23 , 42 ]. An identical recombinant breakpoint in HE was found in European BToVs isolated in the late 1990s [ 89 ], suggesting that European and Japanese BToVs share a common ancestor.…”