Detection and molecular characterization of porcine toroviruses in Korea

Abstract

This study examined the prevalence and genetic diversity of the porcine torovirus (PToV) in Korea. Of 295 samples, 19 (6.4%) samples tested positive for PToVs by RT-PCR. A low nucleotide sequence identity of the partial S gene was detected among the Korean PToVs (73.5%) and between the Korean and European PToVs (74.0%). Phylogenetic analysis of the spike and nucleocapsid genes showed that the Korean PToVs form distinct branches with clusters corresponding to the farm of origin, which were separate from the other known foreign PToVs. These findings suggest that genetically diverse Korean PToV strains cause sporadic infections in Korea.

Development of universal SYBR Green real-time RT-PCR for the rapid detection and quantitation of bovine and porcine toroviruses

“…These findings support the above suggestion that SYBR Green real-time RT-PCR is more sensitive than conventional RT-PCR and nested PCR. In addition, these observations indicate that the fecal prevalence of BToV and PToV in calves and piglets might be higher than previously reported in South Korea (Park et al, 2008;Shin et al, 2010).…”

“…Porcine toroviruses were detected in 5% of the diarrhea specimens of piglets in Hungary (Matiz et al, 2002), 23.7% in Japan (Kiriwasa et al, 2007), and 6.4% in South Korea . Using the same South Korean bovine and porcine fecal samples (Park et al, 2008;Shin et al, 2010), SYBR Green realtime RT-PCR assay detected BToVs in 18.2% and PToVs in 36.0% of the samples. These findings support the above suggestion that SYBR Green real-time RT-PCR is more sensitive than conventional RT-PCR and nested PCR.…”

“…Toroviruses in calves and piglets have been identified in a number of outbreaks in bovine and porcine herds with severe and recurring diarrhea negative for routine virologic, bacteriologic and parasitologic agents (Hoet et al, 2003;Kiriwasa et al, 2007;Park et al, 2009;Shin et al, 2010). Interestingly, those fecal samples that tested positive only by SYBR Green real-time RT-PCR contained lower numbers of BToV and PToV RNA (3.4 × 10 2 -1.2 × 10 4 and 3.1 × 10 3 -3.9 × 10 4 viral copies per reaction, respectively).…”

“…The prevalence of BToVs and PToVs and their genetic properties in the diarrhea specimens of calves (n = 121) and piglets (n = 86) was reported previously (Park et al, 2008;Shin et al, 2010). Using the fecal samples, the detection rates of BToV and PToV by real-time RT-PCR were compared with those of conventional RT-PCR and nested PCR (Tables 2 and 3 (Tables 2 and 3).…”

“…Total recovered RNA was suspended in 50 l of RNase-free water and stored at −80 • C until analysis. The oligonucleotide primers, and conventional RT-PCR and nested PCR conditions for the detection of BToV and PToV (Table 1) were described previously (Park et al, 2008;Shin et al, 2010).…”