Porcine Sapovirus (SaV) was first identified by electron microscopy in the United States in 1980 and has since been reported from both asymptomatic and diarrheic pigs usually in mixed infection with other enteric pathogens. SaV as the sole etiological agent of diarrhea in naturally infected pigs has not previously been reported in the United States. Here, we used four independent lines of evidence including metagenomics analysis, real-time RT-PCR (rRT-PCR), histopathology, and in situ hybridization to confirm porcine SaV genogroup III (GIII) as the sole cause of enteritis and diarrhea in pigs. A highly sensitive and specific rRT-PCR was established to detect porcine SaV GIII. Examination of 184 fecal samples from the outbreak farm showed that pigs with clinical diarrhea had significantly lower Ct values (15.9 ± 0.59) compared to clinically unaffected pigs (35.8 ± 0.71). Further survey of 336 fecal samples from different states in the United States demonstrated that samples from pigs with clinical diarrhea had a comparable positive rate (45.3%) with those from non-clinical pigs (43.1%). However, the SaV-positive pigs with clinical diarrhea had significantly higher viral loads (Ct = 26.0 ± 0.5) than those positive but clinically healthy pigs (Ct = 33.2 ± 0.9). Phylogenetic analysis of 20 field SaVs revealed that all belonged to SaV GIII and recombination analysis indicated that intra-genogroup recombination occurred within the field isolates of SaV GIII. These results suggest that porcine SaV GIII plays an important etiologic role in swine enteritis and diarrhea and rRT-PCR is a reliable method to detect porcine SaV. Our findings provide significant insights to better understand the epidemiology and pathogenicity of porcine SaV.

Shiga toxin-producing Escherichia coli (STEC) is an important foodborne pathogen capable of causing severe gastrointestinal diseases in humans. Cattle and sheep are the natural reservoir hosts of STEC strains. Previously, we isolated 56 STEC strains from anal and carcass swab samples of cattle and sheep in farms and slaughterhouses. In this study, we performed whole-genome sequencing of these isolates and determined their serotypes, virulence profiles, sequence types (STs), and genetic relationships. Our results showed that the 56 isolates belong to 20 different STs, 29 O:H serotypes, and 8 stx subtype combinations. The highly prevalent serotypes were O8:H25 and O87:H16 for bovine and ovine isolates, respectively. Five serotypes of cattle or sheep isolates are novel. The majority (63%) of cattle isolates contain stx1+stx2, subtyped into stx1a, stx2a, and stx2c. In contrast, most of the sheep isolates contain stx1 only, primarily subtyped into stx1a and stx1c. None of the isolates tested eae-positive, but virulence factors such as ehxA and espP were present with variable prevalence rates. The prevalence of saa (19.6%) and espP (12.5%) in cattle isolates is much higher than that in sheep isolates, whereas that of subA (34%), katP (14.3%), and ireA (28.6%) in sheep isolates is considerably higher than that in cattle isolates. Core-genome SNP analysis revealed that the majority of isolates could be clustered based on their serotypes or STs, whereas some clustering is associated with more than one ST or serotype. Seven-gene Multilocus Sequence Typing (MLST) indicated that nine sheep isolates and four cattle isolates were related to a few E. coli isolates associated with human HUS, suggesting their potential in causing severe human infections. Collectively, we described the characteristics of cattle and sheep STEC isolates from Xinjiang, China, which may be utilized in comparative studies of other geographic regions and sources of isolation and for surveillance.