Many astrovirus (AstV) species are associated with enteric disease. In this study, the prevalence rates of porcine AstV types 1–5 (PAstV1–PAstV5) in the U.S. pig population were investigated using fecal samples from 509 pigs. Specifically, two multiplex differential PCR assays capable of detection and differentiation of all five known PAstV were developed. Among the 509 pigs tested, 488 (95.9 %) came from farms with a history of diarrhea. All of the five known PAstV types were found to circulate in pigs in the U.S., and co-infection of a single pig with two or more PAstV types was frequently observed. A high overall prevalence of 64.0 % (326/509) of PAstV RNA-positive samples was detected, with 97.2 % (317/326) of the PAstV RNA-positive pigs infected with PAstV4. The first complete genome of a PAstV3 isolate was obtained and showed identities of 50.5–55.3 % with mink AstV and the novel human AstVs compared with 38.4–42.7 % with other PAstV types. Further extensive attempts to grow PAstV in vitro were unsuccessful. In vivo inoculation of pigs with PAstV RNA positive material resulted in short duration of PAstV shedding of low magnitude (less than a week) followed by seroconversion. Lesions were not detected in any of the pigs.

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