The aims of our study were to characterize the comparative
pathogenesis (clinical disease, fecal virus shedding, viremia, and
pathology) of the wild-type US PEDV strain PC21A in nursing
piglets vs. weaned pigs; and to investigate the number of Ki67- or
LGR5-positive crypt cells in the small intestine of nursing piglets
vs. weaned pigs, inoculated with the same dose of PC21A, to
explore the basis for the age-dependent severity of PED.