ABSTRACT
This chapter reviewed the origin and the passage history of the virulent and attenuated Wa strain HRV pair that has been used in the Gn pig model of HRV infection and diarrhea for over 25 years and the comprehensive study that determined the pathogenesis and infectious doses of the virulent Wa HRV and the attenuated Wa HRV in Gn pigs. Of pigs inoculated with the virulent HRV at the dose of ~105 focus-forming units (FFU), 80–100% developed diarrhea for an average duration of four days and 100% shed virus for an average of 5.5 days. This dose of ~105 FFU HRV was used as the challenge dose for Gn pigs at 4–7 and 33–34 days of age in all the subsequent studies using this Gn pig model and it has consistently induced 80–100% of virus shedding and diarrhea in all the naïve Gn pigs when the model system is properly calibrated. The attenuated Wa HRV has been used as a prototype oral HRV vaccine in Gn pigs. Two peaks of fecal virus shedding are often observed in naïve Gn pigs infected with virulent HRV, which is likely due to rotavirus infecting the original and newly matured villus epithelial cells.
