Degree Type


Date of Award


Degree Name

Doctor of Philosophy


Veterinary Pathology

First Advisor

John J. Andrews

Second Advisor

John P. Kluge

Third Advisor

Prem S. Paul


The pathogenesis of a new serotype of porcine group A rotavirus (ISU64) which is closely related to serotype 9 of human group A rotaviruses was studied in neonatal gnotobiotic (NG) and weaned conventional (WC) pigs by light, immunofluorescent, scanning electron and transmission electron microscopy;Lesions and disease in NG pigs were severe and typical of those which have been described for serotypes 4 and 5 porcine group A rotavirus in NG pigs. Virus challenged NG pigs developed severe diarrhea by 16-18 hours post inoculation (PI) and half of the pigs became depressed and inappetent. Gross examination demonstrated dilatation of the lumen of the small and large intestines with abundant watery flocculent contents. Virus replication and lesions were predominantly in the distal 2/3 of the small intestine. Maximal immunofluorescence occurred in villous enterocytes by 18-24 hours PI and villous atrophy reached maximal severity in the ileum by 18 hours PI and in the midjejunum by 24 hours PI. Villi in the midjejunum through the ileum were 1/10 to 1/5 the length of those in control pigs;A model of rotavirus challenge in susceptible WC pigs was developed. No differences were noted between control and virus challenged WC pigs in attitude, appetite or fecal consistency. Gross examination of virus challenged WC pigs revealed dilatation of the small intestine lumen with increased amounts of watery contents and a more fluid consistency of ceacal and proximal colonic contents when compared to those in control pigs. Virus replication and lesions were predominantly in the proximal 2/3 of the small intestine. Maximal immunofluorescence in villous enterocytes and maximal villous atrophy was present by 3 days PI. The degree of villous atrophy varied between pigs and was most consistent and severe in the midjejunum where villi were 1/3 normal length.



Digital Repository @ Iowa State University,

Copyright Owner

Gregory Wayne Stevenson



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126 pages