Analysis of the excretion dynamics and genotypic characteristics of rotavirus A during the lives of pigs raised on farms for meat production.

To determine the excretion dynamics and genotypic characteristics of rotavirus A (RVA), a longitudinal observational study was performed in 10 pigs from 3 litters at a farrow-to-finish farm. A total of 400 fecal samples were directly collected from the rectums of individual pigs (aged 7 to 217 days) at 3- to 14-day intervals. Seventy-one samples (17.5%) were positive for RVA by reverse transcription-PCR designed to detect the VP7 and VP4 genes. At least 13 combinations of 5 G (G2, G4, G5, G9, and G11) and 6 P (P[6], P[7], P[13], P[23], P[27], and P[34]) genotypes were identified by direct sequencing of the PCR products. We were able to detect RVA VP7 sequences from each pig 4 to 6 times with intervals of 7 to 52 days (from 7 to 119 days of age). Each pig harbored RVAs with at least 3 to 6 different combinations of G and P genotypes, while repeated excretions of RVAs carrying the same combinations of G and P genotypes were also observed. Virus shedding and changes in G and P genotypes appeared to be associated with movement of the pigs into weaning, growing, and finishing barns. These results indicated that, over their lifetimes, pigs raised for meat frequently and intermittently excrete genetically diverse RVAs.