Serotypic differentiation of rotaviruses in field samples from diarrheic pigs by using nucleic acid probes specific for porcine VP4 and human and porcine VP7 genes.

Of 216 fecal and intestinal samples collected from nursing or weaned diarrheic pigs in the United States and Canada, 57 were identified as group A rotavirus positive by RNA electrophoresis and silver staining. Fifty-seven and 52 rotavirus-positive samples were analyzed by hybridization with Gottfried and OSU PCR-derived gene 9 and 4 probes, respectively. Only 17 samples were identified with either homologous VP4 (P)- or VP7 (G)-coding genes or both. One rotavirus identified as G4 and P7 was similar to the previously characterized interserotype rotavirus, SB-1A. Additional hybridization analyses were performed with PCR-derived probes prepared from gene 9 cDNA of the human rotaviruses Wa (G1), DS-1 (G2), and P (G3) and of the porcine rotavirus YM (G11). Eleven of 52 samples collected and analyzed from swine in Ohio, California, and Nebraska were identified as G11. No samples with G1-, G2-, or G3-type specificities were detected among the 25 of 57 rotavirus-positive samples analyzed with human rotavirus-derived probes. Further investigations with a PCR-derived gene 4 probe prepared from porcine rotavirus YM revealed hybridization specificities similar to those of the OSU gene 4 probe.