The present invention pertains to a novel rotavirus, especially an isolated virus, which is a member of the sub-species of porcine group B rotavirus (porcine RVB), causing diarrheal disease in pigs, to DNA fragments and corresponding proteins of the said virus, to vaccines on the basis of said virus, DNA and/or protein and to antibodies reactive with said virus and/or protein and diagnostic test kits for the detection of said virus.