 Perhaps the porcine parainfluenza 1 was responsible for pigs disease in Japan in 1953–1956.However, the antigenic cross-reactivity among these two representatives within the genus Respirovirus may explain why SeV antibodies were found in sick pigs, and why it was thought that SeV was the etiological causative agent of pigs disease.Human parainfluenza virus type 1, also shares common antigenic determinants with SeV and triggers the generation of cross-reactive neutralizing antibodies.