黒毛和種肥育牛に見られた牛ライノウイルス感染症

Abstract

There was an outbreak of an acute respiratory disease in cattle in Nagasaki Prefecture in March, 1987. The 45 cattle, all from different places in Nagasaki Prefecture from outsideof the prefecture, involved in the outbreak showed fever, coughing, nasal discharge, labored breathing and diarrhea five days after they were introduced and five of them died.Pasteurella haemolytica was isolated from six nasal swab specimens in seven ill cattle (85.7%). Mycoplasma SP. was isolated from two of seven specimens (28.6%). Two cytopathogenic virus strains were isolated in MDBK cell cultures from nasal swabs of cattle with markedleukopenia.The isolants were readily inactivated by acid and heating at 50°C for 30 minutes, but they resisted chloroform. The type of their nucleic acid was determined to be RNA. Immunoelectron microscopy using convalescent serum revealed picornavirus-like particles in cultured material.The isolants were neutralized with antiserum against the Sd-1 strain of bovine rhinovirus type 1.A significant rise in antibody titer was shown against the isolants in convalescent serum of the ill cattle, but not against bovine respiratory syncytiai virus, bovine adenovirus type 7, or bovine entero virus. A small rise in antibody titer against bovine herpesvirus type 1, parainfluenza virus type 3 and bovine viral diarrhea mucosal disease virus, was shown. It is considered, however, that such a sero-conversion may be due to vaccination of combined vaccine against these viral agents.Serologic survey against the isolated virus in sera collected from 195 cattle in 1987 in Nagasaki Prefecture revealed that 73. 5% of those over one year old were antibody positive, while 29. 9% of those from four to 10 months old particulaly have a tendency to show a low positive rate.