摘要:
Pathogenic infectious bovine rhinotracheitis (IBR) virus may be modified by serial passages in non-bovine tissue cultures until it becomes non-pathogenic when applied to the intranasal passages of bovines. Such application will result in the induction of high levels of interferon in nasal secretions as well as the production of local antibodies and a long lasting immunity against IBR infection by virtue of the induction of specific circulating antibodies. The invention includes the method of modifying the IBR virus, a method of preparing a vaccine therefrom and a method of immunizing bovines and promoting production of high levels of interferon in nasal secretions.