Cell-mediated and humoral immunity in bulls infected with IBR/IPV virus (BHV 1).

Time-related changes in specific cell-mediated immunity (CMI) and in humoral immunity were monitored in 20 bulls, aging 12 to 16 months, in four groups, each consisting of 5 animals. Group I was experimentally and group III-naturally infected with BHV 1 virus, groups II and IV serving as control animals. Tests for CMI included delayed type hypersensitivity (DTH), leukocyte migration inhibitory factor (LMIF) and granulocyte migration inhibitor factor (GMIF-LIF-buffy coat leukocyte migration inhibitory factor) in the presence of BHV I antigen while humoral immunity was tested by serum induced neutralization of the virus (SN) and by estimation of serum IgG, IgG1, IgG2, IgM and IgA levels. Immunologic, virologic and clinical studies were performed two days before infection and 17 timed within 91 days after the infection in bulls of group I and II and 7 times within 42 days after developing the disease in bulls of groups III and IV. The results showed that positive CMI reactions appeared 3 to 4 weeks earlier than positive antibody titers in SN test. The antibodies belonged most probably to IgG1 and IgG2 subclasses.