Submitted to: Research Workers in Animal Diseases Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 11/8/1999
Publication Date: N/A
Technical Abstract: Total and isotype immunoglobulins (Ig) were assessed by an indirect ELISA, and the antigenicity of the respiratory bovine coronavirus (RBCV) structural proteins was defined by immunoblot tracing among 105 cattle involved in a shipping fever epizootic. Cattle nasally shedding RBCV at the beginning had primary immune responses with antibodies for hemagglutinin-esterase (HE) and spike (S) proteins. Nasal RBCV shedding o these cattle decreased with the appearance of HE- and S-specific antibodies. The ratio of IgG1 to IgG2 was higher for clinically normal cattle than for sick cattle. Lung tissues from 9 of the 10 fatal cases had high loads of RBCV, but cattle only had initial IgM responses to RBCV. Protective immunity associated with antibodies against HE, S, and nucleocapsid (N) proteins and with IgG2 as the major isotype was detected in cattle that remained clinically normal and RBCV-negative. Clinically sick and RBCV-negative calves mounted immune reactions against HE, S, and proteins without any predominant antibody isotype. The HE and S glycoproteins were recognized earliest by the bovine immune system; while N protein induced antibodies during the recovery phases. The membrane (M) glycoprotein was the least immunogenic.