Sensitivity comparison for detection of respiratory bovine coronaviruses in nasal samples from feedlot cattle by ELISA and isolation with the G clone of HRT-18 cells.

A monoclonal antibody-based capture enzyme-linked immunosorbent assay (ELISA) was developed to detect respiratory bovine coronavirus (RBCV) antigens in nasal swabs collected from cattle showing signs of respiratory tract disease following shipping. These samples had been previously tested for RBCV by inoculation of G clone cultures of human rectal tumor cells (HRT-18G) and for bovine herpes virus 1, parainfluenza virus 3, bovine adenovirus, bovine respiratory syncytial virus, and bovine viral diarrhea virus on other specifically permissive cell cultures. RBCV has not previously been recognized as an important etiological factor in the bovine respiratory disease complex of feedlot cattle. Thirty of 100 samples tested positive for RBCV antigen by capture ELISA in contrast to 38 of 100 samples that yielded RBCV isolates in G clone cells. Samples yielding other bovine respiratory viruses in the absence of RBCV were negative in the capture ELISA, which was based on the use of a single monoclonal antibody that recognizes one RBCV epitope on the S glycoprotein with the broadest reactivity with different strains of RBCV tested. Some RBCV strains may not be detected by this ELISA, which may account for the higher percentage of RBCV-infected cattle detected by RBCV isolation. However, the ELISA was simple to perform, sensitive, and specific and was more rapid than virus isolation. This assay will be useful for processing large numbers of field samples in future epidemiologic and diagnostic studies of RBCV infections of cattle.