Antigenic variation among bovine enteric coronaviruses (BECV) and bovine respiratory coronaviruses (BRCV) detected using monoclonal antibodies

Bovine coronavirus (BCV) causes neonatal calf diarrhea (CD) and is associat ed with winter dysentery (WD) in adult dairy cattle. It can also be isolate d from the respiratory tracts of cattle entering feedlots. Monoclonal antib odies (MAbs) specific for the hemagglutinin esterase (HE) and spike (S) sur face proteins of 2 bovine enteric coronavirus (BECV) strains and two bovine respiratory coronavirus (BRCV) strains were tested against 6 BECV strains and 6 recently isolated BRCV strains, in order to characterize the antigeni city of BCV strains with varied tissue tropisms. All MAbs had high immunofl uorescence (LF) titers against BECV and BRCV strains, indicative of conserv ed cross-reactive epitopes. In hemagglutination inhibition (HI) tests, the S-MAbs were more broadly reactive than HE-MAbs. The BRCV and CD MAbs were m ore broadly reactive in HI than the WD MAbs. The HA activity of the Mebus v accine CD strain was not inhibited by any of the MAbs tested. The HI activi ty of BRCV strain R6 was unique among the 6 BRCV isolates. In virus neutral ization assays, MAbs to the BRCV strain R4 neutralized all 6 BECV strains t ested. Antigenic variation exists among both BECV and BRCV strains, but it cannot be attributed soley to the clinical origin of the strain.