Virological and serological studies on the role of PI-3 virus, BRSV, BVDV and BHV-1 on respiratory infections of cattle. I. The detection of etiological agents by direct immunofluorescence technique.

Nasal cells extracted from nasal swabs obtained from 95 cattle with signs o f respiratory disease, out of eleven different herds, were tested for BHV-1 , PI-3 virus, BRSV and BVDV using direct immunofluorescence technique. Vira l antigen positive samples were detected in seven out of eleven herds exami ned. Of the 95 individual diseased cattle, 19 were found positive for at le ast one viral antigen. It was found that especially BHV-1 and PI-3 virus ar e important causative agents in cattle respiratory disease, both or in comb ination with other pathogenic agents. Multiple infection in virologically p ositive herds was observed in six (9.8%) of 61 animals tested. The findings reveal that single or multiple infections of selected viruses may be present in an important range in cattle and that direct immunofluore scence technique as a rapid method, based on the detection of viral antigen in nasal swab samples, is useful to establish the viral aetiology of acute bovine respiratory disease caused by these viruses, particularly in the di agnosis of mixed Viral infections.