Experimental inoculation of adult dairy cows with bovine coronavirus and detection of coronavirus in feces by RT-PCR

A reverse transcriptase PCR (RT-PCR) targeting a 407 bp fragment of the nuc leocapsid gene of bovine coronavirus (BCV) was developed for detection of B CV RNA in feces of experimentally inoculated cattle. The sensitivity and sp ecificity of the RT-PCR were confirmed using tissue culture-adapted BCV str ains and feces of 2 calves inoculated with BCV. Ten nonpregant, BCV seropos itive, adult dairy cows were inoculated with winter dysentery (WD) (n = 8) or calf diarrhea (CD) (n = 2) strains of BCV intranasally and orally (n = 2 ) or through a surgically-placed duodenal catheter (n = 8) with and without dexamethasone treatment or feeding ice water. The 6 cows inoculated with B CV intranasally and through a duodenal catheter (2 of 2 cows given CD BCV a nd 4 of 6 cows given WD BCV) developed mild diarrhea, and BCV was detected in diarrheal feces by RT-PCR, ELISA or immune electron microscopy. These re sults suggest that CD and WD strains of BCV can cause diarrhea in adult cow s in conjunction with host or environmental factors and that RT-PCR might b e useful to diagnose BCV infections in calves and adult cows.