Dual enteric and respiratory tropisms of winter dysentery bovine coronavirus in calves.

Although winter dysentery (WD), which is caused by the bovine coronavirus (BCoV) is characterized by the sudden onset of diarrhea in many adult cattle in a herd, the pathogenesis of the WD-BCoV is not completely understood. In this study, colostrum-deprived calves were experimentally infected with a Korean WD-BCoV strain and examined for viremia, enteric and nasal virus shedding as well as for viral antigen expression and virus-associated lesions in the small and large intestines and the upper and lower respiratory tract from 1 to 8 days after an oral infection. The WD-BCoV-inoculated calves showed gradual villous atrophy in the small intestine and a gradual increase in the crypt depth of the large intestine. The WD-BCoV-infected animals showed epithelial damage in nasal turbinates, trachea and lungs, and interstitial pneumonia. The WD-BCoV antigen was detected in the epithelium of the small and large intestines, nasal turbinates, trachea and lungs. WD-BCoV RNA was detected in the serum from post-inoculation day 3. These results show that the WD-BCoV has dual tropism and induces pathological changes in both the digestive and respiratory tracts of calves. To our knowledge, this is the first detailed report of dual enteric and respiratory tropisms of WD-BCoV in calves. Comprehensive studies of the dual tissue pathogenesis of the BCoV might contribute to an increased understanding of similar pneumoenteric CoV infections in humans.

Detection and isolation of winter dysentery bovine coronavirus circulated in Korea during 2002-2004.

Although winter dysentery (WD) has been suspected to occur frequently in Korea, to date the exact epidemiology of WD has remained unknown. Therefore, we investigated the causative agents of WD by using electron microscopy, ELISA, RT-PCR, and nested PCR from 97 fecal samples of 32 WD-affected herds collected from 8 provinces during 2002-2004. The bovine coronavirus (BoCV) was consistently detected in all herds with WD. Of other pathogens, only coccidian oocyts were inconsistently but concurrently detected with BoCV. Ten isolates were identified as BoCV by immune electron microscope, immunofluorescent test and ELISA with antiserum to BoCV, and RT-PCR. From these results, it is concluded that WD caused by BoCV occurred in relatively high frequency and was widespread in Korea. The results provide important epidemiological data for the control and establishment of a surveillance system for WD in Korea.

Detection and isolation of coronavirus from feces of three herds of feedlot cattle during outbreaks of winter dysentery-like disease.

Clinical signs of a winter dysentery-like syndrome in 6- to 9-month-old cattle in 3 feedlots included acute onset of diarrhea with high morbidity and low mortality, respiratory tract problems that included dyspnea, coughing, and nasal discharge, and high rectal temperatures. Bovine coronavirus was detected by use of an ELISA and immune electron microscopy in fecal and nasal swab samples and by immunohistochemical analysis of intestinal sections collected from calves during necropsy. Bovine coronavirus should be considered in the differential diagnoses for diseases that cause acute onset of bloody diarrhea in feedlot cattle.

Detection of bovine coronavirus and type A rotavirus in neonatal calf diarrhea and winter dysentery of cattle in Quebec: evaluation of three diagnostic methods.

The use of direct electron microscopy, enzyme-linked immunosorbent assay, and protein A-gold immunoelectron microscopy for the identification of bovine coronavirus and type A rotavirus were examined. Two hundred and forty-nine samples from diarrheic calves and winter dysenteric cattle from seven geographic areas in Quebec were examined for the presence of viruses by direct electron microscopy of negatively stained preparations. In addition, all the samples were analyzed by enzyme-linked immunosorbent assay, and a random selection of 47 samples were also analyzed by protein A-gold immunoelectron microscopy. Thirty-nine percent of samples examined by direct electron microscopy contained viral particles; bovine coronavirus and type A rotavirus were the most common viruses involved. Overall agreement between any two of the methods used compared favorably with results obtained by others using similar methods. The presence of coronavirus and rotavirus in fecal samples obtained from neonatal calves and the presence of coronavirus in samples from winter dysenteric adult cattle suggested their etiological roles in the respective diseases. Furthermore, results from protein A-gold immunoelectron microscopy of coronavirus-like particles implied that a different coronavirus or some other viruses might be involved in these diseases. Finally, the efficiency of direct electron microscopy, enzyme-linked immunosorbent assay and protein A-gold immunoelectron microscopy as diagnostic tools is discussed.