engleski

Detection and isolation of a bovine coronavirus in neonatal calf diarrhea in Croatia

Coronaviruses and rotaviruses are the most common viruses involved in neonatal calf diarrhea. The symptoms of the disease appeared on two farms in central part of Croatia. Fecal samples from diarrheic calves were collected from six calves from farm A and ten calves from farm B. Viral RNA was extracted from fecal suspensions and reverse transcribed to cDNA. Oligonucleotide primers were designed by aligning nucleotide sequences of a nucleocapsid gene of four bovine coronaviruses and VP6 gene of three bovine type A rotaviruses published in GenBank, respectively. Agarose gel electrophoresis of PCR amplified products showed fragments of expected size in positive control sample (commercial live vaccine which contains both viruses) as well as in tested samples. A 406-bp PCR product of bovine coronavirus was present in three tested samples and 294-bp product of bovine type A rotavirus in two samples, all originated from farm A. On farm B, bovine coronavirus was detected in eight samples and rotavirus only in one sample. Mixed infection was present in one sample on both farms. Suspension from each sample was also inoculated into bovine embryo kidney cells (BEK). Cytopathic effect typical for coronaviruses was observed after ten passages when RNA extraction and bovine coronavirus specific RT-PCR was performed again and confirmed the isolation of the virus. Propagation and isolation of bovine type A rotavirus failed. In this study, we detected and isolated for the first time a bovine coronavirus involved in calf neonatal diarrhea in Croatia.

bovine coronavirus; calf diarrhea

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