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Cell culture-grown putative bovine respiratory torovirus identified as a coronavirus
  1. L. A. H. M. Cornelissen, DVM1,
  2. P. A. M. van Woensel, BSc2,
  3. R. J. de Groot, PhD3,
  4. M. C. Horzinek, DVM, PhD3,
  5. N. Visser, PhD2 and
  6. H. F. Egberink, DVM, PhD3
  1. 1 Department of Large Animal Medicine and Nutrition
  2. 2 Intervet International BV, 5830 AA Boxmeer, The Netherlands
  3. 3 Virology Unit, Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, 3584 CL Utrecht, The Netherlands


A putative bovine respiratory torovirus (BRTV) was propagated in bovine fetal diploid lung and human colonic tumour cells, and fringed pleomorphic particles were detected in the culture supernatants by electron microscopy. Antisera directed against a bovine (Breda strain) and equine (Berne strain) torovirus failed to react with BRTV-infected cells in immunofluorescence assays and did not neutralise BRTV. No toroviral RNA was found in the supernatants of infected cells by means of a reverse transcriptase-polymerase chain reaction with torovirus-specific primers. On the other hand, bovine coronavirus-specific antisera and monoclonal antibodies did neutralise the cytopathic effects, and coronaviral antigen was detected in the cultures by immunofluorescence. Furthermore, bovine coronavirus RNA was detected in the supernatants of BRTV-infected cells after nucleic acid amplification. It is concluded that the cytopathic BRTV isolate is a coronavirus.

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