CELL CULTURE-GROWN PUTATIVE BOVINE RESPIRATORY TOROVIRUS IDENTIFIED AS A CORONAVIRUS

A putative bovine respiratory torovirus (BRTV) was propagated in bovin e fetal diploid lung and human colonic tumour cells, and fringed pleom orphic particles were detected in the culture supernatants by electron microscopy. Antisera directed against a bovine (Breda strain) and equ ine (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 rev erse transcriptase-polymerase chain reaction with torovirus-specific p rimers. On the other hand, bovine coronavirus-specific antisera and mo noclonal antibodies did neutralise the cytopathic effects, and coronav iral antigen was detected in the cultures by immunofluorescence, Furth ermore, bovine coronavirus RNA was detected in the supernatants of BRT V-infected cells after nucleic acid amplification, It is concluded tha t the cytopathic BRTV isolate is a coronavirus.