Bovine Respiratory Syncytial Virus, Bovine Coronavirus, and Bovine Viral Diarrhea Virus Diagnosis by PCR Testing of Nasal Swabs

Comparison with Cell Culture Procedures

Abstract

Diagnosis of viral infections has traditionally used viral isolation in cell culture and serologic testing (antibody levels) to detect active infection (rising antibody levels). These procedures require considerable time for the results, especially cell culture isolation (days to weeks for multiple passages). Serology requires the host response post infection (3-4 weeks for acute to convalescent samples), plus the antibody test performance. Use of cell culture systems for viral diagnostics is useful for selected viruses, yet some viruses may not be readily identified in cell culture or may require unique cell cultures not normally maintained in diagnostic laboratories. Also, some viruses may be quite labile and have reduced chance of recovery due to time and conditions of shipment. There are a limited number of rapid antigen detection systems available for diagnoses of viruses causing BRD. An antigen capture ELISA test for BVDV, used primarily as a test for persistently infected (Pl) BVDV cattle using fresh ear notches, is a newer and more rapid test.

Molecular diagnostic testing, such as reverse transcriptase polymerase chain reaction (RT-PCR), offers a rapid means and greater sensitivity than the traditional tests like cell culture assay and serology. The nucleotide sequences for primer selection for the RT-PCR are available. The purpose of this study was two-fold: 1) implement RT-PCR tests for BRSV, BCV and BVDV using nasal swab samples from cattle; and 2) compare the RT-PCR results for BRSV, BCV and BVDV with cell culture assay results.