Author
FULTON, R - Oklahoma State University | |
D'OFFAY, J - Oklahoma State University | |
LANDIS, C - Oklahoma State University | |
MILES, D - Veterinary Research And Consulting Services Llc | |
SMITH, R - Oklahoma State University | |
SALIKI, J - Athens Diagnostics Laboratory | |
Ridpath, Julia | |
CONFER, A - Oklahoma State University | |
Neill, John | |
EBERLE, R - Oklahoma State University | |
CLEMENT, T - South Dakota State University | |
CHASE, C - South Dakota State University | |
BURGE, L - Oklahoma State University | |
PAYTON, M - Oklahoma State University |
Submitted to: Vaccine
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 4/7/2016 Publication Date: 5/31/2016 Citation: Fulton, R.W., D'Offay, J.M., Landis, C., Miles, D.G., Smith, R.A., Saliki, J.T., Ridpath, J.F., Confer, A.W., Neill, J.D., Eberle, R., Clement, T.J., Chase, C.C., Burge, L.J., Payton, M.E. 2016. Detection and characterization of viruses as field and vaccine strains in feedlot cattle with bovine respiratory disease. Vaccine. doi: 10.1016/j.vaccine.2016.04.020. Interpretive Summary: Bovine respiratory disease complex (BRDC) is a general term for respiratory disease in cattle. BRDC is a major cause of economic loss for cattle producers. BRDC results from interaction of a number of different factors including infection with pathogens and environmental issues such as stress. The nature of the interaction between these factors in causing BRDC is poorly understood. In this study samples were collected from 121 feedlot cattle suffering from BRDC. The samples were tested to determine which viruses were present and in which combination. The study also compared 3 different methods for detecting virus in these samples. One or more viruses could be identified in samples from 94 of the cattle. All three tests failed to identify virus in a portion of the samples. These results indicate that multiple viruses may be present in BRDC cases and that multiple tests need to be used to detect all the viruses that are present. Technical Abstract: This study investigated viruses in bovine respiratory disease (BRD) cases in feedlots, including bovine herpesvirus-1 (BoHV-1), bovine viral diarrhea virus (BVDV), bovine respiratory syncytial virus (BRSV), bovine coronaviruses (BoCV) and parainfluenza-3 virus (PI3V). Nasal swabs were collected from 114 cattle on initial BRD treatment after processing. Processing included delivery of modified live virus (MLV) vaccine licensed for the control of respiratory disease in cattle. In addition, 7 BRD necropsy cases were included for a total of 121 cases. Swabs and tissue homogenates were tested by genomic tests, gel based PCR (G-PCR) and real time PCR (RT-PCR) and culture using bovine monolayers and human rectal tumor monolayers. There were 87/114 (76.3%) nasal swabs positive for at least one virus by at least one test. All 7 necropsy cases were positive for at least one virus. Of 121 cases, positives included 18/121(14.9%) BoHV-1, 19/121 (15.7%) BVDV, 76/121 (62.8%) BoCV, 11/121 (9.1%) BRSV, and 8/121 (6.6%) PI3V. For the nasal swabs, G-PCR detected 44/114 (38.6%), RT-PCR (4 viruses) detected, 81/114 (71.6%), and culture detected 40/114 (35.1%). Most cases were positive for only one or two tests, but not all three tests. Necropsy cases had positives: 5/7 G-PCR, 5/7 RT-PCR, and all 7 were positive by cell culture. In some cases, G-PCR and RT-PCR were negative for BoHV-1, BVDV, and PI3V in samples positive by virus culture. PCR testing did not differentiate field from vaccines strains of BoHV-1, BVDV, and PI3V.However based on sequencing and phylogenetic analysis, field and vaccine strains of BoHV-1, BVDV, and PI3V were detected. BRSV was identified by PCR testing, but negative by virus culture. Interpretation of laboratory tests is appropriate as PCR based tests and virus isolation cannot separate field from vaccine strains. Additional testing, specifically sequencing followed by phylogenetic analysis appears appropriate for identifying vaccine strains. |