|Briggs, Robert - Bob|
Submitted to: Vaccine
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/30/2003
Publication Date: 6/20/2003
Citation: Fulton, R.W., Step, D.L., Ridpath, J.F., Saliki, J.T., Confer, A.W., Johnson, B.J., Briggs, R.E., Hawley, R.V., Burge, L.J., Payton, M.E. Response of calves persistently infected with noncytopathic bovine viral diarrhea virus (BVDV) subtype 1b after vaccination with heterologous BVDV strains in modified live virus vaccines and Mannheimia haemolytica bacterin-toxoid. Vaccine. 2003. v. 21. p. 2980-2985. Interpretive Summary: Infections with bovine viral diarrhea viruses (BVDV) are a source of major economic loss to U.S. cattle producers. Animals that are infected before birth may be born persistently infected (PI) with BVDV. These animals shed BVDV throughout their lifetimes and will infect animals they come into contact with. Detection and removal of PI animals is one of the keys to BVDV control and so there is much interest in identifying PI animals. Some producers think that PI animals cannot mount an immune response to BVDV. Others think that vaccination with modified live vaccines (MLV) will kick off a fatal disease called mucosal disease (MD) in PI animals. In this study PI animals were vaccinated with one of four modified live vaccines (MLVs). It was found that PI animals could mount an immune response if the vaccine virus was sufficiently different from the virus they were persistently infected with. None of the animals developed MD. Thus vaccination with an MLV neither allowed identification of the PI animals (as indicated by a failure to mount an immune response) or elimination of PI animals (by the development of MD). Another notable finding was that PI animals did not respond as well to a bacterial vaccine. Thus, they may be at higher risk for respiratory disease than normal animals.
Technical Abstract: Seronegative calves persistently infected (PI) with bovine viral diarrhea virus (BVDV) subtype 1b were vaccinated with each of four modified live virus (MLV) BVDV vaccines and a Mannheimia haemolytica bacterin-toxoid. Nasal swabs and peripheral blood leukocytes (PBL) were collected for virus isolation and serums were collected after vaccination and tested for BVDV1a, BVDV1b, BVDV2, bovine herpesvirus-1 (BHV-1), bovine parainfluenza-3 (PI-3), bovine respiratory syncytial virus (BRSV), M. haemolytica, and Pasteurella Multocida antibodies. None of the PI calves developed mucosal disease (MD) after MLV vaccination. None of the BVDV PI calves seroconverted to BVDV1b after MLV vaccination. Calves receiving MLV vaccines seroconverted to the respective type/subtype in the vaccine. Calves receiving an MLV vaccine noncytopathic (NCP) BVDV1 (subtype not designated) did not seroconvert to BVDV1a, BVDV1b or BVDV2. The PI calves were virus positive for BVDV subtype 1b in the PBL and nasal swabs throughout the study. Calves receiving each of three vaccines with known BVDV1a strains had BVDV1a virus positive samples after vaccination, in some but not all calves, up to day 28. The PI BVDV1b calves did not respond with increased M. Haemolytica antibodies after vaccination compared to BVDV-negative calves receiving the same M. haemolytica vaccine.