Submitted to: Virology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 27, 1995
Publication Date: N/A
Interpretive Summary: Bovine viral diarrhea viruses (BVDV) may exist as one of two types. One type, cytopathic, kills cells quickly in culture and one type, noncytopathic, does not. Researchers think that a noncytopathic type may switch to a cytopathic type by incorporating extra genetic material. These two types of BVDV work together to cause a highly fatal disease called mucosal disease (MD). To protect against BVDV infection in their herds, some producers have used a vaccine that contains a live cytopathic BVD virus. The research, presented in this paper, shows that this vaccine may indirectly cause death. The data suggests that the vaccine virus may trigger MD by causing a noncytopathic BVDV to switch into a cytopathic BVDV.
Technical Abstract: Bovine viral diarrhea viruses (BVDV) are segregated into two genotypes, BVDV 1 and BVDV 2. Viruses within both genotypes may exist as one of two biotypes, cytopathic or noncytopathic. A highly fatal form of BVDV termed mucosal disease (MD) occurs when an animal persistently infected with noncytopathic BVDV become superinfected with cytopathic BVDV. In this study, we characterized a noncytopathic (BVDV2-125nc)/cytopathic (BVDV2- 125c) viral pair isolated from an animal that died of MD three months after vaccination with modified-live BVDV1-NADL. In comparison to BVDV2-125nc, BVDV2-125c contained a 366-nucleotide insertion. The insertion was in the correct reading frame for the large open reading frame of the BVDV genome and occurred in the portion of the genome that codes for the p125 viral polypeptide. There was a 99% identity between the inserted sequences found in BVDV2-125c and sequences from the vaccine virus, BVDV1-NADL. These data asuggest that MD was induced after a recombination between noncytopathic BVDV2-125nc and cytopathic vaccine virus, BVDV1-NADL, created the cytopathic virus BVDV2-125c.