Skip to main content
ARS Home » Midwest Area » Ames, Iowa » National Animal Disease Center » Ruminant Diseases and Immunology Research » Research » Publications at this Location » Publication #305978

Title: Characterization of the cytopathic BVDV strains isolated from 13 mucosal disease cases arising in a cattle herd

Author
item DARWEESH, MAHMOUD - South Dakota State University
item RAJPUT, MRIGENDRA - South Dakota State University
item BRAUN, LYLE - South Dakota State University
item Ridpath, Julia
item Neill, John
item CHASE, CHRISTOPHER - South Dakota State University

Submitted to: Virus Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/29/2014
Publication Date: 1/2/2015
Publication URL: http://handle.nal.usda.gov/10113/61335
Citation: Darweesh, M.F., Rajput, M.K., Braun, L.J., Ridpath, J.F., Neill, J.D., Chase, C.C. 2015. Characterization of the cytopathic BVDV strains isolated from 13 mucosal disease cases arising in a cattle herd. Virus Research. 195:141-147. DOI: 10.1016/j.viruses.2014.09.015.

Interpretive Summary: Bovine viral diarrhea virus (BVDV) is a common pathogen of cattle. The majority of BVDV strains are of the non-cytopathic biotype, those that do not kill infected cells. When these viruses infect a pregnant animal, the virus will cross the placenta, infect the fetus and cause a persistent infection (PI). This persistent infection is life long and the calf will spread virus wherever it goes, infecting herd mates and spreading the disease. Occasionally, a virus in a PI animal will mutate, either by incorporation of host sequences or viral genomic duplication, resulting in a cytopathic virus. The cytopathic virus does kill infected cells. This will lead to mucosal disease in the PI animal which is invariably fatal. One herd in South Dakota had 36 identified PIs. After the animals were 1 year old, some died of mucosal disease. The cytopathic viruses from these animals were isolated and the genomic changes characterized. It was found that these viruses all contained a cellular insert derived from the Jiv mRNA transcript, a common finding in BVDV cytopathic strains. However, the host sequences in these viruses were found to be of the same length and have the same borders. This indicated that there was only a single mutation event in the herd and that this cytopathic virus spread to the other animals, resulting in the fatal disease. This is the first report of following such a large number of PI animals and their persistent viruses.

Technical Abstract: Bovine viral diarrhea virus (BVDV) is a positive single stranded RNA virus belonging to the Pestivirus genus of the Flaviviridae family. BVDV has a wide host range that includes most ruminants. Noncytopathic (ncp) BVDV may establish lifelong persistent infections in calves following infection of the fetus between 40-120 days of gestation. Cytopathic (cp) BVDV strains arise from ncp strains via mutations. The most common cp mutations are insertions of RNA derived from either host or a duplication of viral sequences into the region of the genome coding for the NS2/3 protein. Superinfection of a persistently infected animal with a cp virus can give rise to mucosal disease, a condition that is invariably fatal. A herd of 136 bred first calf heifers was studied. These heifers gave birth to 36 PI animals of which 13 succumbed to mucosal disease. In this study, we characterized the ncp and cp viruses isolated from these 13 animals. All viruses belonged to the BVDV-2a genotype and were highly similar. All the cp viruses contained an insertion in the NS2/3 coding region consisting of the sequences derived from the transcript encoding a DnaJ protein named Jiv90. Comparison of the inserted DnaJ regions along with the flanking viral sequences in the insertion 3’ end of the 13 cp isolates revealed sequence identities ranging from 96%-99 % with common borders. This suggested that one animal likely developed a cp virus that then progressively spread to the other 12 animals. Interestingly, when the inserted mammalian gene replicated within viral genome, it showed conservation of the same conserved motifs between the different species, which may indicate a role for these motifs in the insertion function within the virus genome. This is the first characterization of multiple cp bovine viral diarrhea virus isolates that spread in a herd under natural conditions.