Pestiviruses cause persistent infection in ruminants via transplacental infection and immunotolerance, with successful control programs relying on the removal of persistently infected animals.
Persistent infection by ruminant pestiviruses relies on virally encoded interferon antagonists, and removal of persistently infected animals is effective for viral control.
Pestiviruses cause economically important diseases among domestic ruminants and pigs, but they may also infect a wide spectrum of wild species of even-toed ungulates (Artiodactyla). Bovine viral diarrhea virus (BVDV) and Border disease virus of sheep infect their hosts either transiently or persistently. Cellular and humoral immunotolerance to the infecting strain is a unique feature of persistent infection (PI) by ruminant pestiviruses. Persistence, caused by transplacental infection early in fetal development, depends on virally encoded interferon antagonists that inactivate the host's innate immune response to the virus without globally interfering with its function against other viruses. At epidemiological equilibrium, approximately 1-2% of animals are PI. Successful BVDV control programs show that removal of PI animals results in viral extinction in the host population. The nucleotide sequences of ruminant pestiviruses change little during persistent infection. Nevertheless, they display large heterogeneity, pointing to a long history of virus-host coevolution in which avirulent strains are more successful.
Schweizer et al. (Fri,) conducted a review in Pestivirus infection. Pestiviruses cause persistent infection in ruminants via transplacental infection and immunotolerance, with successful control programs relying on the removal of persistently infected animals.
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