Congenital myoclonus in swine: is the bovine viral diarrhea virus an etiologic agent?

Abstract

Swine, under natural conditions, can become infected by Bovine Viral Diarrhea Virus (BVDV), a ruminant pestivirus that leads to reproductive and economic losses. In pigs, infection with BVDV is not well known, but studies in cattle suggest that the virus could lead to hypomyelination and cerebellar hypoplasia, causing congenital tremors in newborns. This study aims to promote infection of sows with BVDV-2 and evaluate the action of the agent on the central nervous system of the fetus. Thus, this work will be conducted in two stages, as the first simulating field conditions, and the second outlining experimental conditions by intrauterine fetal inoculation. For the first study, will be selected four groups compound by two sows each, as three groups will receive a viral suspension of BVDV-2 orally at different gestational stages, and a group will be the control. For the second study, will be held fetal intrauterine inoculation by surgical procedure in two sows at 60 days of gestation. Blood samples will be taken from all piglets for serology (VN) and RT-PCR, and half of newborns will be euthanized at birth, and from these will be collected cerebral cortex fragments, cerebellum and spinal cord to histopathology and RT-PCR, checking if there is the presence of BVDV-2 in these tissues. The same will be done with piglets of the second study, in order to clarify the role of the immune barrier and placenta in the course of infection. Piglets which remain alive will be recreated and clinically evaluated every day, and will be collected blood samples every 3 days during 35 days, which will be submitted to serology and RT-PCR. At the end of the 35 days, the pigs will be euthanized and central nervous system samples will be collected and evaluated. (AU)