Uterine tubal cells remain uninfected after culture with in vitro-producedembryos exposed to bovine viral diarrhea virus

Bovine viral diarrhea virus (BVDV) has been isolated from washed and sonica ted, in vitro-produced embryos, but the infectivity of BVDV associated with intact, developing, embryos has not been demonstrated. The objective of th is study was to determine if a dose of BVDV infective for coculture cells w as associated with individual, developing embryos, following artificial exp osure to the virus and washing. In 5 replicates, zona pellucida-intact, in vitro-produced embryos; were assigned to a negative control embryo group, o r were incubated in 10(5)-10(6) cell culture infective doses (50%, CCID50) per milliliter of a type I, noncytopathic (strain SD-1) BVDV for 2h. Unexpo sed negative control embryos and exposed positive control embryos were wash ed, sonicated and assayed for BVDV using virus isolation with immunoperoxid ase monolayer assay. Immediately or following cryopreservation, remaining v irally-exposed, washed embryos were co-cultured individually with BVDV-nega tive cultures of bovine uterine tubal cells in a medium free of BVDV-neutra lizing activity. After two days in culture, uterine tubal cells and embryos (including the zona pellucida) were separated and washed. The culture medi um, uterine tubal cells and embryos were then assayed for BVDV. Bovine vira l diarrhea virus was not isolated from any negative control embryo group, b ut was isolated from all positive control embryo groups. Although all uteri ne tubal cell populations were confirmed to be susceptible to BVDV, virus w as never isolated from uterine tubal cells or embryos from post-exposure cu lture. In conclusion, although BVDV remains associated with washed in vitro -produced embryos, the virus associated with unsonicated embryos was not in fective for uterine tubal cells in vitro. (C) 1999 Elsevier Science B.V. Al l rights reserved.