IN-VITRO FERTILIZATION AND IN-VITRO CULTURE OF BOVINE EMBRYOS IN THE PRESENCE OF NONCYTOPATHIC BOVINE VIRAL DIARRHEA VIRUS

In vitro embryo production has been used extensively in research and i s now offered as a commercial service, yet the hazards of introducing specific infectious agents into in vitro embryo production systems hav e not been completely defined. The introduction of noncytopathic bovin e viral diarrhea virus (BVDV) is a special concern. One objective of t his study was to determine if noncytopathic BVDV-infected uterine tuba l cells in NF and NC systems affected the rate of cleavage and develop ment. An additional objective was to determine if either degenerated o va or embryos produced in the presence of the infected cells had virus associated with them after washing. Follicular oocytes (n=645) collec ted from slaughterhouse ovaries were matured and fertilized in vitro, and presumptive zygotes were cultured for 7 d. Primary cultures of ute rine tubal cells for use during IVF and IVC were divided into 2 groups . One-half of the cultures was infected with noncytopathic BVDV while the other half was not exposed to the virus. Approximately equal group s of mature oocytes were inseminated, and the presumptive zygotes were cultured with infected or noninfected uterine tubal cells. After 7 d in NC, zona pellucida-intact (ZP-I) morulae and blastocysts and degene rated ova were washed and assayed for the presence of infectious virus . Infections of uterine tubal cells were not apparent and did not redu ce rates of cleavage and development (P > 0.05; Chi-square test for he terogeneity). After washing, BVDV was isolated at a significantly high er rate from groups of virus-exposed degenerated ova (79%) than from i ndividual virus-exposed morulae and blastocysts (37%; P = 0.0002; Mant el-Haenszel summary, Chi-square). (C) 1997 by Elsevier Science Inc.