Noncytopathogenic bovine viral diarrhea virus (BVDV) reduces cleavage but increases blastocyst yield of in vitro produced embryos

The growing application of in vitro embryo production systems that utilize slaughterhouse tissues of animals of unknown health status conveys the risk of disease transmission. One pathogen of concern in this regard is bovine viral diarrhea virus (BVDV), and the objective of this study was to investigate the effect of BVDV on in vitro embryonic development. A bovine in vitro embryo production system was experimentally infected with BVDV at 2 stages: prior to in vitro maturation by incubating cumulus-oocyte complexes (COC) with virus (strain Pe515; titer 10 6.2 tissue culture infective dose (TCID) 50/mL) or vehicle for 2 h, and then during in vitro culture by the use of BVDV infected granulosa cells. Exposure to BVDV throughout in vitro production reduced cleavage rates (P=0.01) but increased (P=0.05) the number of embryos that reached the 8-cell stage when expressed as a percentage of cleaved oocytes. Blastocyst yield was increased by the presence of virus when expressed as a proportion of oocytes (P=0.0034) or of those cleaved (P