149 RISK ASSESSMENT OF INFECTIOUS DISEASE TRANSMISSION VIA IN VITRO EMBRYO PRODUCTION USING SOMATIC CELL NUCLEAR TRANSFER

Abstract

Somatic cell nuclear transfer (SCNT) technology is a powerful tool for preservation and propagation of superior genetics of livestock animals. Bovine oocytes derived from abattoirs are usually used in SCNT embryo production. The puncture of the zona pellucida during the nuclear transfer process has raised additional concerns about the risk of disease transmission through application of this new technology. The objective of this study was to use bovine viral diarrhea virus (BVDV) as a model to perform a comprehensive risk assessment on infectious disease transmission in the SCNT system. Thirteen batches of cumulus–oocyte complexes (COC; n = 550) were collected from several abattoirs over 6 months. Two hundred were tested for BVDV before cumulus cell removal. Cumulus cells were removed from the other 350 COC by gentle vortexing in 0.1% hyaluronidase in HEPES-M199 with Hanks’ salts. The cumulus-cell-free oocytes (CFO) were then washed 3 times with FBS-free HEPES-M199 with Hanks’ salts containing penicillin-streptomycin solution (5 μg mL^–1). Both COC and CFO were pooled in groups (5/group) and tested for presence of BVDV using sensitive real-time PCR method. Only 2.5% of the COC were BVDV positive and all of the CFO were BVDV negative. Additionally, 293 embryos were produced from 14 different cell lines using the previously described SCNT procedure (Zhou et al. 2008 Mol Reprod Dev. 75, 1281–1289). These embryos were generated using in vitro-matured oocytes collected as 23 different batches over 7 months. The embryos were cultured in vitro to blastocyst stage and then tested for BVDV. All of the 293 SCNT embryos (100%) were BVDV negative. In conclusion, under these SCNT embryo production conditions, a small portion of COC were BVDV positive. However, all CFO and SCNT embryos were BVDV negative. Therefore, the risk of disease transmission using abattoir oocytes and SCNT procedure is relatively low and can be eliminated by using a combination of cumulus cell removal and adequate oocyte washing procedures.

F. Arenivas, B. Findeisen, V. Farrar, E. Hwang helped with the SCNT embryo production for this study.