The efficacy of trypsin for disinfection of in vitro fertilized bovine embryos exposed to bovine herpesvirus 1

Bovine cumulus-oocyte complexes (COC) or in vitro fertilized (IVF) embryos were exposed to bovine herpesvirus 1 (BHV-1) during in vitro maturation or co-culture with uterine tubal cells, respectively. Trypsin, at a concentration of 0.25%, was applied (for approximately 90 s) to disinfect either COC or cumulus-free oocytes (CFO) 18 h after insemination, or on day 7 to embryos resulting from infected oocytes. In total, virus was not detected in 71% of 93 samples containing 233 embryos exposed to BHV-1 and trypsin treatment. BHV-1 was detected in 14% and 54% of samples containing a single embryo and five embryos, respectively. In corresponding groups of embryos exposed to BHV-1, then washed but not treated with trypsin (70 samples), 85% and 96% of samples containing one embryo and pooled embryos, respectively, were positive for the virus. There was no effect of trypsin treatment on the development of IVF-embryos. It is concluded that IVF-generated embryos have a greater tendency to carry BHV-1 after experimental exposure to the virus than IVF uterine stage embryos, and that they are more difficult to disinfect by means of the standard trypsin treatment use. (C) 1997 Elsevier Science B.V.