102 INCLUSION OF A RECOMBINANT BOVINE TRYPSIN INTO THE IETS SANITARY PROTOCOL FOR DISINFECTION OF BOVINE EMBRYOS TO PREVENT BOVINE HERPESVIRUS 1 (BHV 1) TRANSMISSION VIA EMBRYO TRANSFER TO RECIPIENTS AND CALVES

Abstract

This study dealt with the potential for introduction of infectious agents through the use of animal-derived products. The efficacy of a recombinant bovine trypsin (RBTr) as a replacement for porcine pancreatic trypsin as a disinfectant for bovine herpesvirus-1 (BHV-1)-infected embryos was investigated according to the sanitary guidelines of the IETS. Treatment of in vivo-fertilised embryos (n = 147) contaminated with BHV-1 [10⁵ 50% tissue culture infectious dose (TCID₅₀)/mL] in the presence of RBTr (525 U mL^–1) for 120 s effectively removed the infectious virus (100%) compared with untreated and washed embryos [9/55 (16%); P < 0.05]. Transfer of in vivo-fertilised and disinfected embryos to BHV-1 seronegative recipients (n = 24) resulted in 14 pregnancies and 11 calves born free of BHV-1. In contrast, transfer of unwashed/undisinfected embryos to 4 recipients resulted in seroconversion and no pregnancies at term. The same treatment applied to in vivo-fertilised contaminated embryos removed the infectious virus from all but 1 [1/100 (99%)] compared with untreated and unwashed embryos [16/28 (57%); P < 0.05]. It was concluded that the use of RBTr can be considered as an alternative method of rendering embryos free of bovine herpesvirus and thus reduce the potential risk of disease transmission to embryo recipients and offspring.