PARENT SESSION
IVF and Assisted Reproductive Technologies

EVALUATION OF VIRUS DECONTAMINATION TECHNIQUES FOR PORCINE EMBRYOS PRODUCED IN VITRO.

Bureau, Mariève¹, Dea, Serge², Sirard, Marc-André¹, ^{1 2}

ABSTRACT- Embryo transfer is a relatively simple, safe and economic technique for introduction of new genetic lines by minimizing disease transmission. Standard protocols used in commercial bovine embryo transfer recommend to wash the embryos 12 times, including 2 times with 0.25% trypsin solution. This technique does not affect bovine embryo viability, but little is known on its effectiveness on porcine embryo decontamination. Oocytes from abattoir-derived ovaries were matured and fertilized in vitro. After 7 days of culture, morulae and blastocysts were incubated with one of 5 viruses tested (bovine viral diarrhea virus (BVD), encephalo-myocarditis virus, porcine circovirus, porcine parvovirus and porcine reproductive and respiratory syndrome virus) with a multiplicity of infection of 100 TCID₅₀/embryo for 1h. Embryos were then washed with 3 different treatments: 1) 17 washes including 1 time with 0.25% trypsin for 5 min and 1 time with 0.1 mg/ml DNase1 and 20 UI/ml RNaseOne for 30 min (n=25), 2) same as 1 but without DNase and RNase treatment (n=25), 3) same as 1 but before the infection the embryos were exposed to oviductal epithelial cells vesicles (OEC) during their development (n=25). For each treatment and virus, a sample of 5 embryos was analyzed by PCR in 3 different replicates. Results indicate that every washing treatment was effective to remove BVD from the embryos. Trypsin treatment, with or without DNase and RNase treatment, was ineffective for all other viruses, except for the embryos previously co-cultured with OEC. From these results, it can be concluded that trypsin treatment is inefficient to remove viruses from embryos. The co-culture with OEC may be highly effective for porcine in vitro embryo decontamination. Supported by Fédération des Producteurs de Porcs du Québec and CORPAQ.

KEY WORDS: porcine, embryo, virus, trypsin