TRANSMISSION OF AUJESZKYS-DISEASE (PSEUDORABIES) VIRUS IS BLOCKED BY TRYPSIN TREATMENT OF TRANSFERRED EMBRYOS

Four seronegative sows from a farm free of Aujeszky's disease (AD) wer e artificially inseminated and concurrently infected intranasally and intrauterinally with 105 dose of a virulent strain of Aujeszky's disea se virus (ADV). The embryos were recovered surgically 5 d later. The v irus could be re-isolated from nasal and vaginal swabs and from differ ent parts of the genital organs (ovary, oviduct, uterus and cervix) of all infected sows. In 2 of the infected sows ADV was also found in th e flushing medium used for embryo recovery. The results of virus isola tion were confirmed by dot-blot hybridization and histological finding s. Embryos with an intact zona pellucida (ZP) collected from the 4 don ors were treated twice with 0.25% trypsin solution for 1 min each time prior to transfer into a seronegative sow. The recipient sow and her offspring remained ADV-seronegative on Day 28 after farrowing, indicat ing that the transmission of ADV had been blocked during the embryo tr ansfer. Untreated control embryos transferred into AD-free recipients caused seroconversion based on the serum neutralization test carried o ut 40 d later.