Experimental transmission of bovine viral diseases by insemination with contaminated semen or during embryo transfer
Schlafer, D.H.; Gillespie, J.H.; Foote, R.H.; Quick, S.; Pennow, N.N.; Dougherty, E.P.; Schiff, E.I.; Allen, S.E.; Powers, P.A.; Hall, C.E.
Deutsche Tierärztliche Wochenschrift 97(2): 68-72
1990
ISSN/ISBN: 0341-6593 PMID: 2155769 Document Number: 348853
Three experimental approaches were used to study transmission of blue tongue (BT), infectious bovine rhinotracheitis (IBR) and bovine virus diarrhoea (BVD) viruses. These were insemination with contaminated semen, experimental infection of embryo donor cows, or transfer of embryos experimentally exposed to virus in vitro to normal recipients. Parameters assessed included number and quality of embryos produced, virus detection (isolation and electron microscopy), serology and histopathology. All superovulated susceptible cows inseminated with semen containing blue tongue virus (BTV) (n = 2) or infectious bovine rhinotracheitis virus (IBRV) (n = 2) became infected. One cow inseminated with semen containing BTV produced seven virus-free seven-day-old embryos; the second cow failed to produce any embryos. One of two cows inseminated with semen containing IBRV produced two underdeveloped, virus-free embryos while no embryos were produced by the second cow. One of two cows inseminated with semen containing bovine viral diarrhoea virus (BVDV) became infected. Two poorly developed, virus-free seven-day-old embryos were recovered from one of these cows. Superovulated susceptible cows inoculated either intramuscularly with BTV (n = 3) or intranasally with IBR virus (n = 2) became infected. Virus was isolated from some tissues of two BTV-infected cows, neither of which produced embryos. A third BTV-infected cow produced two virus-free embryos collected at necropsy five days after inoculation. One of two cows experimentally infected with IBR virus, produced three embryos but virus was not detected either by electron microscopy (1 embryo) or in cell culture by cytopathic alterations (1 embryo). Virus was, however, detected in the embryo by using an IBR nucleic acid probe in material taken from a cell culture exposed to the embryo, emphasizing the importance of using highly specific and sensitive probes. Six seven-day-old embryos that were exposed in vitro to BTV (n = 3) or IBRV (n = 3 cows) for 18-24 h and subsequently washed a maximum of three times were transferred to synchronized recipients. Blue Tongue virus was isolated from the blood and vaginal swab samples taken at day seven from one heifer but not from two other. None of the three heifers became pregnant, but all three developed specific serum-neutralizing antibody titers. IBRV was isolated from the reproductive tissues and blood or spleen of two cows and neither cow produced embryos. No virus was recovered by cell culture from selected tissues of the third cow or from a liver of two viable 59-d-old fetuses recovered at necropsy. These latter findings underscore the critical IETS recommendations for 10 washes as currently recommended to prevent possible transmission of disease to susceptible recipients.