Experimental transmission of bovine viral diseases by insemination with contaminated semen or during embryo transfer

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 sesceptible 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).(ABSTRACT TRUNCATED AT 400 WORDS)

In vitro protective effect of bacteria-derived bovine alpha interferon I1 against selected bovine viruses

We used bacteria-derived bovine alpha-interferon I1 (Bo IFN-alpha I1) to study its antiviral effect in a bovine turbinate cell line on bovine diarrhea virus, infectious bovine rhinotracheitis virus, parainfluenza 3 virus, and pseudorabies virus. We based our study upon replicate tests for each strain by using a block titration system with various concentrations of Bo IFN-alpha I1 against various concentrations of virus. The data were compiled in two-axis tables (replicate X concentration) and were statistically analyzed by the Spearman-Kärber method. An increase in the concentration of Bo IFN-alpha I1 enhanced its protective effect against every test virus strain. Bo IFN-alpha I1 had a marked in vitro effect on the bovine diarrhea viral strains. It demonstrated less protection against the pseudorabies and parainfluenza 3 viruses. Its effectiveness against the two infectious bovine rhinotracheitis viral strains was lesser and of a low order.

Detection of rotavirus in horses with and without diarrhea by electron microscopy and Rotazyme test

A total of 142 equine fecal samples (93 field fecal and 49 experimental fecal specimens) were examined for rotavirus using direct electron microscopy (EM) and the Rotazyme test. Eighty-six stool specimens were diarrhea samples. The Rotazyme test sensitivity and accuracy as compared to EM was determined by the visual (color reaction) and spectrophotometric methods. The overall agreement was 94.8% and 92.3% between EM and Rotazyme visual and spectrophotometric methods, respectively when suspect reactions (1 + color reaction or net absorbance between 0.05 and 0.1) were not included. The Rotazyme test is a quick, simple, and accurate diagnostic test for detection of rotavirus in equine fecal samples. It could be used by the equine practitioner with a minimum of laboratory facilities and by diagnostic and research laboratories.