Evaluation of ethylenediaminetetraacetic acid, tetrasodium salt dihydrate (EDTA)-Tween 20 treatment versus protease digestion of formalin-fixed tissue sections for detection of bovine respiratory syncytial virus antigen in infected ovine lung

The efficacy of protease and ethylenediaminetetraacetic acid, tetrasodium salt dihydrate (EDTA)-Tween 20 in unmasking bovine respiratory syncytial virus (BRSV) antigens in formalin-fixed lung tissue was compared using avidin-biotin immunoperoxidase procedure. Tissues were taken from experimentally infected lambs. BRSV antigen stained in both techniques. Treatment with EDTA-Tween 20 resulted in more intense staining of BRSV infected cells, more uniform cytoplasmic staining, less non-specific background, and superior cellular detail in comparison to protease digestion.     

Experimental parainfluenza type 3 infection in young lambs: clinical, microbiological, and serological response

Five, 1-week-old, colostrum-deprived lambs were inoculated transtracheally with a parainfluenza type-3 (PI-3) virus that had been isolated from a pneumonic lamb lung. A biphasic febrile response, cough, rapid breathing followed by forced expirations, listlessness, and anorexia were observed in the lambs. There were multifocal areas of consolidation in the lungs of all lambs and ulcerations in the nasal mucosa of three lambs. Serum antibody titers to PI-3 virus ranged from 2 to 16 in lambs necropsied Day 3 to Day 7 post-inoculation, respectively. Virus was isolated from nasal secretions, tracheal fluids, and lung tissues of all lambs.     

Bovine adenovirus serotype 7 infections in postweaning calves

OBJECTIVE: To detect bovine adenovirus serotype 7 (BAV-7) infections in calves by use of viral isolation and serologic testing. ANIMALS: 205 postweaning calves. PROCEDURE: 121 calves were assembled by an order buyer through auction markets in eastern Tennessee and transported to New Mexico where they were commingled with 84 healthy ranch-reared calves. Tests included viral isolation in cell culture from peripheral blood leukocytes (PBL) and detection of serum BAV-7 antibodies by use of microtitration viral neutralization. RESULTS: BAV-7 was isolated from PBL of 8 calves and seroconversion to BAV-7 was detected for 38 of 199 (19.1%) calves. Concurrent bovine viral diarrhea virus infections were detected in most calves from which BAV-7 was isolated. CONCLUSIONS AND CLINICAL RELEVANCE: Results of our study indicate that BAV-7 infections can be found in postweaning commingled calves and may develop more commonly in calves with concurrent infections with viruses such as bovine viral diarrhea virus (BVDV).     

Breed susceptibility to ovine progressive pneumonia (maedi/visna) virus

In this retrospective study of breed differences in susceptibility to disease caused by ovine progressive pneumonia (OPP) virus, 29 Border Leicester sheep were compared with 46 Columbia sheep. As judged by frequency and severity of clinical signs and lesions attributable to the infection, Border Leicester sheep were markedly more susceptible than Columbia sheep and experimentally infected sheep were slightly more susceptible than naturally infected sheep. Differences in susceptibility to infection by the virus were not determined.