Immunodiffusion assay as a method of bovine leucosis post-mortem diagnosis

Abstract

New method of post-mortem diagnosis of bovine leukosis is proposed and it involves use of agar gel immunodiffusion assay. The proposed method allows for the detection of antibodies against bovine leukemia virus (BLV) antigen located in the muscle and tissue fluids (plasma and lymph) of meat and offal. Post-mortem sampling was performed by dragging sterile cotton swabs across different parts of carcass and organs of both animals known to be seronegative and animals not tested alive. The collected samples and accompanied documents were submitted to the laboratory. 0.5–0.7 ml of isotonic solution (0.85% sodium chloride solution) were added to the tube with the swabs and the tube was left for 3–5 hours at 18–26 °C until homogenous substance formation. The tube was occasionally shaken so that BLV antibodies moved to the normal saline solution for further immunodiffusion assay. The assay results were visually recorded by detection of precipitation lines. Testing of 175 samples collected from animals not serologically tested for bovine leukosis before slaughter demonstrated five positive results (2.9%). Immunodiffusion assay of the tissue (lymphatic) fluid swabs collected from 148 animals, declared BLV seronegative alive in the veterinary certificates, demonstrated negative results. Therefore, along with autopsy, histological, molecular and genetic methods the immunodiffusion assay can be one of the tools for post-mortem diagnosis of bovine leukosis.