Kontrola hrane za životinje klasičnom mikroskopijom - primena metode u prevenciji bovine spongiformne encefalopatije

Abstract

Bovine spongiform encephalopathy (BSE) or "mad cow disease” is a progressive, fatal, neurodegenerative disease of cattle. It belongs to the transmissible spongiform encephalopathies (TSE), also known as prion diseases. The causative agent is an abnormal, pathological prion protein that accumulates in brain tissue, leading to characteristic histopathological changes. The disease was discovered in the 1980s, and as a completely new and unknown disease of cows with pronounced neurological signs, was not only a challenge, but also an obligation of the scientific and professional public to determine the etiological agent and try to stop the further spread of the disease. Epizootiological studies have established that the disease is transmitted through contaminated feed, primarily meat and bone meal (MBM) of ruminants containing infectious prion protein. The European Commission has issued several regulations prohibiting the use of these nutrients in the ruminant diet, thereby preventing the "recycling" of BSE agents in the ruminant population. The officially accepted methods by the European Union for detection of presence of animal proteins in feed are classical light microscopy and PCR, as one of the control measures in prevention and control of disease. The principle of the method is to detect the components of animal origin in a feed sample that has been properly prepared. The identification of the components of animal origin is carried out in two fractions of the sample. Bone, muscle fibers, hair, feathers, horns, gills and other parts of animal tissues can be observed on the basis of typical, microscopically characteristics. Microscopy can easily discern the difference between MBM obtained from terrestrial animals and fishmeal, and the main disadvantage of the method is the inability to determine the species of terrestrial animal from which the food components originate. Animal proteins could be detected in very small amounts (<0.1%) by this method making it very sensitive, and the advantage of the method is certainly due to its speed of execution, and does not require expensive equipment and reagents. In our country, this method is successfully implemented in two accredited laboratories (“Scientific Veterinary Institute of Serbia” and Scientific Veterinary Institute “Novi Sad”), and the success is reflected in cooperation with EU reference laboratories and comparative inter-laboratory testing.