Relevance. Currently, BVD is widespread in almost all countries of the world with intensive livestock farming. The special relevance of the problem lies in the large economic damage that consists of a decrease in milk yield during the disease, the death of young animals from serous pneumonia, the loss of live weight gain in young animals, the loss of productivity and reproduction of animals and, as a result, abortions and stillbirths, the birth of non-viable calves, as well as preventive, quarantine and liquidation measures. An important link in preventing the spread of viral diarrhea in cattle remains the rapid conduct of laboratory research. One of the most technologically advanced diagnostic methods is real-time polymerase chain reaction.Methods. The diagnostic significance of the VetMAX BVDV Screening (Thermo Fisher) RT-PCR test system was assessed by sensitivity, specificity, and precision in conditions of repeatability and reproducibility. To determine repeatability, 5 samples of PT-80 cell culture infected with the reference strain "Oregon 24" and 7 samples of PT-80 cell culture infected with Ressa isolate were studied in tenfold dilutions from 10-1 to 10-7, by one operator in three parallel studies on the same equipment. To determine reproducibility and sensitivity, 5 samples of PT-80 cell culture infected with the reference strain "Oregon 24" and 7 samples of PT-80 cell culture infected with «Ressa» isolate were studied in ten-fold dilutions from 10-1 to 10-7 , by three operators on different days on the same equipment.To determine the specificity, studies were conducted on 3 samples that did not contain the virus of viral diarrhea — bovine adenovirus type 1 strain Bovina — 10, rhinotracheitis virus of cattle strain "Orenburg" and parainfluenza virus 3 strain ZKSM.Results. After mathematical processing of the results of PCR formulation for the assessment of reproducibility, the following results were obtained: the coefficient of variation (CV) for the VetMAX BVDV Screening (Thermo Fisher) test system was from 1.0–4.0 %; the Coefficient of variation (CV) for the assessment of repeatability was 1–3 %. The specificity of the test systems VetMAX BVDV Screening (Thermo Fisher) was 100%. The VetMAX BVDV Screening (Thermo Fisher) test system is sensitive to detecting the genome of the bovine viral diarrhea virus. So when setting up PCR samples of the Ressa isolate in the 10-7 dilution, the CT values were determined at 38.18–39.24 cycles, and the reference VD virus "Oregon 24" in the 10–5 dilution at 37.85–39.45 amplification cycles.
The most common type of falsification of animal products is the substitution of raw materials of more valuable types with less valuable ones, including poultry meat. This paper presents the results of identification of undeclared chicken DNA in meat products using real-time polymerase chain reaction to detect falsification of products sold in Moscow and the Moscow region. As a result of PCR research, chicken DNA (Gallus gallus) was found in six out of ten samples of meat products, but semi-quantitative analysis excluded one meat product, since the amount of the desired component was less than one percent. All ten samples were also subjected to organoleptic evaluation, physical and chemical studies, luminescent microscopy, and the determination of safety indicators (the number of chemical elements, pesticides, antibiotics, and radionuclides). The results of comprehensive research did not reveal any deviations. Thus, the method of polymerase chain reaction allows you to determine the type of raw materials in the composition of minced meat products, finely ground semi-finished products, including those subjected to heat treatment. To accurately confirm the presence of falsification of meat products detected by PCR-RV, not only qualitative analysis, but also quantitative analysis is necessary.
An analysis of the results of equine leptospirosis diagnostics by methods used in practice in state veterinary laboratories of the Russian Federation (bacteriological, serological (microagglutination reaction and enzyme-linked immunosorbent assay (ELISA)), molecular genetic (polymerase chain reaction method) for the period 2018-2020 is presented in the article. The veterinary laboratories of the Russian Federation received 225,582 horses blood serum samples for research on leptospirosis, for which research was carried out in the microagglutination reaction – 1,516,087, in ELISA – 1,039, 12,770 samples reacted positively. The analysis of the reported data for the last three years in the 4-vet form showed that the epizootic situation in equine leptospirosis in the Russian Federation remains difficult. The level of infection of horses with Leptospira averaged 5.7%. In 2020, the largest number of positive responders in microagglutination reaction were detected in 9 regions; among the studied animals, specific leptospirotic antibodies were found from 1.6% to 65.0% of cases. The dominant serogroups of leptospira in horses in the Russian Federation are Icterohaemorrhagiae and Grippotyphosa, up to 34% and 19.7%, respectively. Over the past three years, 1,907 urine samples from horses have been examined by dark-field microscopy; live leptospira have been found in only 1 case. To improve the epizootic situation in horses leptospirosis in Russia, it is necessary to increase the number of bacteriological and molecular biological studies for the timely detection of the causative agent of the disease – L. interrogans. In disadvantaged regions, it is necessary to use antileptospirosis vaccines in accordance with the specific etiological structure of animal leptospirosis, which is relevant for a specific territory.
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