The article presents the results of studies on the detection of Streptococcus suis by real-time polymerase chain reaction. Isolation and species identification of the studied isolates of streptococci was carried out according to morphological, cultural, biochemical and biological properties by conventional methods. The study of cultural characteristics of growth was carried out using conventional bacteriological methods on the brain heart infusion broth (BHI) and BHI agar with the addition of 5% sheep blood (blood BHI agar). To confirm biochemical properties as a confirmatory method, API 20 STREP test kit (bioMerieux, France) was used. In addition, to differentiate S. suis from the non-pathogenic species of streptococci, the hemolysis test was used. As a result of the studies, it was found that the use of the real-time PCR (polymerase chain reaction) method makes it possible to detect S. suis in an amount of 1 x 104 genome copies in the sample. All described validation parameters for the qualitative detection of S. suis DNA by real-time PCR meet international requirements, which guarantees accurate and reliable results. In Ukraine only a diagnostic test kit for convential PCR has been developed for the detection of swine streptococcosis. This approach is more time consuming and complex in comparison with the real-time PCR approach. We recommend that diagnostic laboratories implement this method in their practice. This will increase the number of effective diagnostic tools available to veterinarians on pig farms when they order laboratory tests. The high analytical sensitivity limit of a test is an essential parameter when screening is the focus, and obtaining false negative results causes a risk of the development of infection process among pig populations within infected herds. Our study showed that microbiological diagnostic methods to determine morphological and cultural properties can identify S. suis at the genus level. Determination of biochemical properties using the API 20 STREP test kit can be used to identify S. suis 1 and 2 serotypes. The conventional method and real-time PCR have 100% specificity and can be used to identify S. suis of different serotypes. Real-time PCR is a 2 to 4 times more sensitive limit than conventional PCR depending on the serotype being studied, and can be used to more accurately identify streptococcal DNA. It was found that the use of the real-time PCR method makes it possible to detect S. suis in an amount of 1 x 104 copies of the genome in the sample. Additionally, it was found that all the studied validation parameters of the qualitative method for determining S. suis DNA by real-time PCR meet international requirements, which guarantees accurate and reliable results.
Living vaccines are not widely used in practice to prevent and control brucellosis in domesticated reindeer. Brucellosis vaccines from strains 19 or 82 are characterized by a high level of reactogenicity and lead to complications in vaccinated animals. When studying the reactogenic properties of the vaccine from the B. suis 245 strain in the experiment on reindeer, the reaction of the body of domesticated reindeer to the subcutaneous injection of brucella from the B. suis 245 strain was considered. At the same time, no significant differences were observed when the vaccine was administered at a dosage of 10 and 50 billion microbial cells, and the size of edema in millimeters was fixed at the level of 39.0 ± 3.5 and 44.1 ± 2.6, respectively (P> 0.05). The dynamics of the body temperature of animals depending on the method of administration and dose of the vaccine, regardless of the dosage, body temperature, like other indicators of a physiological nature, remained within the normal range. It was found that in the early stages after vaccination, the indicators of the physiological state of the animal’s body are determined by whether the oral or subcutaneous method of administration of the vaccine was used. When vaccinated by the subcutaneous method, reactogenicity was less pronounced with the introduction of 5 billion microbial cells, compared with a dose of 50 billion microbial cells.
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