SALMONELLA ABORTUS EQUI BACTERIAL STRAIN FOR DEVELOPMENT OF CONTROL MEASURES

Abstract

The isolation of pure cultures of the bacteria Salmonella abortus equi from biological materials, its identification, and the study of their properties are necessary for making a diagnosis, developing control measures and preventive measures. The cultural properties of the pathogen were studied by plating on liquid and solid nutrient and differential diagnostic media (meat-peptone broth, meat-peptone agar, Endo agar, Olkenitsky's medium). The biochemical properties of the isolated cultures were determined by the ability to ferment carbohydrates on Hiss media with mannitol, lactose, maltose, sucrose, glucose, and dulcite. Motility - by plating on semi-liquid agar. The morphology of the cultures was determined by viewing Gram-stained smears under microscopy. The antigenic structure of Salmonella cultures was determined using monoreceptor Salmonella sera. The bacterial strain Salmonella abortus equi BN-12 corresponds in cultural, biochemical and antigenic properties to the characteristic features of the causative agent of salmonella abortion in horses.

The virulence of the bacterial strain was assessed on outbred white mice (n=20) weighing 18-20 g. Virulent activity LD50 was determined by the Kerber method.

Genetic identification was carried out by determining the nucleotide sequence of a fragment of the 16s rRNA gene at the Genomics Shared Use Center of the Institute of Chemical Biology and Physics of the Siberian Branch of the Russian Academy of Sciences and the Department of Biotechnology of the Federal State Budgetary Institution "VGNKI". The PCR method established 100 % identity of the analyzed sample sequences with the nucleotide sequence of the 16S rRNA gene of Salmonella enterica. Pathogenic for white mice. The lethal dose is 400 million microbial cells in 1 ml. The research results allowed the bacterial strain Salmonella abortus equi BN-12 to be deposited in the “All-Russian State Collection of Strains of Microorganisms Used in Veterinary Medicine and Animal Husbandry” of the Federal State Budgetary Institution “VGNKI” under the number VKShM-B-01PD.

An inactivated vaccine against salmonella abortion in horses with an immunomodulator was made from the bacterial strain Salmonella abortus equi BN-12. The immunobiological preparation was approved by Rosselkhoznadzor with the issuance of a registration certificate in 2019. The immunogenicity was 80 %. The vaccine has no analogues in Russia and is successfully used in the constituent entities of Russia and Kazakhstan. The strain is used in the development of bacteriophages for the diagnosis and treatment of horses with salmonella abortion.