RU-2861301-C1 - BACTERIAL STRAIN ESCHERICHIA COLI - PRODUCER OF ADHESIVE ANTIGENS K88ac (F4ac), 987P (F6) AND HEAT-LABILE (LT) TOXIN

RU2861301C1RU 2861301 C1RU2861301 C1RU 2861301C1RU-2861301-C1

Abstract

FIELD: veterinary microbiology. SUBSTANCE: proposed is a bacterial strain Escherichia coli, which is a producer of adhesive antigens K88ac (F4ac), 987P (F6), heat-labile (LT) and heat-stable (ST) toxins, used as a production strain for the purpose of creating prophylactic, diagnostic and therapeutic preparations against colibacillosis, deposited in the "All-Russian Collection of Microorganism Strains Used in Veterinary and Animal Husbandry" under the number VKSHM-B-23PD. EFFECT: expansion of the range of Escherichia coli strains suitable for the manufacture of vaccines, diagnosticums, hyperimmune therapeutic sera and globulins against colibacillosis. 1 cl, 7 tbl, 4 ex

Inventors

MOTORYGIN ANTON VALEREVICH
PIROZHKOV MIKHAIL KONSTANTINOVICH
Lenev Sergei Vasilevich
Rusanov Ivan Anatolevich
Abrosimova Nadezhda Sergeevna
Soltynskaia Irina Vladimirovna
Krylova Ekaterina Viktorovna

Dates

Publication Date: 20260504
Application Date: 20250527

Claims (1)

A strain of Escherichia coli bacteria - a producer of adhesive antigens K88ac (F4ac), 987P (F6), heat-labile (LT) and heat-stable (ST) toxins, used as a production strain for the purpose of creating preventive, diagnostic and therapeutic drugs against colibacillosis, deposited in the "All-Russian collection of strains of microorganisms used in veterinary medicine and animal husbandry", under the number VKShM-B-23PD.

Description

The invention pertains to the field of veterinary microbiology, specifically to the section on studying the biological properties of microorganisms, including morphological, cultural and molecular genetic methods, serological identification, determination of virulence and antibiotic resistance of Escherichia coli strains, and concerns a new strain of Escherichia coli containing genetic determinants of the adhesive antigens K88ac (F4ac), 987P (F6), heat-labile LT and heat-stable ST toxins and stably producing these virulence factors. The strain can be used as a protective antigen in the manufacture of vaccines, as well as in the production of hyperimmune therapeutic sera and globulins against colibacillosis in animals. The invention makes it possible to expand the arsenal of strains intended for the production of agents for the specific prevention and treatment of colibacillosis in farm animals, with high stability, antigenic, immunogenic and protective activity. The causative agent of escherichiosis - enteropathogenic strains of E. coli have a complex antigenic structure, including somatic O-antigens, capsular polysaccharide K-antigens, flagellar H-antigens and multiple virulence factors, such as endotoxin, verotoxin, heat-labile and heat-stable enterotoxins, adhesive antigens and hemolysins, which determine the characteristics of the course and variety of clinical manifestations of escherichiosis. The main condition for the development of the infectious process in escherichiosis is oral infection with enteropathogenic strains of Escherichia, adhesion of the pathogen in the small intestine, abundant reproduction, accumulation of toxins, penetration of the pathogen in some cases through the intestinal wall and further development of pathological symptoms of varying intensity. Colonization of the small intestine by the pathogen is a necessary step in the development of any form of colibacillosis. Escherichia coli bind tightly to the villi of the intestinal mucosa using adhesion antigens. Cells lacking adhesion antigens are removed from the mucosa by the movement of food particles. Thus, adhesion antigens of Escherichia coli play a leading role in the pathogenesis of the disease. Equally significant is the role of E. coli enterotoxins, which accumulate in the intestine. It has been established that strains containing adhesins typically also produce enterotoxins [1]. Studies of the pathogenesis of diarrhea caused by E. coli have led to the significant conclusion that adhesive antigens and enterotoxins are the two main virulence factors of enteropathogenic E. coli, especially since they have never been detected in nonpathogenic E. coli . Adhesion antigens such as K88 (F4), K99 (F5), 987P (F6), F41, Att25, F18, and others are known in E. coli strains that cause escherichiosis in animals. It has been established that Escherichia coli strains can simultaneously synthesize several adhesins. Escherichia coli strains with multiple adhesins better colonize the small intestine of newborn animals compared to E. coli producing one of the adhesion antigens [2, 3]. The K88 antigen is a heat-labile fimbria-like protein that forms on the cell surface as thin filamentous structures—pili—both in vivo and in vitro on standard nutrient media at a cultivation temperature above 18°C and denatures when heated to 100°C. K88 fimbriae are arranged on the bacterial cell in an X-shape and are 0.1-1 μm long and 2.1 nm in diameter. There are approximately 100 of them on a single cell. The K88 adhesion antigen consists of 95% protein, 3-4% lipids, and 1% carbohydrates. The K88 adhesin is characterized by antigenic heterogeneity and is formed from four different factors (a, b, c, d), which never coexist, with combinations of ab and ad occurring less frequently and ac more frequently. The molecular mass of the K88ab adhesin is 27.54 kDa, while those of K88ac and K88 ad are 25 and 26 kDa, respectively. All three variants of the K88 antigen have an isoelectric point of 4.2 and consist of separate identical protein subunits that are arranged in a strictly linearly ordered system, forming the basis of the fimbrial structure. Synthesis of this antigen is determined by F-class transmissible plasmids with a molecular mass of 51–90 mDa [4–6]. Adhesion antigen 987P is a long, straight fiber with an outer diameter of 7 nm and a length of up to 2 μm. Adhesin 987P is a heat-labile protein consisting of subunits with a molecular weight of 22.5 kDa and an isoelectric point of 3.7. Synthesis of this antigen is encoded by chromosomal DNA. Production of antigen 987P in vitro depends on the strain's growth conditions. During its cultivation, the addition of 5% defibrinated ram blood to the medium is recommended [7, 8]. Heat-labile (LT) and heat-stable (ST) enterotoxins have been identified in enterotoxigenic Escherichia coli. The ability to form enterotoxins is determined by the presence of transmissible (conjugative) Ent plasmids with a molecular weight of ap