From Big Medical Encyclopedia

AGRESSINA (Latin aggressio — attack) — the factors of virulence, various by the nature and the mechanism of action, providing an invasion of pathogenic microorganisms, their reproduction in fabrics and distribution in an organism.

The term «agressina» offered in 1905 Mr. Bayl (O. Bail). In his opinion, And., increasing virulence of microorganisms, promote their proliferation and distribution in fabrics.

In 1900 — 1911 Bayl et al. put a number of experiences with infection of animals with a bacillus of a malignant anthrax, pasterellama, a cholera vibrio, a typroid stick, a pneumococcus, a streptococcus, staphylococcus, etc. found that filtrates of the exudates formed in an abdominal or pleural cavity and also in the struck tissues of the infected animals, added to cultures of the corresponding bacteria, increase their pathogenicity. These filtrates did not contain either microbes, or toxins and in itself in the tested doses were harmless to animals. Bayl explained their action with presence at them of special substances — And., which are produced pathogenic a mikroor by ganizm in tissues of the infected owner, but not in cultures.

And., across Bayl, are characterized by the following properties:

1) sublethal doses of bacteria at addition to them And. kill animals;

2) the lethal dose of microorganisms causing drift of infectious process at presence And. causes bystry death of animals with characteristic defeats woven an organism;

3) addition A. to bactericidal serums (anticholeraic, antityproid) eliminates their bacterolytic action; 4) injection And. peculiar and much more effective immunity, than inoculation of the killed bacteria is reproduced. At the same time on And. both at immunization, and at an infection antiagressina which play an important role in the mechanism of antibacterial immunity are formed. Further it was shown that

A. products of growth of bacteria or their autolysis which can be allocated from cultures are actually. Addition to a sublethal dose of live bacteria of the killed cultures can cause the same fatal infection, as well as addition A.

At the same time exudates contain usual bacterial antigens. It turned out that at increase in their dosage by 2 — 3 times And. can cause the death of animals; besides, characteristic aggressive action can be caused by toxic products of bacteria.

By detailed studying of properties of the exudates received from infectious patients and from the infected experimental animals, it is established that one of factors of their aggressive action are their specific anti-opsonic properties. The same anti-opsonic effect was gained during the testing of the extracts prepared from various bacteria.

The microbic substances received from highly virulent bacteria and possessing aggressive action were called by N. Ya. Chistovich and B. A. Yurevich (1908) antiphagins, and Rozenau (E. S. of Rosenow, 1907) — virulinam. Under the name of agressin, antiphagins and virulin, obviously, the identical pathogenic substances emitted by bacteria both in vitro, and in vivo were described.

Bayl's assumption of existence of special substances played a positive role in studying of mechanisms virulence (see) pathogenic bacteriums.

Results of numerous researches showed that factors of aggression of pathogenic microorganisms are:

— microbic enzymes (hyaluronidase, a coagualase, fibrinolysin, a collagenase, a lecithinase, leukocidins, etc.) which promote an invasion of bacteria and help them to resist to defense reactions of an organism. [The role of these enzymes is visible from the following examples. Durant - Ray - nals (F. Duran-Raynals, 1942) described a so-called diffusion factor which was enzyme — hyaluronidase. Highly virulent bacteria (streptococci, causative agents of gas gangrene, etc.) produce hyaluronidase, edges, splitting hyaluronic acid, reduces viscosity of connecting fabric and thus promotes implementation of bacteria and their distribution in fabrics. The coagualase allocated by nek-ry virulent bacteria causes coagulation of plasma with release of fibrin which, enveloping bacteria, protects them from phagocytes and antibodies];

— the non-toxic components located on a surface of microbic cells (type-specific polysaccharides of capsules of pneumococci, polypeptide of D-glutaminic acid, the capsule of an anthracic bacillus, the M-protein of hemolitic streptococci, etc.), overwhelming immunological reactions of a macroorganism;

— microbic toxins (exotoxins and endotoxins) which cause damages to sensory cells and oppress defense reactions of an organism, damaging phagocytal cells up to their final fracture.

Along with the specified factors of aggression of pathogenic microorganisms it is necessary to consider also purely biochemical features of bacteria providing reproduction of their in vivo.

See also Bacteria , Infection .

Bibliography: Zhdanov V. M. Infektion, Mnogotomn. the management on mikrobiol., WEDGE. And 9PID. infekts. diseases, under the editorship of N. N. Zhukov-Verezhnikov, t. 4, page 17, M., 1964, bibliogr.; Zilber L. A. Fundamentals of immunology, page 52, M., 1958, bibliogr.; Petrovsky V. G. Problema of virulence of bacteria. L., 1967, bibliogr.; Bail O. Bakterienagresstne, Handb. pathogen. Mikroorgan., hrsg. v. W. Kolleu. a., Bd 2, T. 1, S. 635, Jena u. a., 1929, Bibliogr.; Topley W. W. a. Wilson G. S. Principles of bacteriology and immunity, v. 2, Baltimore, 1964, bibliogr.

A. V. Ponomarev.