From Big Medical Encyclopedia

GERM-FREE ANIMAL (Latin sterilis sterile; synonym: amicrobic animals, sterile gnotobionta, axenic animals, aseptic animals) — animal, free from endo-and ekzoparazit, and also the microorganisms which are a part of normal microflora of an organism.

With. receive by artificial continuation of prenatal sterile isolation of a fruit in its post-natal period lives. Theory and methods of receiving Page. develops gnotobiologiya (see) — section of experimental biology and medicine. Experiments from Page. carry out at the solution of many fundamental problems in the field of immunology, bacteriology, virology, parasitology etc.

Under natural conditions all animals and the person after the birth become carriers of normal microflora, edges occupies them integuments, upper respiratory tracts, went. - kish. path, etc. Therefore practically in all experiments with a germ-free animal control animals are usual, i.e. animals with normal microflora. At the same time in some cases, napr, during the modeling of microflora of the person in intestines of a germ-free animal, studying of interaction of in vivo of two and more microorganisms which are not colonized in an enteral path of ordinary animals, receiving specific immune serums, free of normal antibodies to nonspecific antigens, infection with pathogenic microorganisms to the Crimea ordinary animals are insensitive, etc., only a germ-free animal is used.

The majority of the highest animals under natural conditions need in symbiosis (see) with normal microflora, edges are provided in some cases by an organism of the owner with vitamins, nek-ry amino acids, digestive enzymes, etc. Therefore depending on conditions of cultivation of Page. on growth and development can or not differ from ordinary animals (a rat, a mouse, a dog, a cat), or to surpass them (chickens, the Japanese quails, pigs, monkeys), or to lag behind them (Guinea pigs, rabbits, kids, eanlings). Ruminants in this connection they are grown up in sterile conditions only before the period of independent food (chewing gum) especially need symbiosis with microflora.

For receiving Page. make a hysterectomy or its opening for the purpose of extraction of a sterile fruit, the fruit or oosperms of birds or insects after preliminary decontamination of their surface incubate, and then grow up in special insulators. Diets for feeding of Page. make thus that partial destruction of vitamins and nek-ry other substances after thermal or radiation sterilization was compensated.

Gnotobiologichesky and other methods do not allow to receive Page., if they were infected in the prenatal period of life with the microorganisms breaking a placental barrier or the oncogenous viruses which are transmitted in the «vertical» way. However it is established that amicrobic rats of lines Fischer, Spreyg — Dauli and Vee-is old are free from such viruses. In some cases, by decontamination antibiotics, receiving axenic animal, but not sterile is possible. This method at the corresponding indications is applied also in a wedge, medicine. Considering a possibility of infection in the embryonal period, subject to especially careful and comprehensive control colonies of the animals intended for receiving firstgeneration of Page. The last also shall undergo veterinary, microbiological and immunological inspection.

The animals divorced from generation to generation in the natural way in a sterile state call alpha gnotobiontami.

Comparative study of intact Pages. and showed ordinary animals that absence at Page. normal microflora is the prime cause of emergence of a hypoplasia at them limf, fabrics, in a cut the quantity immunoglobulin - the producing cells is sharply lowered. Therefore in blood serum and nek-ry secrets of Page. concentration of immunoglobulins, especially IgG, is much lower, than at usual. The immune system of Page is most underdeveloped., raised on a water-soluble bezantigenny diet; sterilization of food is carried out by means of filtering via the millipo-rovy filter (see. Bacterial filters ).

Immunol. features of Page. are caused by considerable decrease in intensity or total absence of an exogenous antigen challenge. At the same time their genetically determined immune potential is completely kept. E.g., rejection hallo - and heterografts at a germ-free animal happens in the same terms or even slightly earlier, than at ordinary animals.

In radio biological experiments it is revealed that auto-or the exogenous infection complicating a current radial illness (see) at ordinary animals, is absent at Page. It was very important during the studying of questions of a pathogeny and treatment of radiation defeat. The mice with normal microflora who received a lethal exposure dose and for treatment to-rykh allogenic marrow was used, after recovery perish from a radial illness as a result immunol. the conflict — reaction a transplant against the owner (see Incompatibility immunological), and amicrobic mice in a similar experiment survive. It began to be used at treatment of leukoses: patients, it is total or selectively dekontaminiro-bathrooms from automikroflor (see. the Selection decontamination ), after radiation and transplantation of allogenic marrow do not perish from reaction a transplant against the owner.

The rational scheme of an antibioticotherapia for the purpose of prevention of development of autoinfection in patients with sharply lowered resilience to infection in the course of immunodepressive therapy, and also at a granulocytopenia and other serious conditions is fulfilled on Page. after their association with an indestinal flora of the patient.

One of advantages alpha gnotobmontov before ordinary animals is absence in their organism latentno of the persistent viruses and bacteria capable to cause an open infection. Studying of features of Page., development on them of methods of management of microflora of an organism of the owner promote wider use of achievements of a gnotobiologiya in surgery, oncology, pediatrics, etc.

The term «germ-free animal» is applied sometimes as a synonym of the term «infertile animals».

See also Sterilization .

Bibliography: Chakhava O. V., Mountain E. M and Ruban of Page 3. Microbiological and immunological bases of a gnotobiologiya, M., 1982, bibliogr.; The germ-free animal in research, ed. by M. E. Coates, L. — N. Y., 1968; International gnotobiological symposium, Folia microbiol., v. 24, Xv 1, 1979; Recent advances in germfree research, Proceedings of the 7 th international symposium on gnotobio-logy, ed. by S. Sasaki, Tokyo, 1982.

O. V. Chakhava.