ADENOVIRUSES (Greek aden — gland + viruses) — the group of causative agents of respiratory and other diseases including about 50 versions (serotypes) allocated from people, monkeys, dogs, a cattle, rodents and birds. Rezistentna to effect of ether and acids, epiteliotropna possess the general group complement-linked antigen.
Causing mainly respiratory diseases, And., unlike other respiratory viruses, strike other systems of an organism much more often: conjunctiva, limf. nodes, went. - kish. a path (see. Adenoviral diseases). Easily breaking a gastric barrier in connection with resistance to acids, And. intensively breed in intestines.
First strains And. became known thanks to Rowe, Hübner, Gilmore, Parrott and Ward's researches (W. P. Rowe, R. J. Huebner, L. Gilmore. R. Parrott, T. E. Ward, 1953) devoted to studying of the cytopathic agent allocated from adenoid tissue of the person. The adenoid fabric extracted in the operational way was cultivated in the rotating test tubes in the environment containing mix of a cow amniotic fluid (85%), embryonal extract (10%) and serums (5%). It was noticed that in such culture there is a spontaneous degeneration of cells on 7 — the 10th day of observation. The subsequent passages of the degenerating fabric on cells of the intertwined HeLa line and other fabrics revealed existence of the virus having peculiar properties. The allocated new virus strains from clinically healthy children were carried to group of «latent» and received the name of «agents of an adenoid degeneration». It was soon established that the same viruses often are found not only in adenoid tissue and almonds of clinically healthy children, but also allocations of patients with acute pharyngitis and conjunctivitis. Then viruses received the second name «adenoid faringo-conjunctival viruses».
Irrespective of the first researchers Hilleman and Verner (1954), studying an etiology of diseases of a respiratory organs at the military personnel, found that a part of the diseases proceeding as acute katar of respiratory tracts and atypical pneumonia is connected with the new, earlier unknown virus called by R1-67. This virus managed to be allocated from patients and to grow up in culture of fabric, in particular in cells of HeLa. Further both groups of researchers showed similarity of the studied viruses and found that they can be allocated both from healthy people, and from patients with various diseases with the preferential defeatist of respiratory tracts.
Initial names of viruses were replaced in 1956 with the general group name «adenoviruses». In a crust. time is known not less than 32 serotypes And., allocated from the person.
And. have size from 70 to 90 nanometers. The internal structure of a virus particle — virion — consists of an outer proteinaceous membrane and internal subunits size apprx. 7 nanometers (fig. 1 and 2). Number of the subunits called by capsomeres, at all investigated And. has a constant and it is equal to 252. Virions have cubic isosaedralny structure. And. contain two-filamentous DNA about a pier. weighing 20 — 25 million dalton, making 12 — 14% of mass of virion with the smaller content of adenine and thymidine (43%), than guanine and a tsitozin (57%). In case of the expressed oncogenous activity (the 12th and 18th serotypes) the ratio of guanine to a tsitozin falls to 48 — 49% against 50 — 60% at not oncogenous A. Belok makes 87% of mass of the purified virion about a pier. weighing less than 35 000. Lipids, carbohydrates, own enzymes are absent.
Action of physical and volumetric factors. And. are inactivated by warming up and t ° 56 ° within 5 min. or 20 — min. at t ° 50 °; keep activity within 7 days at t°36 °, 14 days — at t ° 22 — 23 °, 70 days — at t ° 4 °. Are steady in the acid zone pH from 6,5 to 3,0; at pH 1,5 — 2,5 are partially inactivated within 30 min. at t ° 36. At the room temperature well remain in the zone pH from 6,0 to 9,5, borders of pH are more sensitive to increase alkaline, than acid. Rezistentna to organic solvents (ether, chloroform, a fluorokarbon), and also to trypsin, papain, ribonuclease, a deoxyribonuclease and to bile.
Antigenic structure. By means of a chromatography and an electrophoresis three various soluble antigens differing on immunological properties and connected with various morphological subunits of a virus are emitted.
1. A-antigen, hexone — group, the general for all serotypes of a virus the antigen localized in 240 capsomeres of a capsid each of which borders on six next capsomeres that defined the name of antigen (hexon). Antibodies against the purified geksonny antigen neutralize infectious properties only of a homologous serotype. At the same time this serum reacts in reaction of binding complement with any heterological serotypes since as a part of geksonny antigen there are two reactive groups, one of which stimulates education group-specific, and another — type-specific antibodies.
2. V-antigen, oxetane resin — the toxic antigen causing rounding and crowding (aggregation) of sensory cells of single-layer culture and department of cells from the surface of glass. It is localized in the capsomeres located at top of twelve angular sites of virion, each of which borders on five next capsomeres (pepton). It is sensitive to effect of trypsin. Inhibits activity of interferon (see) and increases weight of the associated respiratory infections.
3. S-antigen — nitevy (fiber) antigen, has morphologically the form of the thread with a nodal thickening attached to pentonny antigen. Represents type-specific antigen, it is steady against effect of trypsin, promotes adsorption And. on erythrocytes of a monkey or rat and their agglutination.
Cycle of reproduction. Adsorption And. on sensory cells of fabric culture takes 4 — 6 hours then the virus gets into cytoplasm by means of a pinocytic. Release of nucleoid (deproteinization) is carried out in pinotsitarny vacuoles within 60 — 90 min. after what virus DNA is transported to a kernel of a cell. Stage of latency of a reproduction proceeds from 13 to 15 hours when in a kernel DNA is synthesized, and on cytoplasmatic ribosomes — virus proteins. In 16 hours after infection there are mature structural particles which assembly happens in kernels of cells. But more than 10 — 15% of virus DNA and proteins of fabric culture are used for synthesis of virions, all other weight stimulates defeats of kernels of a cell and disturbance of synthesis of cellular DNA and proteins, with the termination of cell fission in 10 — 11 hours after infection of culture.
The maximum exit of a virus is provided in case of massive infection and an incubation of culture before full development of cytopathic defeats. For receiving the maximum exit of a virus from enough remained cells they are destroyed repeated 3 — 6-fold freezing and thawing, homogenized ultrasound or a mechanical grinding. At the same time concentration of a virus fluctuates depending on a serotype from thousands to billions of particles in 1 ml of an intercellular lymph.
Reproduction And. in fabric cultures very often is followed by parallel development in kernels of cells of small virions with a diameter about 200 And, ikosaedralny symmetry, adenoassotsiirovanny viruses which received the name (see). On an antigenic structure and biological properties they have nothing in common with adenoviruses. Reproduction of adenoassotsiirovanny viruses is in a complete dependence from presence And., appeared «assistants» to these, agents, not capable to independent development.
Cellular defeats. The cells infected with adenoviruses are rounded and create the uviform accumulations of various size facilitating recognition of agents of this group. Cytopathic changes are followed by increase in glycolysis and accumulation of the organic acids acidifying an intercellular lymph.
A cellular lysis is absent and the infected cells a long time keep viability.
In the course of a degeneration of cells under action And. distinguish two phases (fig. 3): the first is connected with toxic effect, the second — with true reproduction of viruses, a cut occurs in kernels and in cytoplasm. At the same time And. form intranuclear inclusions of virus particles which make agglomerates of a kristallopodobny structure (fig. 4).
Pereira and Valentin's Elektronnomikroskopichesky researches (N. of G. Pereira, R. The page of Valentine, 1958) showed that one cytopathic dose of a virus contains from 10 to 103 virus particles.
Reproduction in the intertwined lines of cells of KV, HeLa, and also in renal cultures of monkeys under an agar covering is followed by formation of the colonies (plaques) seen by an eye around the struck cells.
The hemagglutinating properties. All serotypes And. the person, except type 18, erythrocytes of monkeys are capable to agglutinate a Rhesus factor or rats. On this sign And. it is possible to classify on the following four subgroups: the first includes nine serotypes (3, 7, 11, 14, 16, 20, 21, 25, 28) agglutinating only erythrocytes of monkeys; the second includes twelve serotypes (8, 9, 10, 13, 15, 17, 19, 22, 23, 24, 26, 27) agglutinating erythrocytes of rats; the third — six serotypes (1, 2, 4, 5, 6, 12) agglutinating erythrocytes of rats after interaction with immune adenoviral serum against other types (e.g., 6 types); the fourth includes the serotype 18 not capable to hemagglutination.
Pathogenicity for the person and animals. Unlike other respiratory viruses, And. breed not only in a cylindrical ciliary epithelium of upper respiratory tracts, a trachea and bronchial tubes, but also in under a mucous membrane. With participation And. development of the acute respiratory infection proceeding with the phenomena of quinsy, pharyngitis, cough, a fever, baud in muscles, a headache at non-constant cold and temperature increase is most often connected (see. Adenoviral diseases, Respiratory viral diseases).
The first seven serotypes, and also types 14 and 21 were the most frequent activators. At babies heavy pneumonia, occasionally with a detailed outcome, caused by serotypes 1, 2, 3, 7 and 7a often develops.
Until recently the provision on absence was considered conventional at And. the person of pathogenicity for animals.
Numerous experiences of infection of many species of mammals, including monkeys, gave either negative, or doubtful results. It remains fair for usual conditions of receiving an experimental infection, however at change of methods of a research new data are obtained. Jennings and Betts (A. R. Jennings, A. O. of Betts, 1962) adapted adenoviruses of 1, 2, 4 and 6 serotypes to culture of tissue of pork kidney. Then intratrakhealno infected the pigs born and who are grown up in sterile conditions in amicrobic external environment. For the 4th day after infection at the majority of animals bronchial pneumonia with the expressed lymphoid hyperplasia developed.
Intranasal or hypodermic infection of adult Syrian hamsters, dogs, rabbits, and also newborn mice and rats with viruses 3, 4, 5, 7, 12, 18 of types led to development of asymptomatic infections.
Infection of newborn hamsters with a serotype 5 caused, according to Pereira, the death of animals in 4 days with typical damages of lungs and allocation of a virus. Pathogenicity for the monkeys who are allocated from them And. it is not proved.
In a number of laboratories are quite often allocated And. from patients with a viral hepatitis both from a calla, and from blood. Perhaps, And. are satellites of the true activator, but it is impossible to exclude also existence at some strains of a certain gepatotropizm. L. G. Rudenko's work, etc. deserves attention (1972) where the susceptibility of newborn hamsters aged to 5 days to adenovirus of 1 type (a strain of 1237) is shown at hypodermic infection. At the infected hamsters hepatitis develops and there is a selective reproduction of a virus in a liver.
Oncogenous properties. Ability And. the person to cause development of malignant tumors (sarcomas) in the newborn Syrian hamsters infected subcutaneously with a massive dose of an active virus it is for the first time revealed at a serotype 12. Oncogenous properties are confirmed at seven other types A now. the person, and also at six types from monkeys and at one from birds. The greatest activity was shown by serotypes 12, 18 and 31; type 12 caused tumoral growth, in addition to hamsters, also in newborn rats, wild African rodents is Mastomys and some lines of mice. In the formed tumors infectious particles And. no.
Malignant transformation of cells was observed also in experiences of in vitro at infection with type 12 of normal epithelial cells of culture of kidneys of newborn Syrian hamsters, and also fibroblasts of a germ of a rat. In 3 — 10 weeks after inoculation of cultures a massive dose of a virus growth of tumor cells, free from an infectious virus developed. The cells transformed by in vivo or in vitro contained two new antigens: T-antigen (neoantigen) and transplant (TSTA) antigen. Their products are induced by a part of DNA of oncogenic A. Vesm a big pier. the weight of DNA of adenovirus (more than 20 million dalton) provides a possibility of coding of synthesis more than 50 various proteins. The T-antigen found irregularly in early stages of a usual cytolytic infection constantly is present at tumor cells and is with firmness transferred in vitro at their cultivation. It is found in reaction of binding complement and on immunofluorescence with serums of hamsters with the developing tumor which do not interact with structural proteins of viruses. T-antigen is unstable to heating, influence of acid and alkali, does not contain RNA or DNA, has a pier. weight 78 000 dalton.
On antigenic properties distinguish T-antigen of group A (high-oncogenous adenoviruses of 12, 18 and 31 serotypes) and group B (slaboonkogenny adenoviruses of 3, 7, 11, 14, 16 and 21 serotypes). Attempts to find T-antigen group And yes In in tumor cells and antibodies, homologous for them, in serums of the people having cancer various localization yielded a negative take. In tumoral tissue of hamsters this antigen is present at very high concentration and easily it is found by means of fluorescent antibodies in each tumor cell.
Allocation of adenoviruses is carried out by infection of sensitive fabric cultures separated from a nasal cavity, a pharynx, a conjunctiva and also the intestinal contents. And. breed better (with development of characteristic cytopathic changes) in the intertwined epithelial cultures (HeLa, KV, NER-2), and also in primary culture of an embryonal kidney of the person; breed in primary epithelial cultures of a human trachea, amnion, renal tissue of monkeys and rabbits more weakly. Optimum method of allocation — infection of primary cellular culture of an embryonal kidney of the person with passages on the intertwined lines after adaptation of a virus.
Serological identification of the allocated strains. For reference to group A. the allocated agents are differentiated immunological by establishment of the general group antigen in RSK or in reaction precipitation (by a method diffusion in agar gel). Definition of a serotype is carried out by means of hemagglutination-inhibition reaction or neutralization. For identification of a serotype of the allocated strain determine its belonging to one of four subgroups by hemagglutination then put hemagglutination-inhibition reaction (RTGA) with the immune serums of rabbits or horses processed by a kaolin and exhausted by erythrocytes, sensitive for this subgroup. Results of RTGA check in reaction neutralization on fabric cultures with homologous immune serum (see. Virologic researches).
In modern classification of viruses of the person A. hold independent position among the DNA-containing viruses, being accurately differentiated from other fellow members of this group on properties of virions.
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