General description.

The virus is comparatively small pathogen built with one type of nucleic acid (the DNA or RNA, though the viruses are, which they in their life cycle cross by phase the DNA as well as RNA). They are then particle which can not grow in numbers on artificial sbasis. They do not possess the own machinery of transmutation of matter. Virus can exist beyond cell however no metabolic transmutation set in him then. Virus' complete form, virion, is including nucleic acid particle, surrounded by proteins and possessing sure sometimes different macromolecular components. Different acellular infectious factors except viruses exist - folded only from RNA "wiroidy", "wirusoidy" and protein prion.

Several relating viruses' origins hypotheses' exist. According to first, viruses are pathological active particles from macroorganism. It reminds then cancer. Cancer cells come from from the same organism, but completely independent, pathological proprieties have and they behave how parasites. Some are careful that vegetable viruses can to come into being, under working sure internal stimuli, influencing on disorder of process of transmutation matter intracellular. According to second hypothesis, virus is the representative of primitive, precellular figure of life. Going out with foundation that viruses are on Earth the beginnings of life, some explorers would want it to be careful for transitory creatures between and creatures alive dead matter. Viruses show to "transpozon" sure analog. "Transpozon" " to dress if would" in protein areola and to make possible him penetrating to different cells, he would stand virus. Ale it can be also inversely - "transpozons" this retard viruses, which they lost areolae and ability of attacking different cells. To be so maybe also that there is no no relationship between them. It different conception takes out viruses from primitive, very simple, ale however independent organisms. They had initially they to use with supplies surrounding it habitat, and in measure appearing different, more folded cells, to enter with them in co-operation. Effect of this magnificent oneself the loss of independent by viruses and connected the takes over the function from multiplying "wirion" through cell the - the host.

Virus' counterplead be holds really after introduction his genetic material to cell. When virus foundling oneself his reproduction in cell begins. Process this be connected from infecting farmer's cell. In relationship with small size virus contains only very basic information relating his genom, control of reproduction as well as building of protein areola. He in the face of this during process of reproduction is in large degree dependent from the farmer's metabolic and structural features, adapting it in sure degree to one's needs. Clever virus is to introducing hereditary (profitable or destructive) changes in host's genomie. Viruses were it been possible to classify in support about organization possessed by it genetic material. Viruses' genetic material can step out in several forms: DNA one - or two-ply, RNA one - or two-ply as well as both DNA how and treat on different stage RNA the existence of wirionu. It beyond this makes fission on group in dependence from genus of infected organism: vegetable viruses, animal and bacterial.

VIRUSES's BUILDING

It marks the virions both the variety of shape and the size. They are considerably smaller than cell (about 28 - 200 nm) and moreover a lot of smaller genomy have. Nucleic acid is the particles of wirionu inside and be surrounded through protein "overcoat" called kapsydem, formed exactly from several sub - units protein "capsomers". Information relating forms contained "capsyd" is in structure "capsomers", and creating areola sets on principle assemble. The complex of areola from nucleic acid the called "nucleocapsyd", it is additionally surrounded with two-ply lipids including as well as lipids come from integument of the host's cell glikoproteins of virus origin integument often. Virus' integument is first entering in interactions from cell host and her origin element it influences on way of virus' as well as penetration infection cells inside. Specific playing in process sure part enzymes of infecting the host's cell can be the virion inside. Many viruses contain own polymerase, however retrovirus possess opposite "transcryptasis". Moreover "neuroaminidasis" in viruses step out, ripping which bond "glikozydowe" glikoprotein and "glicolipids" facilitate viruses the penetration of animal tissues as well as lysozyme which it makes possible penetration to cell bacterial viruses as well as her decomposition causes.

Pic. 1 - Diagram of structure virus particles.

The virus of madness (a) and the HIV (c) the adjacent shields, virus have closely Herpes simplex (d) it has faintly the adjacent shield, during when the adenovirus (b) it has not the shield. Viruses' size: (a) 180 nm, (b) 45 nm, (c) 100 nm, (d) 90 nm. The viruses possess sure symmetry of building. Viruses' symmetry it treats to nucleocapsid and not to whole virus from integument. We favour two basic types of symmetry:  

• "helix" - protein sub - units be arranged in helix ( it was it been possible graphically to compare to round staircase), which length depends from length of nucleic acid and width from size and packing up sub - units. The virus RNA of tobacco mosaic TMV is the example here  

• "icosahedron" - protein individuals create icosahedron

Pic. 2 - Patern of symmetry: icosahedron and helix.

PRINCIPLE of the VIRUS's REPRODUCTION

Basic problem what virus encounters on with its way in multiplying excitement to production of indispensable elements host's cell to producing virus' next particles is. The annexation is in this process first stage or also the adsorption of virion on the host's susceptible cell. Penetration sets then, which it depends on injection of wirionu or his nucleic acid to interior of cell. The initial phaze of duplication depends on adaptation the machinery biosynthesis' of the host's cell to synthesis of the nucleic virus' acid. Virus enzymes be produced. Duplication of the nucleic virus' acid is the next stage, and then the synthesis of protein sub - units areola and their folding as well as packing up in the virus' new particles the nucleic acid and liberation of their of cell.

Some indispensable enzymes in virus' genomie be coded to his duplication however the rest that is: systems assuring energy, ribosome, tRNA (with sure except) as well as enzymes activating amino acids be delivered through host's cell. First stage of the virus' duplication characterizes among virus and host with large peculiarity of interaction. The virus' particle possesses on one's surface of white which affect from specific superficial elements on cell with called receptors. Usually fulfil they in cell normal functions np. proteins forwarding or proteins this glicoprotein is or in case of influenza bacterial areola on erythrocyte. If receptor does not step out or be altered, virus can not adsorb and infection will not drop in - host becomes resistant on virus obviously until enabling him to mutated receptor adsorption mutation in virus will not drop in. Aggregation the virus can to set on unspecific road across fagocitose also or different processes of endocitose (general among animal viruses and vegetable).

Pic. 3 - The ways of penetration of viruses.

Process of the virus' penetration to inside the host's cell dependent it is from character this cell, particularly from her superficial structures in result of what the penetration sets in animal devoid the cellular wall cells differently than in vegetable and bacterial. The infection of cell is the example of compiled mechanism of penetration E. coli bacteriophage T4. Virion T4 possesses head structure, placed on stalk which ends with set of caudal strings. It strings these as first attach to the surface of cell and the shrink what was caused was the close relations the core of stalk to surface of cell then. The virus enzyme about character of lysozyme causes in cellular wall, through which the rise of small opening virus DNA penetrates. Possibility of removal of the nucleic virus' acid across working the restrictive being on terrain of cell enzymes on this stage exists yet. Yet viruses developed sure mechanisms, thanks which they can counteract this process - modify nucleic acids in similar way how host's cell or they brake working through specific whites restrictive systems. The specific mRNA in aim of rise of new virus proteins have to be created. Synthesis mRNA virus it depends from virus and his genetic material's type. In case when virus' genetic information state possible RNA is for production several solutions mRNA. When we have to deal with with including one-ply positive RNA virus (+), this marks that it serves directly as mRNA. In this she RNA be coded between different polymerase specific RNA for virus. Polymerase this causes the rise of negative thread complementarine initially, which it serves as matrix to production of larger quantity of positive threads then. If however one-ply negative RNA is exit genetic material (-) or two-ply RNA situation oneself it complicates somewhat because mRNA can not fulfil it function directly. To necessary mRNA came into being it is RNA - dependent polymerase RNA, which steps out in viruses and mRNA leads to synthesis. It retrovirus (viruses RNA) it was rejoined was thanks to mediation of DNA. The process of copying from RNA genetic information on DNA is this opposite transcription and the he under influence of enzyme sets opposite. After it infecting the cell, RNA of wirionu it be copied on dsDNA from passage by stage ssDNA. DsDNA serves as matrix to synthesis mRNA then. When rise possible mRNA is already the synthesis of virus proteins. Whites these belong to three main groups:

• the early whites about enzymic character, indispensable to duplication of the nucleic virus' acid, synthetised in small quantities  

• the late whites that is the proteins of virus overcoat, proteins structural, synthetised in large quantities  

• lytic whites which make possible unlocking host's cell and liberation virus' particles.

SYSTEMATIC of CHOSEN of FAMILIES VIRUSES:

• Poxviridae profile: the dsDNA, particle about shape of " brick", duplication in cytoplasm the representatives: the virus of the cow's smallpox, virus of true smallpox the called out diseases: true smallpox; used as laboratory viruses

• Herpesviridae profile: , kapsid surrounded with shield dsDNA, often stepping out latencia in host's cells, duplication in cellular nucleus representatives: Herpes simplex virus (HSV), Varicella - zoster virus (VZV), virus cytomegalia, virus Epsteina - Barr (EB) called out diseases: the ulceration of epidermis (HSV1) and the sexual organs (HSV2), windy smallpox, shingles, sure types of tumours

• Adenoviridae profile: dsDNA, without shield, duplication in cellular nucleus representatives: adenovirus (many types) called out diseases: contagion of respiratory roads and eyes, calling out with experimental animals the crayfish

• Poapovaviridae profile: circular dsDNA, 72 capsomers in capsid, the lack of shield, duplication in cellular nucleus the representatives: human viruses "brodawczaki" (papilloma) called out diseases: nipple of skin, mucous integument, connection from occurrence the crayfish of neck of uterus

• Hepadnaviridae profile: one complete thread of DNA about negative polarity from added particle the proteins to end the 5",, of particle about dimensions 42 nm having the shield the representatives creation thanks to presence of incomplete thread about positive polarity the circular structure of DNA: the virus of hepatitis of the type B the called out diseases: jaundice infectious

• Paramyxoviridae profile: ssRNA (-), particle having shield and appendix representatives: the virus paragrypy, virus of measles, virus RSV the called out diseases: the contagion of respiratory roads, measles, bronchitis * Orthomyxoviridae the profile: eight segments ssRNA (-), having shield and appendix, helikalny nucleocapsid representatives: the virus of influenza the called out diseases: influenza

• Reoviridae profile: 1012 segments dsRNA, ikosaedralne, without shield representatives: rotavirus called out diseases: babies' diarrhoea

• Picornaviridae profile: ssRNA (+), particle about spherical symmetry and dimensions 22-30 nm, without shield representatives: the poliowirus, virus Coxsackie, the rinovirusy, virus of hepatitis of types A called out diseases: poliomyelitis, inflammation heart muscle, common colds, jaundice infectious

• Togaviridae profile: ssRNA (+), having shield, ikosaedralny nucleocapsid representatives: the virus of German measles, arbovirus the called out diseases: German measles, yellow fever

• Rhabdoviridae profile: the ssRNA (-), the shape of bullet, having the shield the representatives: the virus of madness the called out diseases: madness

• Retroviridae profile: ssRNA, having shield and ikosaedralny kapsyd, tranksryptazę use in process of contagion opposite to producing copy the genoms of DNA representatives: the human virus of leukaemia of lymphocyte T type 1 (HTLV -1), the human virus of acquired shortage of resistance ( the HIV) the called out diseases: the leukaemia of matur cells T, the team of acquired shortage of resistance (AIDS)

PROFILE of CHOSEN the VIRUSES

Bacterial viruses

Bacterial viruses' huge number exists (bacteriophages) many of them has compiled structure, only some possess proteins areola. Studied viruses' majority attacks E. coli or Salmonella typhimurium.

Bacteriophages RNA

The best got to know bacteriophages RN - those contain 1 RNA. At Enterobacteriaceae the bacteriophages infect only the cell playing the part of givers in process the genetic recombination connected which is from occurrence on these cells specific it urges on, being simultaneously the receptors for particles these viruses. Bacteriophages these, they are small (ok. 26 nm) and ikosahedron' have symmetry. These bacteriophages' some genomy became already got to know np. MS2 RNA has about length genom 3569 nucleotides, thread (+), which it acts as mRNA directly. In host's cell mRNA comes in to ribosome and four types of proteins be produced: the maturity, responsible for decomposition, structural to building of overcoat as well as "replikaza" the RNA (combination of the virus and farmer's polypeptides). Is curiosity, that gene proteins responsible it for lizę of farmer's cell intrudes both on gene proteins coat how and on gene "replikazy", what in result causes that beginning translation of this genu is no kids as long as rise suitable quantity proteins coat.

Ikosahedron' bacteriophages ssDNA

Bacteriophages ssDNA have in form of closed wheel about diameter genome 25 nm, overcoat built from individual white in 60 copies different proteins creator structure to which be added. Bacteriophages these, in contrast to previous, they during duplication use from cellular machinery mainly and possess in own the genome only basic information relating the whites capsid'.

Bacteriophages dsDNA

Many viruses contain in figure of double thread of DNA the genetic material. Open bacterial viruses were this first and they are very intensely studied. The the largest and the most compiled phag both under in relation to structure how and phages T belong to of group duplication - even. Example - phag from this group is T4, having ikosahedrom' elongated through additional whites head as well as diverse structurally stalk. In genome T4 is atypical nucleotide 5 - hydroxymetylocytozine instead of cytosine which causes that it is the data of DNA resistant on restrictive bacterial "endonukleazy". DNA T4 steps out in linear form however his genetic map be represented in circular form. Gene phag T4 code two basic groups of proteins; early, that is the engaged in process of "replikacji" and transcription enzymes, as well as the late that is the proteins the structural heads and the stalk, and also the enzymes freeing phag from cell. Phag T4 uses in track of synthesis with polymerase RNA stepping out in bacterial cell. Forming head and stalk sets independently, DNA becomes packed up in head then it attaches stalk and phag finished it is to abandonment of cell. Destruction of the cellular bacterium's wall sets under influence of lysozyme which attacks cellular peptydoglikany. Whole process can last about 25 minutes.

Gentle viruses

The bacterial viruses' majority crosses lytic cycle the leader to destruction of bacterial cell. Yet many viruses are, which in spite possibility of destruction of cell choose road of lysozyme that is gentle when then majority gene phag does not undergo expression and gene built-in to bacterial it undergoes synchronic duplication and with cellular fissions be passed on bacterium's next generations together with. Infected in gentle figure the virus bacteria is resistant on next attacks of new particles this virus necessarily. Gentle viruses usually exist in cells in called with provirus form. Provirus possesses the same genetic information how virus. However she is blocked by special phags' repressor and it does not undergo expression. This situation can undergo the change under influence of specific factors (example: radiation X, UV) causing repressor's inactivation. Gentle virus can exist in two dependent forms from conditions. The time as independent individual, controlling one's duplication ( lytic cycle), or as DNA the integrate in genetic material of the host's cell ( gentle cycle).

Pic. 4 - Cycle life phag lytic.

Pic. 5 - Cycle life lyzogenic phag.

Animal viruses

Animal viruses possess genetic material both in form RNA how and DNA. Retrovirus are one of animal viruses' more important groups, because they cause very dangerous diseases for man (AIDS). It divides on different groups the viruses in dependence from type of nucleic acid, the presence of areola and sometimes according to applied model the "replikacyjnego". The virus infection of animal cell can have corner effects. Virus can cause destroy cell, durable infection from slow freeing particles virus or infection potential when then symptoms they appear from considerable delay in relation to time of infection. Moreover viruses can cause formation tumours.

Viruses animal RNA (+)

They to this viruses' group belong: the virus of polio, hepatitis A, the cold viruses. In small viruses RNA of such how the polio, the RNA acts as individual mRNA using from translational cellular machinery directly poliproteine produces individual long which it becomes cut up on numerous small indispensable whites in process the duplication the nucleic acid then ( the polymerase RNA) as well as rise of new the virus' particle (ex. the proteins structural). The synthesis of cellular whites becomes inhibited.

Viruses animal RNA (-)

In these viruses RNA does not play part mRNA directly. It is first copied by RNA - the dependent polymerase the RNA of virus origin what the mRNA comes into being used then to synthesis of virus proteins which lead to duplication genom' virus and rise virus' new particles. The human virus of influenza is example of virus of this type, moreover rhabdoviruses.

Viruses animal dsDNA

It among viruses DN those - were it been possible was to distinguish four main families; papovaviruses, viruses herpes, pox and adenoviruses. From among them all beyond viruses pox cross in cellular nucleus duplication, however pox was duplicated in cytoplasm. Some viruses from group papovaviruses have ability to inducing neoplasmic transformation of host's cells. When virus of this type infects cell, they can drop in two types of duplication in dependence from cell. In cells first type virus' infection depends on creating new virions and destroy of host's cell. It in second type of cells does not come to multiple duplicating virion', but virus DNA integrates in genomie some cells leading to genetic modification, which it in consequence can cause the transformation cell and lack of set - back of her growth. Possessing ability to inducing in animal cells tumours SV40 is such virus' example. Viruses herpes are large group viruses' dsDNA causing many diseases with animals and man (ex. windy smallpox) they some, have ability to staying in potential in host's cells form can lead to neoplasmic transformation (ex. virus Epstein - Barr). The most compiled and the largest animal viruses pox belong to viruses' group. The ability is these viruses' unique propriety to carrying out on terrain of cytoplasm of cell host the duplication of DNA. It it virus to this group was one should was was smallpox, which as first became examined in detail, as well as vaccine's virus (cowpox), which it causes in human cells very gentle and not dangerous infection. Vaccine's virus serves as vaccine against true smallpox as well as be used in genetic experiments to introducing to animal cells strange genes and human. The adenoviruses became after once first isolated from tonsils, they cause the gentle infections of respiratory roads and they step out in healthy persons often.

Retroviruses

One from the most compiled and animal viruses' the most doubtless interesting groups retrovirus are. Causes they for which are in centre of interest many is. After first, then they became identified as inducing factors formation tumours initially. After second, one of retrovirus is cause one from the most the most dangerous and the most controversial in a modern manner diseases that is AIDS. Moreover they can integrate in genom of host's cell by indirect form what is here DNA. Introducing to cells strange genes in genetic therapy process this be studied under angle. Beyond this retrovirus possess enzyme - opposite "transkryptaze" which applying RNA as matrix copies information genetic from RNA on DNA. Enzyme this is applied in genetic engineering universally. It it was one should was here mark that opposite "transkryptaza" is not "tool" reserved for retrovirus exclusively - possess her also "retrotranspozon" at Eukaryota or E. coli. Retrovirus possess about ultra symmetry areola. There are retrovirus' Genom very atypical building. It consists he from two equal individual threads RNA (+) , joint with hydrogen bonds across evaporation from specific particles nucleotides tRNA. Process of the retrovirus' duplication sets in several stages generally. On beginning virus gets to cell, one of thread RNA is inversely transcribed in ssDNA which then it becomes transformed in linear dsDNA by opposite "transkryptazę". It is the next stage formed the integrate the retrovirus' dsDNA in genom of the host's cell. The transcription of virus DNA sets then, mRNA comes into being and "descendant" virus RNA which becomes packed up in capsid on terrain of cytoplasm. In end virus' new particles be cut off from cytoplasmic integument and freed from cell. Transcription RNA is after virus' entry first stage to cell on DNA near use opposite "transkryptazy". Enzyme this shows several genera of activity; the synthesis of DNA from utilization the RNA as matrix ( the opposite "transkryptaza"), the synthesis of DNA from utilization of DNA as matrix ( the DNA polymerase) as well as the degrading in hybrid the thread RNA RNA - the DNA. How all the DNA polymerase enzyme this requires to synthesis of DNA primeru. In reaction carried out by opposite transcriptase primerem is specific cellular tRNA. Used genus tRNA he be connected with virus' type. In aim copying remaining majority RNA different mechanism be applied. Copied already by RT RNA be removed first (reverse transcriptase) thanks her activity "rybonukleazowej" which causes the leaving the small of section of "jednonicioweg"o DNA end RNA. This section of DNA be transferred on second side of thread RNA and hybridize from 3" end and then finished the synthesis of DNA becomes(-) on matrix RNA. The working RT as "rybonukleazy" leads to removal the RNA with except of small of fragment which becomes used as primer to synthesis of positive thread of DNA. Created dsDNA becomes from LTR at last (long terminal repeats) on both ends. LTR contain the strong promotory of transcription and take part in process of integration which can drop in in any point of cellular DNA. Integrate virus' fragment be called with provirus and becomes with stable genetic element. The provirus' of DNA be transcribed by cellular the RNA becomes in RNA which the polymerase the equipped the tail poly(A) and the cap the goat, and it can then be packed up in virus' particle or it can undergo in proteins translation virus.

Vocabulary:

Written by: Agatha Doodek Dudek (Polish text)