microbiology reading 2 .pdf

Chapter 5 Intro - Although bacteria and viruses account for a large number of infectious disease that affect humans, many serious illness are caused from eukaryotic organisms - One examples is Malaria which is caused by plasmodium, a eukaryotic organism transmitt...

Chapter 5 Intro - Although bacteria and viruses account for a large number of infectious disease that affect humans, many serious illness are caused from eukaryotic organisms - One examples is Malaria which is caused by plasmodium, a eukaryotic organism transmitted through mosquito bites - This is a major illness and threatened 3.4 billion people worldwide - Organ failure and blood or metabolic abnormalities contributes to medical energies and sometimes death And relapses may occur - In countries where malaria is endemic, the disease represent a more public health challenge, that can place a tremendous trains on developing economies - Efforts to stop this disease include distribution of insecticide treated bed nets and the spraying of pesticide - Researchers are also working on creating a vaccine that are effective - In late 2021 R21/matrix M became the first vaccine to be recommended for widespread use by the world health organization and at least 10 other candidate vaccines are in development this is a multinational Involvements working with governments, universities nonprofits and pharmaceutical companies - The Malaria Research and Training center in mali has done the most research and they have critical clinical trial 6.1 - Despite their small size there was a discovery of a filterable component smaller than a bacteria that causes tobacco mosaic disease, that dates back to 1892 - At the time Dmitir Ivonvski discovered the source of TMD by using a porcleicle filtering devices first invented by charles chamberlain and Louis Pasteur , these have a pore size of 0.1 um, which is small enough to move all bacteria less than 02 from any liquids passed through the device - An extract obtained from TMD infected tobacco plants was made to determine the cause of the disease, initially it was thought to be bacterial. - Ivanvoski using the filter found that the cause of TMJ was not removed after passing the extract through the poricling filter - Therefore is a bacteria was not the cause of TMD what could be cueing the disease, he concluded must be an extremely small bacterium or bacterial spore - Other scientists continued looking into thai  - It was Beijerinck in 1899 who concluded that is was not a bacteria but instead possibly a chemical, like poison or what we would describe today as a toxin - As a result the word Virus- Latin for poison was used to describe the cause of TMD- a few years after his initial discovery - Even though he was not able to see the virus that caused TMD and did not realize the cause the cause was not a bacterial, he is credited as the original discovery of Viruses and founder of the field of virology - Today we see virus using an electron microscope - Viruses are distinct biology entities, however there is not a lot known about their evolution - In terms of taxonomy they are not included in the tree of life as they are Acellular - In order to survive and reproduce viruses must infect a cellular host, making them Obligate intracellular parasites - The genome of a virus enters a host cell and direct the production of the viral components, Proteins and Nucleic Acids needed to form new Virus particles called Virions - New virions are made in the host cell by assembly of Viral components, these new virions transport the viral genome to another host cell to carry out another round of infection Hosts and Viral transmission - Viruses can infect every types of host cell, Including those of plants, animals, fungi, protists, bacteria and Archaea - Most viruses will only be able to infect the cells of one or a few species of an organism- this is called the host ranged - However having a wide host range is not common and viruses will typically only infect specific hosts and only specific cell types within those hosts - The viruses that infect bacteria are called Bacteriophages, or simply phases - the word phase comes from the greek word for devour - Other viruses are just identified by their host ground, such as animal or plant viruses - Once a cell is infected, the effects of the virus can vary depending on the type of virus - Viruses may cause abnormal growth of the cell or cell death, alter the cell's genome or cause little noticeable effect in the cell - Viruses can be transmitted through direct contact, indirect contact with fomites, or through a vector - which is an animal that transmits a pathogen from one host to another  - Arthropods such a mosquitos, ticks and flies are typical vectors for viral diseases, and they may act as mechanical vectors or biology vectors - Mechanical transmission occurs when the arthropod carrier a viral pathogen on the outside of its body and transmits it to a new host by physical contact - Biological transmission occurs when the arthropod carrier the viral pathogen inside of its body and transmits it to the new host through biting - In humans a wide variety of viruses are capable of causing various infection and disease - Some of the deadliest emerging pathogen in humans are viruses, yet we have few treatments or drugs to deal with viral infections, making them difficult to eradicate - Viruses that can be transmitted from an animal host to a human host can cause zoonoses - For examples the avian influenza virus originates in bird but can cause disease in humans - Reverse zoonosis are caused by infection of an animal by a virus that originated in a human Viral Structure: - In general Vernons are small and can't be observed using a regular light microscope - They are much smaller than prokaryotic and eukaryotic cells, this an an adaption allowing viruses to infect these larger cells - The size of a virion can range from 20 nm for small viruses up to 90090 for typical large circles - Recent discoveries however have identified new giant viral species such as panoavirus salinus and Pithovirusi sibicum with sizes approaching that of a bacterial cell - After the development of the electron Microscope, Wendall Stanly was the first scientist to crystallize the structure of the tobacco mosaic virus and discovered that is is composed of RNA and Protein - In 1943 he isolated Influenza B vistus which contributed to the development if ab Influenza vaccine - This discovery unlocked the nature viruses that had been puzzling sciences for over 40 years and was awarded the nobel prize in 1946 - Because of research we now know that viruses consist of a Nuclieic acid- Either RNA or DNA surrounded by a protein coat called a capsid- the interior is not filled  with cytosol, as in a cell but contains the bare necessities in terms of genome and enzymes needed to direct synthesis of new virions Each capsid is composed of proteins subunit called Capsomeres made of one or more different types of capsomere proteins that interlock to form the closely packed capside - There are 2 categories of viruses based on general composition, Viruses formed from only a Nucliec acid and Capsid are called naked viruses or nonenveloped viruses - Viruses formed with a Nucleic acid packed capside surrounded by a lipids Layer are called enveloped viruses with a nucleic acid packaged capsid, - The viral envelope may either be intracellular or cytoplasmic in origin - Extending outward and away from the capsid of some naked viruses and enveloped virus are protein structure called spikes - At the topics of these spikes are structures that allow the virus to attach and enter a cell, like the Influenza viruses spikes that allow the virus detach from the cell surface during release of new VirensInfluenza viruses are often identified by their H&M Spike Spike's for example each one and and one influenza viruses are responsible for the pandemics in 1918 in 2009 H2 n two for the pandemic in 1957 H three n 2 for the pandemic in 1968 - Viruses vary in the shape of their capsids which can be either helical polyhedral or complex a helical capsid forms the shape of tobacco mosaic virus and naked here cofire us and a bola virus an envelope Tellico virusThe caps it is cylindrical or rod shaped with the genome fitting just inside the length of the capsid polyhedral capsids from the shapes of poly viruses and rhinoviruses and consist of nucleic acid surrounded by a polyhedral many sided capsid in the form of an icosahedron. - A icosahedral capsid is a 3-D at three dimensional 20 sided structure with 12 vertices; these caps somewhat resemble a soccer ball; both helical and polyhedral viruses can have envelopes. - King on viruses can have envelopes Viral shapes seen in certain types of bacteriophages such as T4 Fage And poxvirus is like Vikina virus may have features of both polyhedral and helical viruses so they are described as complex viral shape. - In the bacterial phage complex form the genome is located within the polyhedral head and the sheath connects head to the tail fibers and tell pens that help the virus attached to receptors on the host cell's surface. - Poxviruses that have complex shapes are often brick shaped with intricate surface characteristics not seen in other categories of the capsid. Classification and Taxonomy of virus  - Other viruses are not classified in the three domains of life their numbers are great enough to require classificationSince 1971 the international union of microbiological societies virology division has given the task for developing refining and maintaining a universal virus taxonomy to the international committee onTaxonomy of viruses - Since viruses commuted so quickly it can be difficult to classify them into genus and species apathy using the bio Romeo name and culture system since the ICTV is viral nomenclature system classifies viruses into familiesAnd Genera based on the viral genetics chemistry morphology and mechanism of her multiplication - Today at the ICTV has classified no one viruses and seven orders 96 families and 350 Ginera bio families names end in Viridae Ingenious names and with virusThe names of viral orders family and Genera are all italicize when referring to a viral species we often use a genus and species epithet Such asPanda virus door sis - The Baltimore classification system is an alternative to ICTV nomenclature the Baltimore system classifies viruses according to their genomes a.k.a.DNA or RNA a single versus double stranded and motive replication this system plus create seven groups of viruses that have common genetics and biology - Aside from formal systems of nomenclature of viruses are often informally grouped into categories based on chemistry morphology and other characteristics they share in common categories may include naked or envelope structures single-stranded or double stranded DNA or RNAGenomesSegmented or unsegmented Gino's and positive strand or negative strand RNA - For example herpes viruses can be classified as Diaz DNAEnvelope virus human immunodeficiency virusIs a single-stranded RNA enveloped virus and Tobacco mosaic virus is a single-stranded RNA virusOther characteristics such as host specificity tissue specificity caps size and shape and special jeans and enzymes may also be used to describe groups of similar viruses Classification of Viral Diseases - What are the ICTV has been tasked with biological classification of viruses it has also played in important role in the classification of disease caused by viruses - Distillate take the tracking a virus of the related human diseases that I see TV has created classifications that link to the international classification of diseases  the standard taxonomy of disease that is maintained an updated by the world health organization - The ICD assigns an alphanumeric code of up to six characters to every type of viral infection as well as all other types of diseases medical conditions and causes of death - This ICD code is used in conjunction With two other coding systemsThe current procedural terminologies in the healthcare common procedure coding system to categorize patient conditions for treatment and insurance reimbursement - For example when a patient six treatment for a viral infection ICD codes are routinely used by clinicians to order laboratory test and prescribe treatments specific to the virus specific acted of causing the illness - Does ICD code is then used by medical laboratories to identify test and must be performed to confirm the diagnosis ICD code is used by the healthcare management system to verify that all treatment in laboratory work performed are appropriate for the given virus - Medical coders use ICD codesTo assign the proper code of for procedures performed and medical billers intern use this information to process claims for reimbursement by insurance companies Vital record keepers use ICD code to record cause of death on death certificates and epidemiologists use ICD codes to calculate morbidity and mortality statistics 6.2 - All viruses depend on sells for reproduction and metabolic processes by themselves viruses do not in code for all the enzymes necessary for viral replication but within a wholesale of Irish can commander cellular machinery to produce the viral particles - Bacteriophages replicate only in the cytoplasm since prokaryotic cells do not have a nucleus or organelles in eukaryotic cells most DNA viruses can replicate inside the nucleus with an exception observed in the large DNA viruses such as pox virus is that can replicate in the cytoplasm with a few exceptions RNA viruses that infect animal cells replicate in the cytoplasmImportant exception will be highlighted layer is the influenza virus The Life Cycles of Viruses with Prokaryotes Hosts - The life cycle of bacteriophages have been a good model for understanding out viruses affect the cells that they infect - Send similar processes have been is Herb for eukaryotic viruses which can cause immediate death of the cell or establish a latent chronic infection Byerland phages typically lead to the death of the cell through so lysis temperate phage is on the other hand can become a host chromosome and they are replicated with the cell genome until such time as they are inducing to make newly assembled viruses Or progeny viruses The Lytic Cycle: - During the light to cycle of violence phage the bacteriophage takes over the cell reproduces new faces and destroys the cell TVand phage is a good example of a well characterize class of Ireland phages - There are five stages in the bacteriophage liked excel cycleAttachment is the first stage in the infection process in which the phase interact with specific bacterial surface receptors most pages have a narrow host range and may in fact one species of bacteria or stream within a species this unique recognition can be exploited for targeted treatment of bacterial infection by faze therapy or fish typing to identify unique bacterial subspecies are strange - The second stage of infection is entry or penetration there's a curse the contraction of the tail she's which accent like a hypodermic needle to inject a viral genome through the cell wall and membrane the fish head and remaining components remain outside the bacteria - The third stage of infection is biosynthesis of a new viral component after entering the host of the virus synthesizes virus in coded and don't nucleus is to grade the bacterial chromosomeThen hijacks the hotel to replicate transcribe and translate the necessary viral componentsCasemiro's, she is, base plates, tail fibresAnd viral enzymes for the assembly of new viruses polymerase jeans are usually expressed early in the in the cycle Well capsid and tail proteins are expressed later during the mature Asian Fage new Virens are created - To liberate free phages the bacterial cell wall is disrupted by face proteins such as Hollyn or laces on the final stages released  mature viruses burst out of the host cell in a process called license and the parking viruses are liberated into the environment to infect new cells Lysogenic Cycle: - In a lysogenic cycle the phage genome also enter the souther attachment and penetration a prime example of a phase with this type of lifecycle is the land of age during the lights of Genex psycho instead of killing the house the phase genome integrate into the bacterial chromosome and becomes part of the hostIntegrated face genome is called a prophage a bacterial house with a prophage is often called a Lysogen - The process in which bacterium is infected by a temperate phage It's called a life so Jenny it is typical of temperate phage is to be latent or inactive within the cell - As the bacterium replicates and it's chromosome it also replicates the phages DNA in passed it onto new daughter cells during reproduction the presence of the fish may alter the phenotype of the bacterium to take care bring extra jeansThis change in the hose phenotype is called lysogenic conversion or face conversion some bacteria such as Video chlorateAre less violent in the absence of the prophage the phases infecting these bacteria carry the toxin jeans and their genome and enhance their Virgins of the host when they toxic jeans are expressed in the case of the Cloria phage encoded toxin can becauseSevere diarrhea - During Leiser jenny the prophage will persistIn the host, Jean until induction which results in thatExcision of viral genome from the host comazon After induction has occurred the temperate phage can proceed through electric cycle and then undergo lysogenyIn a newly infected cell Transduction: - Transduction occurs when a bacteriophage transfers bacterial DNA From one bacterium to another during sequential infections there are two types of transduction generalized and specialized - During the late text cycle of viral replication the virus hijacked the hotel degrades the hose chromosome and makes more viral genomeIs it assembled in packages DNA into the fish head packing can occasionally makes a mistake instead of packaging viral DNA it takes a random piece of host DNA and inserted into the capsid once released is Byron will then inject the former host DNA into a newly  infected hostThe asexual transfer of genetic information can allow for DNA recombination to occur that's providing the new house with NewJeans - Generalized transaction occurs when a random piece of bacterial chromosome DNA is transferred by phage during the light to cycle - Specialized transaction occurs at the end of the lights of Jenny cycle where the pro fish is exercise and the bacteriophage enters the light to cycle since the features integrated into the host gene on the prophage can replicate as part of the host have a some conditions e.g.Ultraviolet light exposure or chemical exposure stimulate The prophage to undergo induction causing the phage to exercise from the genome Intergalactic cycle and produce new phages to leave host cells - During the process of excursion from the host comazone a phase me occasionally remove some bacterial DNA near the site of viral integration the Faigin host DNA from one end or both ends of the integration site are packed within the capsid and her transferred to the new infected hostSince the DNA transferred by the phages not randomly package but instead of specific piece of DNA near the side of integration this mechanism of gene transfer is referred to as specialized transactionThe DNA can recombine with host, zones giving the ladder new characteristics transduction seems to play an important role in the evolution airy process of bacteria giving them a mechanism for asexual exchange of genetic information Life Cycle of Viruses with Animal Hosts - Like took animal viruses follow similar infection stages to bacteriophages attachment penetration biosynthesis metrician and release however the mechanisms of penetration nucleic acid biosynthesis and release difference between bacterial and animal viruses - After binding to host receptors animal viruses enter through endocytosis engulfment by the host cell or through membrane fusion Biro envelope with the host cell membrane - Many viruses are host specific meaning they only infected certain type of host and most viruses only infect certain types of cells within tissuesThis specific tea is called A tissue tropism examples of this our demonstrated by the polio virus which exhibit tropism for the tissues of the brain and spinal cord or the influenza virus which has a primary tropisms for the respiratory tract - Animal viruses do not always expressed their jeans using the normal flow of genetic information DNA to RNA to protein some viruses have a dsDNA genome like cellular organisms and can follow the normal flow however others may have single-stranded DNA double stranded RNA are single-stranded RNA genomes  the nature of the genome determines how the genome is replicated and expressed as viral proteinsIf a genome is single-stranded DNA host enzymes will be used to synthesize a second strand that is complementary to the genome strand that's producing double stranded DNA itThe double trying to DNA Kanell be replicated transcribed and translated similar to the host DNA - If the viral genome is RNA a different mechanism must be used their three types of RNA genomeDouble-stranded RNA a positive single-stranded RNA or negativeStranded RNAIf a virus has a single-stranded RNA genome it can be translated directly to make a viral proteins viral genomic Single-stranded RNA acts like a cellular mRNA however if it virus contains negative single-stranded RNA Gino the hose ribosomes cannot translate it until negative single-stranded RNA is replicated into positive single-stranded RNABuy viral are in a dependent RNA polymerase (rDRP). - They are DRP is also important enzyme for the replication of double-stranded RNA viruses because it uses the negative strand of the double stranded genomeAs a template to create positive single-stranded RNA at the newly synthesize positive single-stranded RNA a copies can they be translated by cellular ribosomes - A different mechanisms for viral nucleic acid the synthesis is observed in the retroviruses which are positive single-stranded RNA viruses single-stranded RNA viruses such as HIV carry a special enzyme called refersTranscriptaseWithin the cab said that synthesizes a complementary single strand of DNA (cDNA) Copy using the positive single-stranded RNA genome as a template the single-stranded DNA is then made into double stranded DNA in which can integrate into the host chromosome and become a permanent part of the host the integrated viral genome is called a provirus the virus cannot remain in the host for a long time to establish the chronic infectionThe provirus stage is similar to the prophase stage in bacterial infection during the lysogenic cycle have unlike prophage the provirus does not undergo excision after splicing into the genome Persistent Infections: - Persistent infection occurs when a virus is not completely cleared from the system of the host but stays in certain tissues or organs of the infected person - The virus may remain silent or undergo productive infection without seriously harming are killing the host - Mechanism of persistent infection may involve the regulation of the viral or host gene expression or the alteration of the host immune response the two primary categories of persistent infections are latent infection and chronic infection  - Examples of viruses that cause latent infections include herpes simplex virus Varicella zoster SpirosI ie chickenpox and shingles And Epstein-Barr virus isHepatitis A virus and HIV or two examples of viruses that cause long-term chronic infections Latent Infection: - Not all animal viruses undergo replication by the like dick cycle there are viruses that are capable Remaining hidden are doorman inside the cell in a process called latency these types of viruses are known as Layton viruses and make us late an infection viruses capable of latency Manish leave causing acute infection before becoming dormant - For example the Vasila zoster virus infects many cells throughout the body and causes chickenpox characterized by Arash of blisters covering the skin about 10 to 12 today's post infection disease resolved in the virus goes dormant living within the nerve cell ganglia for yearsDuring this time the virus does not kill the nerve or continue replicating it is not clear why the virus stops replicating within the nerve cells and expresses few viral proteinsAnd some cases typically after many years of dormancy the virus is reactivated and causes a new disease cause shingles rash chickenpox affects many areas throughout the body shingles is a nerve cells specific disease emerging from the ganglia in which the virus was dormant - Leighton viruses may remain dormant by existing as cellular viral genome molecules outside of the house chromosomeOthers become proviruses by integrating into the host gene them during dormancy viruses do not cause any symptoms of disease and may be difficult to detect a patient may be unaware that they are carrying the virus unless a viral diagnostic test has been performed Chronic Infection: - A chronic infection is a disease with symptoms that are recurrent or persistent over a long time some viral infections can be chronic if the body is unable to eliminate the virus HIV is an example of a virus that produces a chronic infectionOften after a long period of latency - What is a person becomes infected with HIV the virus can be detected in tissues continuously there after but untreated patients often experience no symptoms for years - However the virus maintains chronic persistence There's several mechanisms that interfere with immune function including preventing expression of viral antigens on the surface of infected cellsDuring immune cells themselves  restricting expression of viral jeans and rapidly changing viral antigens through mutationEventually the damage to the immune system results in progression of the disease leading to acquired immunodeficiency syndrome (Aids) - The various mechanisms that HIV uses to avoid being cleared by the immune system are also used by other chronically infecting viruses including Hep c Life Cycle of Viruses with Plant Hosts: - Plant viruses are more similar to animal viruses than they are to bacteriophages - Plant viruses maybe envelope or non-envelope - Like many animal viruses plant viruses can have either a DNA or RNA Gino and be single-stranded or double stranded have your most plant viruses do not have a DNA genome the majority have a positive single-stranded RNA genome which acts like messenger RNAOnly a minority of plant viruses have other types of genomes - Plant viruses have a narrow a broad host range for example the citrus Tristeza virus infects only a few plants of the citrus genusWhere is the cucumber mosaic virus infects thousands of plants of various plan families most plant viruses are transmitted by contact between plans or by phone gay nematodes in sex or other arthropods that act as mechanical vectorsOur some viruses can only be transferred by a specific type of insect factor for example upper Taylor virus might be transmitted by aphids but not white flies in some cases viruses may also enter healthy plans through wounds which Has Occurred due to pruning or whether damage - Viruses that infects plants are considered bio trophic parasites which means they can establish an infection without killing the host similar to what is observed in the later genic life cycles of bacteriophages - Final infection can be asymptomatic (Or latent) or can lead to the death Of the cell Which is called lytic infection - The life cycle begins with the penetration of the virus into the house so next to viruses uncoated within the cytoplasm of the cell when the caps it is removed depending on the type of nucleic acid cellular components are used to replicate the viral genome and synthesized by the proteins for assembly of new ByronzTo establish a systemic infection the virus must enter part of the vascular system of the plant such as the flow on the timer cleared for a systematic infection may vary from a few days to a few weeks depending on the virus the plant species and the environmental condition the virus life cycle is complete toilet is transmitted from an infected plan to healthy plant  Viral Growth Curve: - I like the growth curve for a bacterial population growth curve for a virus population overage lifecycle does not follow a sigmoid he'll curve during the initial stage and inoculum virus causes infectionIn the eclipse faceViruses bind in penetrateThe cells with no Virus detected in the medium the chief difference that appears next is the viral growth curve compared to a bacterial growth curves occurs when Virens are released from the lysed Host cell at the same time such an occurrence is called a burst And the number of irons per bacterium released is described as the burst size - In a one step multiplication curve for bacteriophage the host cells lies releasing many viral particles to the medium which leads to a very steep prize in viral TeeterWhich is the number of Virens per unit volume if no viable host cells remain the viral particles begin to degrade during the decline of the culture 6.3 Isolation of viruses: - I like bacteria many of which can be growing on an artificial nutrient medium viruses require a living host cell for replication - Infected host Cells Eukaryotic or prokaryotic can be cultured and growingAnd then the growth medium can be harvested as a source of virus - Virens in the liquid medium can be separated from the host cells by either centrifuge Asian or filtration filters can physically remove anything present in the solution that is larger than Byronz the viruses can be collected in the filtrate Cultivation of Viruses: - Viruses can be grown in vivoWhich is within a whole living organism plant or animal or invite trough which is outside a living organism and sell or artificial environment - Flat Horizontal Cell culture flask are a comment vessel used for invite your work bacteriophages can be grown in the presence of a dense layer of bacteria Also called a bacterial lawn Groenen is 0.7% soft agree in a petri dish or flat horizontal flask Is the bacteria many plaques are observed among the cloudy bacteria lawn - Animal viruses require cells within a host animal or tissue culture cells derive from an animal - Animal viruses cultivation is important for identification and diagnosis of pathogenic viruses in clinical specimens production of vaccines and basic research studies - In vivo host sources can be a developing embryo in an embrocated bird egg Or a whole animal for example most of the influenza vaccine manufactured for annual flu vaccination program is cultured and hens eggs - The embryo or host animal serves as an incubator for the viral replication location withinThe embryo or host animal is important many viruses have a tissue tropism and must therefore be introduced into a specific site for growth within an embryo target sites include amniotic cavity The chorioallantoic membrane or the yolk sac viral infection may damage tissue membranes producing listens called pox disrupt the embryonic development or caused the death of the embryo - Foreign Vitro studies various types of cells can be used to support the growth of viruses a primary cell culture is freshly prepared from animal organs or tissues cells are extracted from tissues by mechanical scraping or mincing to release cells by an enzymatic method using trypsin or collagenase to break up tissue and release single cells into suspension - Because of anchorage dependence requirements primary cell cultures require a liquid culture medium in a petri dish or tissue culture flask so cells have a solid surface such as glass or plastic for attachment and growth - Primary cultures usually have a limited lifespan when cells in a primary culture undergo mitosis and a significant density of cells produce sells come in contact with other cells when they sell to sell contact occurs mitosis is trigger to stop - This is called contact inhibition and it prevents the density of cells from becoming too high to present contact inhibition cells from the primary cell culture must be transferred to another vessel with Fresh growth medium - This is called a secondary cell culture periodically sell density must be reduced by pouring off some cells and adding fresh medium to provide space and nutrients to maintain cell growthIn contrast the primary cell culture is continuous cell line Usually derive from transform selves or tumors are often able to be subculture many times or even grow indefinitely In which case they're called immortal  - Continuous cell lines may not exhibit anchorage dependence they were growing suspension and may have lost their contacting her Bishop as a result continuous and lions can grow in piles are lumps resembling small tumor grows - An example of immortal cell line is the Gila cell line which was originally cultivated from tumor cells obtained from Henrietta lacks a patient who died of cervical cancer in 1951 - Helo cells were the first continuous tissue culture cell line and were used to establish tissue culture as an important technology for Resurgeons cell biology biology and medicine prior to the discovery of HeLa cells scientist were not able to establish Tissue culture is with any reliability or stability - More than six decades later this cell line is still alive and being used for medical research Detection of a virus: - Regardless of the method of cultivation once a virus has been introduced into a whole host organism embryo or tissue culture cellSample can be prepared from the infected host embryo or cell line for further analysis under Bright Field electron are fluorescent microscope - Cytopathic events CPEsAre distinct observatories sell abnormalities do the viral infection CPEs can include loss of adherence to the surface of the container changes in cell shape from flat to round shrinkage of the nucleus vacuoles in the cytoplasm fusion of the cytoplasmic membrane and the formation of multi nucleated sin Catia Inclusion bodies in the nucleus or cytoplasm and complete cell lysis - Further pathological changes include viral disruption of the host you know and I'll trade normal cells into transform cells which are the types of cells associate with carcinomas and sacramentsThe type or severity of the CPE depends on the type of virus involved Hemagglutination Assay: spelling- read textbook - Hey serological assay is used to detect the presence of certain types of viruses in patient serum serum is the straw colored liquidFraction of blood plasma from which clotting factors have been removed serum can be used in a detect I say called hemaGalatian I say to detect specific types of viruses in the patient sample  - How maculation is the accusation clumping together of your 30 TetasWhich is also known as red blood cells many viruses produce surface proteins are spy called Gemma glad she winsThat can bind to receptors on the membranes of earth reciters and Cassels to Aguila in itI'm at the light is the endIs observable without using a microscope but as a method that does not always differentiate between infectious and non-infection is viral particles since both canUgly as shit eight Anthro sites - To identify specific pathogen genetic virus using this method we must use an indirect approach proteins called antibodies generated by the patient immune system to fight a specific virus can be used to barn components such as how many Galatians that are uniquely associated with specific types of viruses - The binding of the antibodies with the Gemma Galatians found on the virus subsequently prevent or throw sites from directly interacting with the virus so when earth roses can be added to the antibody Covid viruses there's no appearance of acclamationI can initiate has been inhibited we call these types of indirect essays for virus specific antibodiesMacGlashan inhibition assays - HAI can be used to detect the presence of antibodies specific to many types of viruses that may be causing her have caused infection in a patientBeen months or years after infection this is as described in greater detail Later Nucleic Acid Amp test - Nucleic acid amplification testOr NAAT Are used to molecular biology to detect unique nucleic sequences of viruses in patient samples - Polymers change reactions PCR is an NAAT used to detect the presence of viral DNA in a patient's tissue or body fluids sample PCR is a technique that amplifiesI eat synthesizes many copies of a viral DNA segment of interest using PCR short nucleotide sequence is called primaries can buy to specific sequences of viral DNA enabling identification of the virus - Reverse transcriptase PCR is an NAT used to detect the presence of RNA viruses are TPC our differences from PCRIn that the enzyme reverse transcriptase is used to make a cDNA from the small amount of viral RNA in the specimen the CTABe amplified by PCR both PCR and RTPCRAre used to detect and confirm the presence of the viral nucleic acid impatient specimens Enzyme Immunoassay  - Amazon amino acids rely on the ability of antibodies to detect an attached a specific biomolecules called antigens - Detecting antibody attaches to the target antigen with a high degree of specifically in what might be a complex mixture of biomolecules also include in this type of essay is the colorless enzyme attached to the detecting antibodyThen say Max has a tag to the on the detecting antibody and can interact with a colorless substrateLeading to the production of a coloured and product yeah I is often rely on layers of antibodies to capture and react with antigens all of which are attached to a membrane filterEIS her viral antigens are often used as preliminary screening test if the results are positive for the confirmation will require test with even greater sensitivity such as a western blot or NAAT 6.4 Viroids: - In 1971 Theodore diner on pathologist working at the agricultural research service discovered in a cellular particle that he named viroid for meaning virus like - Viroids consistOnly a short strand of circular are in a capable of self replication the first Virus discovered was found to cause potato tubers spindle disease which causes slower sprouting and various deformities in potato plants - Like viruses potatoes spindle Tuber viroid PS TVs take control of the host machinery to replicate there are any GinoViruses viroids do not have a protein coat to protect their genetic information - Viroids can result in devastating losses of commercially important agricultural food crops grown in fields in Orchards - Since the discovery of PS TV other viroids have been discovered that causes diseases in plants - Tomato plant immaculate viroid infects tomatoes plants which causes loss of chlorophyll disfigured and brittle leaves and very small tomatoes resulting in laws of productivity in this field crop avocado sunblock viroid result in lower years of poor quality fruitThis is a smallest by Roy discovered that far that infects plants peach latent mosaic viroid can cause Necrosis of flower buds And branches and wounding of ripened fruit Which leads to fungal and bacterial growth in the fruit PLMV can also cause similar pathological changes in plums nectarines apricots and cherries resulting in decreased productivity in these orchards as well  - Viroids in general can be dispersed mechanically during crop maintenance or harvesting vegetative reproductionAnd possibly via season in sex resulting in severe drop in food availability and devastating economic consequences. Virusoids: - A second type of pathogenic RNA that can infect commercially important agricultural crops are the virus which are some viral particles best described as non-self replicating single-stranded RNA - RNA replication of Irish way to similar to that of viroids but I'd like viroids virucides require the cell to also be infected with a specific helper virus - There are currently only five describe types of viruses And their associated helper viruses the helper viruses are all from the family of sober mom viruses an example of a helper virus is the subTerranean clover model virus which is an associated viricide package inside the viral capsuleWants to help her virus enters the host cell the virus rides are release and can be found free in plant cells cytoplasm where they possess ribosome activity that help or virus undergoes typical viral replication independent of the activity of the viricide the virus or genomes are small only 220 to 388 nucleotides long Viricide genome does not code for any proteins but instead serves only to replicate viroid RNA - Prioritize belong to a larger group of infectious agent called satellite RNAs which are similar pathogenic RNAs found in animals unlike plant fireside satellite RNAs mean code for proteinsLike plansSatellite RNAs may coin fact with a helper virus to replicate one satellite RNA that infects humansAnd that has been described by some scientist as a virus side in the hepatitis delta virus which buy some sort is also called hepatitis delta virus side much larger than a plant viricide HTV has a circular single-stranded RNA genome of 1000 and 700 nucleotidesAnd can direct biosynthesis of HDV associated proteins the HDB help her virus is the hepatitis B virus infection with HPV and HDV result in more severe is pathological changes in the liver during infection which is how HTV was first discovered Prions: - At one time scientist believe that any infection is particle mass contain DNA or RNA and then a 1982 Stanley person or a medical doctor studying scrappy a fatal degenerative disease and sheep discovered that the disease was caused by  proteinaceous infection is particles or prionsBecause proteins are a cellular and do not contain DNA RNA prisoners finding were originally met with resistance in skepticism fiber his research was eventually validated and he received the nobel prize in physiology or medicineIn 1997 - A prion is a miss folded rogue form of normal protein found in the cell this rug prion protein which may be caused by a genetic mutation or occur spontaneously can be infection stimulating other Endo generousNormal proteins to become miss folded forming plaques - Today prions are known to cause various forms of transmissible spongiform encephalopathy (TSE) - In humans and animals TSE Is a rare degenerative disorder that affects the brain and nervous system the accumulation of rock protein causes the brain tissue to become sponge like killing brain cells informing holes in the tissue leading to brain damage lots of motor coordination and dementia infected individuals are mentally impaired and become an able to move her speak there's no cure in the disease progresses rapidly eventually leading to deathWithin a few months or years - TSC in humans include Carell fatal familial insomniaGerstmann Stachler sky Schnur disease - TSC and animals include male cow disease scrappy which is in sheep's and gold and chronic wasting disease which is an elk and deer TSA can be transmitted between animals and from animals to humans by eating contaminated meat or animal feedTransmission between humans can occur through hereditaryOr buy contact with contaminated tissueAs might occur during blood transfusion or organ transplant there's no evidence for transmission via casual contact with an infected person.