Flashcards on Viruses PDF

Creating Your Flashcards... How do viruses differ Viruses are not alive, so from other microbes? they can't be killed, and What are the main Capsid: a protein layer that structures of a virus? protects the genome. Envelope: a lipid bilayer derived from the host cell that surrounds some instead, are...

Creating Your Flashcards... How do viruses differ Viruses are not alive, so from other microbes? they can't be killed, and What are the main Capsid: a protein layer that structures of a virus? protects the genome. Envelope: a lipid bilayer derived from the host cell that surrounds some instead, are inactivated or viruses. Genome: the neutralized. They cannot nucleic acid that encodes replicate on their own, but the instructions to create rather, they assemble from new viral particles. individual components. How many families of 16 families of RNA viruses viruses are human and 8 families of DNA pathogens contained viruses. What is a virion? A single, infective, complete, and mature viral particle that can deliver the viral genome and lead within? to a productive infection in an appropriate host cell. What are some Viruses are metabolically differences between inert, while bacteria can viruses and bacteria? make energy and encoded proteins. Viruses require living cells to replicate, while bacteria can divide on their own. What is a bacteriophage? A type of virus that infects bacteria and may be important in the acquisition of virulence factors and antibiotic resistance phenotypes among bacteria, and can also be used to treat hexagons, similar to a infections. soccer ball. What are the three main Spherical, icosahedral, and viral shapes? filamentous (helical). Definition of Virus A complex infectious agent, typically consisting of a nucleic acid genome wrapped in a protein coat, that is able to replicate What is symmetry in A way to classify viral only within the living cells terms of viral capsids? capsid shapes, with of a host. common ones being helical, icosahedral, or complex (when one of the What is an icosahedron? other terms doesn't apply). Components of Viruses Genome and Capsid. A shape made of 20 Genome The complete set of triangles arranged into genetic material of an pentagons and 12 vertices, organism, usually for example, a 20-sided contained in DNA or RNA. die. Several small viruses have this symmetry, but many larger ones contain arrangements of both 5 and 6 triangles to form both pentagons and Types of Viral Genomes DNA or RNA, single- or Types of Capsids double-stranded, linear, Icosahedral, filamentous, matrix, or enveloped. circular, or segmented or polyploid. Structure of an Envelope A membrane derived from the host cell that contains Structure of Capsid Made up of many copies of viral proteins and one or several proteins, glycoproteins. which self-assemble onto the nucleic acid genome (forming a nucleoprotein complex called the Importance of Envelope Impacts how the virus nucleocapsid) or into a replicates, transmits and distinct structure that infects, and can also surrounds it. determine its susceptibility to external stresses. Functions of Capsid Package and protect the nucleic acid genome and Structural Characteristics Spike glycoproteins and essential proteins, and aid of Enveloped Viruses fusion proteins found in the in the delivery of nucleic envelope, which help with acid to the host cell for viral attachment and entry infection. into host cells. parts of the body or in Acquisition of Envelope external environments. During the virus budding process through a lipid raft section of a host cell membrane. Viral Stability The ability of a virus to What is the relatively Multi-output regressions quick means for a focus on using algorithms conformal non-linear to estimate functions that diffyq to solve? relate multiple output variables to an input and withstand environmental past state variables in stresses such as heat, order to predict future drying, solvents, or acidity, output behavior. which may differ based on its structure. Susceptibility of They are often more Enveloped Viruses to susceptible to heat, drying, External Stresses mild solvents, and acidity Which type of viruses Naked viruses survive typically survive for longer on inanimate longer in the external objects and are environment? transmitted more insidiously, while enveloped due to their lipid bilayer. viruses will not reach the intestine due to acid sensitivity. Importance of Virus The structure can Structure for Inactivation significantly limit the effectiveness of disinfectants on different Which type of viruses are Enveloped viruses, as they more likely to be survive poorly in the transmitted via direct external environment, host-to-host contact or often need to move based on genetics and inhalation? quickly between hosts. shared characteristics. What is the primary Naked viruses, which are What does the suffix - A classification as a viral cause of viral diarrhea? almost always responsible viridae signify in a viral family, such as Retroviridae for diarrhea due to their family name? or Paramyxoviridae. What is the term for the DNA or RNA, which can be stability in the intestine. What types of viruses are Enveloped viruses, as they nucleic acid that makes linear or circular in more easily inactivated have a lipid envelope that up a viral genome? structure. by detergents and mild is easily broken down. What are the three main Linear, circular, or arrangements for viral segmented (in pieces). disinfectants? What is the main The envelope allows for advantage of having an more surface proteins, envelope for a virus? giving the virus a better genomes? ability to infect and replicate. What types of symmetry Helical (tubular or can viral capsids have? helicoidal) or icosahedral (spherical). What is the purpose of To simplify the learning grouping viruses into process by categorizing families? What is the significance Enveloped viruses have a What type of molecule is of an envelope for a lipid membrane that is found in an enveloped virus? derived from the host cell, virus, but not a naked providing additional virus? Lipid protection and allowing for better replication. What information can be The type of nucleic acid, gleaned from a viral genome structure, and replication flowchart? envelope presence of a virus. What is the main function To protect and contain the of the viral capsid? viral genome. What is the key The presence or absence difference between of an envelope, enveloped and naked respectively. viruses? Which families of viruses Red families refers to the are essential to know for families that contain this module? viruses that cause diseases and must be learned for What is meant by viral Viral tropism refers to the this module. tropism? ability of a virus to replicate in specific types of host cells, tissues, and organs. What is the main role of a To protect and contain the viral capsid? viral genome, as well as attach to host cell What are the six steps of The six steps of the viral receptors for infection. the viral replication replication cycle are cycle? attachment, penetration, uncoating, synthetic phase, assembly, and release. What are the seven steps The seven steps of the viral of the viral replication replication cycle are cycle? attachment, penetration, uncoating, replication, What is the eclipse period The eclipse period is the of a virus? time between when a virus assembly, release, and maturation. enters a host cell and when the first progeny are assembled. What determines host Host range and specificity range and specificity in are determined by cell viruses? susceptibility and What is the primary The primary target of an target of an effective effective neutralizing neutralizing antibody? antibody is the membrane glycoprotein of an enveloped virion. permissiveness for the virus. How do viruses enter Viruses enter host cells by host cells? binding to their cognate receptors on the cell How do viruses Viruses reproduce within a reproduce within a host host cell by using the host cell? cell's machinery and surface and may then be internalized. building blocks to make copies of the viral genome and proteins. What are the two types The two types of viruses of viruses in terms of are those with DNA genetic material? genomes and those with RNA genomes. What are the three types The three types of DNA of DNA viral families? viral families are double- What is the primary way Viruses primarily replicate that viruses replicate within host cells by using within host cells? the host cell's machinery and building blocks to produce more copies of their genome and proteins. stranded (dsDNA), gapped (Gapped DNA), and singlestranded (ssDNA). Name three RNA viral Three RNA viral families are families. Picornaviruses, How do some viruses Some viruses modify the modify host cells to aid in function of host cells to their own replication? make them better suited for producing viral progeny. Togaviruses, and Flaviviruses. What is the difference An enveloped virus has a between an enveloped host-derived membrane and naked virus? lipid surrounding its nucleic In what way do viruses Viruses differ from bacteria differ from bacteria and and eukaryotes in that they eukaryotes in terms of do not divide to reproduce; reproduction? instead, they disassemble and use host cell acid and proteins, while a machinery to produce new naked virus has no viral particles. surrounding membrane. What determines which Virus cell susceptibility and cells/tissues/organisms host cell permissiveness will be affected by a an infectious lytic viral virus? particle in a culture medium. How does a virus attach to a host cell? Viral attachment proteins bind to cell surface What are the general 1. Attachment (adhesion, receptors or co-receptors. stages of viral adsorption, or binding), 2. replication? Entry What is the difference Susceptibility refers to the between host cell presence of surface What is the first step in Attachment of the virion to susceptibility and host receptors for viral the viral replicative cycle? the host cell. cell permissiveness? attachment, while How does a virus initially Through electrostatic bind to a cell receptor? forces, followed by other permissiveness refers to the ability of the cell to support viral replication. short-range forces. Define the latent period The time between viral of a viral infection. entry and new progeny release, which can range What is the difference Attachment refers to the from hours to years. between viral attachment binding of the virion to the and viral adhesion? cell, while adhesion refers to the binding of the viral attachment proteins to the What is a plaque-forming A way to visualize and unit (pfu)? measure the presence of cell surface receptors. What is the role of viral To bind to cell surface How do naked viruses Through membrane attachment proteins receptors or co-receptors penetrate the host cell? puncture, where the viral (VAPs)? for viral attachment. nucleic acid is inserted into the cytosol through a pore created by the virus. How does viral Through endocytosis, penetration into the host membrane fusion, or a cell occur? combination of the two. Perforation The transfer of a complete virion through the cell membrane without causing significant What is the role of To block viral penetration neutralizing antibodies in into host cells. damage. viral entry? Lysis A mechanism for viral particles to escape from an Which type of viruses use Naked viruses. endosomal compartment an endocytic pathway for by rupturing it. entry? Fusion The combination of the What is the importance It is important for viral envelope and the cell of the pH in the uncoating of the virus. membrane of the host cell endosomes? to penetrate and infect the cell. Endocytosis The process of enveloped Low pH A common event during viruses entering cells viral entry that triggers through fusion with the changes in viral protein endosomal membrane. structure to promote capsid uncoating. Direct Fusion Enveloped viruses entering cells directly through Viral Spikes Viropexis Transport System Processes that move fusion between viral viruses within cells, using envelope proteins and the either actin filaments or host cell's membrane. microtubules. Proteins on the surface of Uncoating The progressive, stepwise the virus that bind to process of destabilizing receptors on host cells, the viral capsid to release promoting fusion and the replication-competent penetration. form of the viral genome. A method of entry for Genome The nucleic acid in either a naked capsid viruses where RNA or DNA virus that viral spikes bind to contains the genetic receptors on host cells. instructions for replication and host cell infection. transport system of the Nuclear Pore Complex cell for the movement of The site for entry of viruses parts for assembly. that target the nucleus, using nuclear import receptors and specific signals. What do we mean by Packaging is when viral packaging? genetic material is incorporated into the Karyopherins capsid, but is limited by the Proteins that facilitate size of the capsid. entry into the nucleus, allowing viruses to infect non-dividing, terminally differentiated cells. What is envelopment? Envelopment is when enveloped viruses acquire an external membrane Cell Division layer, derived from a host The replication step that organelle or the plasma includes genome membrane. duplication, gene transcription, protein translation, and posttranscriptional events. What is viral assembly? Viral assembly can occur in different cellular compartments and relies on the cytoplasmic What is the difference During sequential between sequential and assembly, the capsid and simultaneous assembly? envelope are assembled one after the other and often in different locations. During simultaneous assembly, the structural proteins attach to the to virus production, genome as it is synthesized although some enveloped and the virus may acquire viruses may induce latency an envelope as it buds and have no immediate through a membrane. effect on the cell. Unique trait of all viruses The inability to live What is the process of Viral particles must move viral release? from one cell to another independently without and can do so via cell lysis, having a host; they cannot exocytosis, or budding. synthesize their own DNA, RNA, or proteins What is the difference Naked viruses are usually between naked and released by cell lysis and To maintain themselves, Infect host cells, and these enveloped virus release? are more likely to cause cell viruses must host cells then process the damage. Enveloped viruses viral nucleic acids, may be released by ultimately permitting the exocytosis or budding, virus to proliferate and which leaves the host cell infect new host cells. intact. What happens to cells in These cells will likely die which enveloped viruses due to inflammation and are replicating? damage caused by resources being diverted Antiviral medications Mechanisms of cell entry take advantage of and virus proliferation to control infection. proliferation of other The typical course of viral Is self-resolving with a infection healthy host mounting immune cells. innate and adaptive immunity responses. Major histocompatibility Present viral antigens to complex (MHC) class I cytotoxic (CD8+) T molecules lymphocytes to induce a cell-mediated immune Hummoral response to The production of viral infection involves antibodies to free the virus. Cytotoxic response to The destruction of viral infection involves infected cells. response. Primary role of natural To trigger an innate killer (NK) cells immune response in Issues that can arise in Unchecked viral immunocompromised proliferation leading to patients organ dysfunction and even death due to the response to a lack of MHC absence of mechanisms to class I molecules on clear the infection. infected cells. Interferon α Secreted by infected and immune cells, helps combat viral infection by halting protein synthesis in uninfected cells and upregulating the Primary aim of antiviral To prevent the virus from medications completing its metabolic process for self-replication. Palivizumab A humanized monoclonal Nucleic Acid Replication The process of copying antibody that targets one strand of DNA into respiratory syncytial virus another strand of DNA. (RSV) to prevent fusion to the host cell membrane. Transcription The process by which RNA polymerase makes a Amantadine A medication used to treat working copy of DNA code influenza A by inhibiting from a gene (or specific set the viral membrane protein of instructions) to mRNA, in required for uncoating. order for the ribosome machinery attached to the mRNA to read and translate the code for the Side effects of Nausea, anorexia, creation of a specific amantadine nervousness, insomnia, protein in the cell. seizures, and livedo reticularis (reddish-blue mottling of the skin). Nucleic Acid Synthesis Drug classes that inhibit Inhibitors the synthesis of DNA and RNA in viruses, each with a Additional potential use Treatment of Parkinson's unique mechanism for for amantadine Disease. blocking this pathway. Guanosine Analogs Acyclovir Drugs that mimic the Ganciclovir A purine analog with a structure of nucleosides similar mechanism of and can block the action to acyclovir, used lengthening of DNA primarily for prophylaxis strands, reducing viral and treatment of CMV and proliferation. administered intravenously. A purine analog that needs Viral DNA Polymerase A class of antivirals that to be converted to Inhibitors block viral DNA nucleoside triphosphate polymerase by mimicking for its activity, acting as a nucleotides, including substrate and inhibitor of Foscarnet which acts as a viral DNA-polymerase. noncompetitive inhibitor of many viral RNA and DNA polymerases and can also work against HIV reverse Resistance Up to 50% of HSV strains transcriptase. may be resistant to acyclovir due to a lack of thymidine kinase; other resistance mechanisms Ribavirin A nucleoside analog that include modified DNA mimics adenosine or polymerase or a tyrosine guanosine and is used to kinase with reduced treat chronic hepatitis C activity. infection, severe respiratory syncytial virus infection, and other DNA and RNA viruses; has adverse effects such as anemia, bone marrow suppression, and teratogenicity. Translation of Viral The process of using the Proteins genetic instructions encoded in the viral RNA to produce proteins that are necessary for the virus to replicate and spread. Interferon-α A cytokine produced in response to viral infection or cancer, used as a medication to treat hepatitis B and C; has signaling effects that halt protein synthesis in uninfected cells and help mount an immune response.