Term
| What is a virus? Definition. Major characteristics. Are viruses living or nonliving entities? |
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Definition
| Viruses are small (nm) agents that are able to propagate only in living cells. They infect all forms of life. |
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Term
| How can viruses be visualized? |
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Definition
| Either by electron microscope or by observing their effect on living cells. |
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Term
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Definition
| A discrete visible zone in a layer of host cells, one plaque is the progeny of one virus. |
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Term
| What are the important viral structures? |
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Definition
| Genome (DNA or RNA), capsid, envelope. |
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Term
| What types of genome may viruses have, and how do they mutate? |
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Definition
| dsDNA, ssDNA, ssDNA circular, dsDNA circular - also the same with RNA except that RNA doesn't form ssRNA circular. |
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Term
| What is recombination via reassortment? |
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Definition
| If a genome has several strands of DNA or RNA they may interchange with that of another virus when two viruses infect the same cell. |
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Term
| What are three typical virus shapes? |
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Definition
| Icosahedral, helical, and complex. |
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Term
| What is the genome of influenza? |
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Definition
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Term
| What are some of the genome termini modifications in viruses and what do they do? |
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Definition
| Extra proteins added, CAP, polyA tail, and other secondary structures. These protect the genome from degrading, facilitate genome copying and expression. |
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Term
| What are examples of viral proteins? |
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Definition
| Capsid, envelope, tegument, matrix, enzymes. |
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Term
| How are viruses classified? |
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Definition
- By name of the region where the virus was isolated
- By the nature of the pathological effect
- By the name of the host
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Term
| What is the mainstream method of viral classification today? |
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Definition
| The Baltimore classification, which groups viruses by the type of nucleic acids they possess, and its replication scheme. |
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Term
| What are the seven groups of the Baltimore classification? |
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Definition
- dsDNA
- ssDNA
- dsRNA
- +ssRNA
- -ssRNA
- RNA reverse transcribing viruses
- DNA transcribing viruses
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Term
| What is the lytic cycle of viruses? |
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Definition
| Adsorption, Penetration, Biosynthesis, Assembly, Release |
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Term
| How does the lysogenic life cycle differ from the lytic cycle? |
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Definition
| It has a step involving viral genome integration. |
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Term
| What are the major vaccine types? |
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Definition
| Attenuated, inactivated, and recombinant. |
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Term
| What is an inactivated vaccine? |
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Definition
| Whole agents which are fragments of the virus (Gardasil etc.), unable to replicate in vaccinated individual. Retains immunogenicity of infectious agent. |
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Term
| What are attenuated vaccines? |
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Definition
| Weakened form of pathogen generally unable to cause disease, strain replicates in vaccine recipient causing mild or undetectable symptoms, long lasting immunity. |
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Term
| What are recombinant vaccines? |
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Definition
| Genetic engineering is used to recombinate DNA. The vaccine can be recombinant proteins, viruses or bacteria, or the DNA itself. |
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Term
| What are the stages of the virus entering the cell, in simple terms? |
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Definition
Viral attachment : receptor binding
Viral entry: breaking the barrier of the
cell membrane
Uncoating: releasing the naked viral
genome at the correct place in the cell
Transport |
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Term
| What are the nonspecific defenses of the body? |
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Definition
- Inflammation
- Fever
- Phagocytosis
- Complement
- Interferons
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Term
| What is the purpose of inflammation? |
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Definition
| To limit damage and restore function, because release of toxic products and enzymes from phagocytic cells is responsible for tissue damage. |
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Term
| What is the purpose of fever? |
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Definition
| Inhibits growth of pathogen by elevating temperature above maximum growth temperature, activates and speeding up other body defenses. |
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Term
| What is complement and what are its outcomes? |
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Definition
| Composed of 20 proteins, which split into a and b fragments after activation, leads to inflammation and also causes lysis of virus infected cells as well as drilling holes in virus envelope. |
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Term
| What are strategies that viruses use to compensate for small genome size? |
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Definition
- IRES - internal ribosomal entry site
- alternative reading frames
- translational readthrough
- polycistronic RNAs
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Term
How do viruses become compatible with cellular transcription / translation machinery??? What can they do other than becoming compatible? |
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Definition
- CAP/PolyA mRNAs (CAP snatching)
- - IRES
- - Compatibility with the cell transport and
modification systems
Compete with cellular moleules, RNAs, etc.
- - Strong transcription promoters
- More robust enzymes
- Destruction of cellular molecules
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Term
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Definition
| ANTIbody GENerators. Compounds that induce an immune response, proteins and saccharides induce a strong response, i.e. viral envelope and capsid. Lipids and nucleic acids do not induce a strong response. |
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Term
| What are the classes of antibodies, and which are important? |
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Definition
| IgM, A, and G are most common, D and E also exist. |
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Term
| What is the most common antibody? |
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Definition
| IgG, a monomer, 80% of serum immunoglobin, found all the time, even in placenta blood. Also, binds to Fc receptors of phagocytes. |
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Term
| What are the other 2 important antibodies? |
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Definition
| IgA, a dimer is the second most common, high in secretions. IgM is the least common, a pentamer, appear after immunization or exposure to a pathogen. |
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Term
| Describe the primary immune response. |
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Definition
| The first time the body is exposed to an antigen, IgM is the first antibody, IgG builds up gradually. Slow, steady reponse, not extremely effective. |
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Term
| Describe the secondary immune response. |
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Definition
| Fast, effective, efficient. IgM is still the first antibody, but IgG is rapidly produced due to memory B cells becoming activated. |
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Term
| What are some major drug targets for HIV? |
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Definition
| Reverse transcriptase nucleoside and nucleotide analogs, integrase, protease, and entry inhibitors. |
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Term
| What are the two types of entry for a virus? |
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Definition
| Receptor mediated fusion and endocytosis. |
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Term
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Definition
| A single (+) RNA in a capsid, affects motor and bulbar neurons, typically doesn't cause symptoms, but can. |
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Term
| What is the small pox virus? |
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Definition
| Single dsDNA with hairpin loops at the end, uniquely replicates in the cytoplasm instead of the nucleus. Variola virus, pox type virus. Nearly extinct in all countries except third world. |
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Term
| What are the major characteristics of Herpes? |
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Definition
| dsDNA segment, heparin sulfate is the main receptor, propogates in rapidly dividing cells such as skin cells, dormant in nerve cells, nucleoside analogs used as drug targets, chain terminators. |
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Term
| What are the major characteristics of HIV? |
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Definition
| Two copies of ssDNA, permissive cells are Th cells with CD4+, causes AIDS in the long term due to destruction of human immune system. |
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Term
| What is the main difference between nucleoside/tide inhibitors for herpes and those for HIV? |
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Definition
| For Herpes the saccharide is altered such that it lacks an -OH group, in HIV the base is altered to have different functional groups. |
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Term
| Does HIV require any cellular enzyme to replicate its DNA? |
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Definition
| No, reverse transcriptase carries out all needed functions, including destruction of the DNA/RNA intermediate. |
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Term
| Where does reverse transcription occur for retroviruses? |
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Definition
| In the host cell's cytoplasm, before the genome is integrated into the host DNA. |
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Term
| What enzyme is needed for the release of HIV virions from the cell? |
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Definition
| Protease at the cell membrane. |
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Term
| What are the phases of clinical trials? |
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Definition
- Preclinical trials - test tube & animals
- Phase I - 20-80 subject
- Phase II - 20-300 subjects
- Phase III - 300-300 subject, multicenter trials
- AVAILABLE ON MARKET
- Phase IV - long term effects, interaction, protection are quantified
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Term
| What types of clinical trials are there? |
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Definition
- Randomized - study subjects randomly assigned to receive treatment or placebo
- Blind - subjects dont know what they're getting
- Double Blind - neither the subject nor researchers know whats being given.
- Placebo controlled - use of a placebo to measure the effect of a drug
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Term
| What are some theories of HIV's emergence? |
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Definition
| THe house cat theory, hunter (chimp) theory, conspiracy theory. |
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Term
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Definition
| over 100 subtypes, dsDNA virus, naked, requires actively dividing cells to propogate, similar to herpes virus but doesn't reside in neurons. Causes warts. Can cause cancer by integrating into the human genome. |
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Term
| What processes do B cells go through after coming in contact with an antigen? |
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Definition
| Affinity maturation and clonal selection. |
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Term
| How long does it take to antibodies to be detected in the bloodstream during primary immune response? |
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Definition
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Term
| What are the stages of lymphocyte development? |
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Definition
- Naive - have antigen receptor but haven't encountered antigen
- Activated - able to proliferate, have bound antigen
- Effectors - descendants of activated lymphocytes, produce specific cytokines and enhance immune response, plasma cells
- Memory lymphocytes - long lived descendants of activated lymphocytes
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Term
| What are the general characteristics of T lymphocytes? |
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Definition
| Never produce antibodies, do not react with free antigen must be presented by APC. |
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Term
| What are cytotoxic T cells? |
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Definition
- Proliferate and differentiate to destroy infected or cancerous self
- have CD8 marker
- generate memory cells
- different from NK cells
- recognize MHC I
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Term
| What are the helper T cells? |
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Definition
- Multiply and develop into cells that activate B cells and macrophages
- Stimulate other T cells, orchestrate immune reponse
- Have CD4 marker
- generate memory cells
- HIV viral target
- recognize MHC II
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Term
| What is humoral versus cellular immunity? |
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Definition
| Humoral eliminates extracellular pathogens, cellular eliminates intracellular pathogens. |
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