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186 Cards in this Set
- Front
- Back
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Acellular
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Nonceullular, not made up of cells.
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Virus
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Minuscule, acellular, infectious agent usually having one or several pieces of nucleic acid - either DNA or RNA.
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Genome
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The sum of all genetic material in a cell or virus.
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What does vaccine mean in Latin?
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Poison.
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Ivanowsky
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Viruses are smaller than cells; can pass through filters. First demonstrates that viruses are acellular.
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Stanley
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Isolated and characterized tobacco mosaic model.
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Virion
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A virus outside of the cell, consisting of proteinacious capsid surrounding a nucleic acid core. Completely assembled infective virus.
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Envelope. Why is it needed?
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Phospholipid membrane surrounding the viral capsid. Needed for infectivity.
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Capsid
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A protein coat surrounding the nucleic acid core of a virion.
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OIP
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Obligate intercellular parasite. Must be within a cell to reproduce.
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What were viruses first called?
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Filterable agent.
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Nucleocapsid
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The nucleic acid and its capsid.
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Inert
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Inactive outside of host cell.
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Capsomere
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A proteinacious subunit of a capsid. Individual protein molecules.
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Outermost layer of a virion.
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Capsid or envelope.
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What does the outermost layer of a virion provide the virus?
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Provides protection and recognition sites that bind to complementary chemicals on the surfaces of their specific host cells.
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What happens once a virus is inside?
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Intracellular state is initiated and capsid is removed.
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What is found within the capsid?
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The core, where genetic material is found.
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How many strands of genetic material can a virus have?
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Single or double stranded.
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Shape of genetic material.
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Linear or circular.
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Peplomer
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Some viruses have these spikes. Used for binding.
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Bacteriophage
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A virus that infects bacteria. Aka phage.
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Specificity
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Based on tissue or cell infected.
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3 basic types of virus shapes.
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Helical, polyhedral, and complex.
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Enzymes found in core of virus.
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RNA polymerase, DNA polymerase, and neuraminidase.
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Virus particle
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Virus with unknown infectivity.
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Helical
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Rodlike
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Helical
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Rodlike
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Complex shape
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Combination
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Polyhedral
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20 sided icosahedral.
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Criteria for viral classification.
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1. Symptoms
2. Nucleic acid 3. Enveloped or naked 4. Specificity |
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Megavirus
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500 nm in diameter.
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Typical size of viruses.
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10-200 nm.
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Criteria of life.
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1. Grow, respire, and carry out metabolic activities.
2. Reproduce 3. DNA or RNA 4. Respond to environment 5. Mutates: spontaneous, recombination 6. Transduction |
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Enveloped virion
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A virus with a membrane.
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Enveloped virion
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A virus with a membrane.
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Naked virion
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Virion without an envelope.
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How does a virus acquire its envelope?
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From its host cell during viral replication or release.
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What happens to the host cell of a virus after replication?
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Death and lysis.
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Lytic replication
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Process of viral replication consisting of five stages ending with lysis of and release of new virions from host cell.
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Five stages of lytic replication.
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1. Attachment: of virion to host cell.
2. Entry: of the virion into its genome into the host cell. 3. Synthesis: of new nucleic acids and viral proteins by the host cell's enzymes and ribosomes. 4. Assembly: of new virions within the host cell. 5. Release: of the new virions from the host cell. |
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Lytic replication of bacteriophages.
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1. Attachment
2. Entry 3/4. Synthesis 5. Assembly 6. Release |
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Attachment: Lytic rep. of bacteriophage.
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Dependent on chemical attraction and precise fit between attachment proteins on tail fibers and complementary receptor proteins on cell wall. Very specific.
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Entry: Lytic rep. of bacteriophage
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Release lysozyme so genetic material can be injected. Once inside, viral enzymes break down material DNA, alter, and makes genetic material for new cells.
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Lysozyme
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A protein maybe carried within the capsid that weakens the peptidoglycan of the cell wall.
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Synthesis: Lytic rep. of bacteriophage
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Degradation of bacterial DNA. Bacterium stops synthesizing own molecules and is under control of virus. Requires host cell to replicate genome, transcribe (RNA) and translate (DNA) genomes.
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Assembly: Lytic rep. of bacteriophage
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Capsomeres spontaneously attach to one another to form new capsid heads. Tails assemble and attach to heads and tail fibers attach to tails forming mature virions. Transduction.
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Release: Lytic rep. of bacteriophage
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Newly assembled virions are released from the cell as lysozyme completes its work in cell wall. Bacteria gets lysed.
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All bacteriophages are ___ viruses.
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DNA
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Shape of all bacteriophages.
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Complex
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Lysogeny
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Process of viral replication in which bacteriophage enters a bacterial cell, inserts into the DNA of host, and remains inactive. Phage is then replicated every time the host cell replicates its chromosome. Later, phage may leave.
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Lysogenic phage
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Bacteriophage that doesn't immediately kill its host cell. Aka temperate phage.
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Plaques
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Disintegrating bacterial cells in a lawn look as if lawn is being eaten, appearance of these plaques that prompted name of bacteriophage.
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Burst time
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Period of time required to complete entire lytic process.
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Burst size
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Number of new virions released from each lysed bacterial cell.
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Process of lysogeny. Steps 1-3.
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1. Viral DNA enters cell, but DNA not destroyed. Virus remains inactive. Aka prophage.
2. Prophage remains inactive by coding for a protein that suppresses prophage genes. Prophage is inserted into DNA of the bacterium, becoming physical part of chromosome. 3. Fusing pieces of DNA. every time the cell replicates its infected chromosome, prophage is also replicated. |
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Process of lysogeny. 5-8.
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5.
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Process of lysogeny. 4-8.
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4. All daughter cells are infected with virus. Can change phenotype of bacterium. Bacteriophage genes are responsible for toxins and other disease-evoking proteins. Can leave chromosome. Cell division.
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Process of lysogeny. 4-8.
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4. All daughter cells are infected with virus. Can change phenotype of bacterium. Bacteriophage genes are responsible for toxins and other disease-evoking proteins. Can leave chromosome. Cell division.
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Process of lysogeny. Step 4.
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4. All daughter cells are infected with virus. Can change phenotype of bacterium. Bacteriophage genes are responsible for toxins and other disease-evoking proteins. Can leave chromosome. Cell division.
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Lysogeny steps 5-8.
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5. Inductive agents are typically the same physical and chemical agents that damage DNA molecules.
6. Synthesis 7. Assembly 8. Release |
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Prophage
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Inactive bacteriophage.
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Lysogenic conversion
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Harmful to pathogenic in lysogeny.
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Induction
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Process whereby a prophage is excised from the host chromosome.
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Attachment of animal viruses.
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Same as bacteriophage: dependent on on chemical attraction and exact fit between proteins or glycoproteins.
Difference: Animal viruses lack both tails and tail fibers. Instead, have spikes or other attachments. |
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Entry and uncoating of animal viruses.
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Animal viruses enter shortly after attachment. 3 types of entry: direct penetration, membrane fusion, and endocytosis.
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Direct penetration and example.
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Process by which the viral capsid attached and sinks into cytoplasmic membrane, creating a pore through which genome enters the cell. Ex: Polio virus.
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Membrane fusion
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Entire capsid, including genome, entrees host. Viral envelope and host cell membrane fuse, releasing the capsid into the cell's cytoplasm and leaving the envelope glycoproteins as part of cell membrane.
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Membrane fusion
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Entire capsid, including genome, entrees host. Viral envelope and host cell membrane fuse, releasing the capsid into the cell's cytoplasm and leaving the envelope glycoproteins as part of cell membrane.
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Endocytosis
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Attachment of virus to receptor molecules on cell's surface stimulates the cell to endocytize the entire virus.
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Membrane fusion
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Entire capsid, including genome, enters host. Viral envelope and host cell membrane fuse, releasing the capsid into the cell's cytoplasm and leaving the envelope glycoproteins as part of cell membrane.
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Endocytosis
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Attachment of virus to receptor molecules on cell's surface stimulates the cell to endocytize the entire virus.
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Uncoating
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Removal of viral capsid within a host cell.
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Synthesis of DNA viruses of animals.
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Each type of animal virus requires a different strategy for synthesis, depends on what kind of nucleic acid is involved. DNA viruses typically enter the nucleus and most RNA viruses are replicated in the cytoplasm.
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dsDNA synthesis
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When the virus invades, it enters nucleus where cellular enzymes replicate genome. Host cell reads DNA and replicates it. RNA is transcribed and capsomere proteins are made in cytoplasm. Then, capsomeres enter nucleus and spontaneous replication occurs.
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Example of dsDNA and two exceptions.
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Ex: herpes and HPV.
Exceptions: smallpox stays in the cytoplasm and hep B makes RNA that's used as template. |
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Example of dsDNA and two exceptions.
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Ex: herpes and HPV.
Exceptions: smallpox stays in the cytoplasm and hep B makes RNA that's used as template. |
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Reverse transcriptase
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Transcription into RNA which is then used as template to make DNA copies.
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ssDNA synthesis
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Parvovirus. When it enters nucleus, host enzymes produce a new strand of DNA complementary to the viral genome. It then binds to ssDNA of virus and forms dsDNA molecule.
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Replication
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Replicate genome.
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Replication
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Replicate genome.
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Transcription
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RNA from DNA.
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Translation
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Making protein from RNA.
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Positive ssRNA synthesis and ex.
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Ex: Polio. Genome in all. Acts just like mRNA. Goes directly into ribosome and is translated into protein. If being replicated, must make -ssRNA which is used as template for replication.
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Positive retrovirus and example
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Ex: HIV Gets into host. Becomes template to make DNA that is transcribed from +RNA by reverse transcriptase carries within capsid. Once made, used to make more RNA. RNA used for transcription and translation.
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-ssRNA synthesis
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RNA gets into host cell. Makes complementary copy of it. Takes the special enzymes RNA dependent RNA transcriptase which is released into cytoplasm during uncoating and transcribed +RNA molecules from -RNA genome.
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dsRNA Synthesis
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Positive strand serves as mRNA for translation of proteins; RNA polymerase transcribed dsRNA. Each strand of RNA acts as template for transcription of its opposite.
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Assembly and release of animal viruses
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Most DNA viruses assemble in and released from nucleus into cytosol. RNA viruses develop solely in cytoplasm. Enveloped viruses are released via budding: slowly. Allows host cell to live longer. Cloaks self with part of membrane as it leaves.
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Assembly and release of animal viruses
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Most DNA viruses assemble in and released from nucleus into cytosol. RNA viruses develop solely in cytoplasm. Enveloped viruses are released via budding: slowly. Allows host cell to live longer. Cloaks self with part of membrane as it leaves.
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What happens if the cell isn't quickly lysed?
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Allows infected cell to remain alive for some time. Become persistent infections.
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How are naked animal viruses released?
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Exocytosis or cause lysis of cell.
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Latency
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the phase in certain viruses' life cycles in which, after initial infection, proliferation of virus particles ceases. However, the viral genome is not fully eradicated.
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Latency
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When a virus remains dormant in cell.
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Latency
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When a virus remains dormant in cell.
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Provirus
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Viruses involved in latency.
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Antiviral chemicals
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Interferons and antibodies.
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Cancer
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Disease characterized by presence of one or more malignant tumors.
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Neoplasia
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Uncontrolled cell division in multicellular animal.
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Benign
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Remain in one place, localized, and aren't generally harmful.
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Malignant
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Invades neighboring tissues and travels systemically to produce new tumors.
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Metastasis
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When new tumors are made and it invades systemically.
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Metastasis
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When new tumors are made and it invades systemically.
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Protooncogenes
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Genes that play role in cell division.
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Oncogene
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Activated genes of cancer.
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Oncogene
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Activated genes of cancer.
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Carcinogens
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Cancer causing chemicals like UV light and gamma radiation.
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% of viruses that cause cancer.
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20-25.
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Viral cancer
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Some viruses carry copies of oncogenes as part of genome. Others promote oncogenes already present in host. Others interfere with normal tumor repression when they insert into repressor genes.
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Culturing a virus
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Must be cultured in a living cell. Phages in bacteria. Very specific. Enbryonated chicken eggs are often used. Also used to attenuation.
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Cell culture
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Can't nudists of cells isolated from an organism and grown on surface of a medium or in broth.
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Cell culture
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Can't nudists of cells isolated from an organism and grown on surface of a medium or in broth.
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Diploid cell culture
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Created from embryonic animal, plant, or human cells that have been isolated and provide appropriate growth conditions. Last no more than 100 generations.
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Cell culture
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Can't nudists of cells isolated from an organism and grown on surface of a medium or in broth.
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Diploid cell culture
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Created from embryonic animal, plant, or human cells that have been isolated and provide appropriate growth conditions. Last no more than 100 generations.
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Continuous cell culture
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Longer lasting because they're derived from tumor cells.
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Cell culture
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Cells isolated from an organism and grown on surface of a medium or in broth.
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Diploid cell culture
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Created from embryonic animal, plant, or human cells that have been isolated and provide appropriate growth conditions. Last no more than 100 generations.
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Continuous cell culture
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Longer lasting because they're derived from tumor cells.
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Hela cell
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Type of continuous cell culture. Provide semi standard human tissue culture medium for studies on cell metabolism, aging, and viral infection.
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Viroids
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Extremely small pieces of RNA that are infectious and pathogenic in plants. Lack a capsid. Can appear linear. Can infect fungus.
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Prion
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Proteinacious infectious agent. Lacks instructional nucleic acid.
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Diseases caused by prions.
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Spongiform, encephalopathies, scrapie, kuru, CWD, and vCJD.
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Prp
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Cytoplasmic membrane protein that's anchored in lipid rafts and plays role in normal activity of brain.
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Cellular prp
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Normal alpha helix proteins. Globular.
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Cellular prp
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Normal alpha helix proteins. Globular.
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Prion prp
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Abnormal structure. Beta pleated sheet proteins. Can induce normal cellular prp to become prion prp.
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What does prion prp contain?
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Methionine as 129th amino acid.
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Transmission of prp diseases.
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Ingestion of infected tissues, transplant of infected tissues, or contact between infected tissue and mucous membranes or skin abrasions.
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How is prp disease destroyed?
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Incineration. Won't be killed by thorough cooking.
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Treatment of CJD.
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No cure. Use of anti malarial and anti psychotic drugs to slow it down.
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Flu pandemic of 1918-1919.
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50 million deaths. 10,000 deaths a week sometimes.
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Flu pandemic of 1918-1919.
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50 million deaths. 10,000 deaths a week sometimes.
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Family the flu belongs to.
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Orthomyxoviridiae.
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Structure of flu.
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Enveloped, negative single stranded RNA. Genome is segmented. Has to have 8 different segments to be infective.
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Two types of spikes flu virus has.
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Neuromenendase and hemagglutinin.
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What causes difference in strains?
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Spikes of virus.
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Slow prion infections
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Long incubation period, first noticed in Iceland when 100,000 sheep died.
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Slow prion infections
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Long incubation period, first noticed in Iceland when 100,000 sheep died.
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Theory one of where prions came from.
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May be abnormal versions of proteins. Prions induce production of more prions and when they accumulate, they interfere with neurological function.
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Theory two of where prions came from.
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Prions, which are found in normal cells, regulate production of neurochemical receptors in nervous system. Mutant prions could possibly trigger neurodegenerative diseases.
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Lysis of cells creates _______
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Plaque.
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Pocks
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Lesions in embryo mates chicken eggs.
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Focus
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Mass of live cells due to virus stimulated proliferation.
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Types of vaccines
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Inactivates, recombinant, or live.
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Bacterial viruses
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Phage shape complex symmetry, tail fibers, and spikes.
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How many people develop CJD each year?
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1 million.
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How many people develop CJD each year?
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1 million.
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Signs and symptoms of CJD.
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Loss of vision, speech, rapid mental deterioration, spastic paralysis. May take decades to develop.
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Unconventional agents
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Aka prion.
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Which flu type can flu shots not prevent?
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Flu type C.
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Type C infections
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Mild respiratory illness.
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Type A virus can be divided into subtypes based on which proteins?
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Hemagglutinin (15 subtypes) and neurominidase (9 subtypes).
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Antigenic drift
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Small continuous changes over time producing viruses not recognized by the immune system; can get sick. 1 virus mutates.
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Antigenic shift
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Abrupt major changes resulting in new H & H proteins. Most people have little or no protection.
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What changes does type A flu undergo?
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Antigenic shift and antigenic drift.
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What changes does type A flu undergo?
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Antigenic shift and antigenic drift.
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What type of changes does type B undergo?
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Only drift.
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All types of flu are found in _____.
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Birds.
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H5n1
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Hong Kong 1997. Avian flu. Not spread easily from person to person. Caused from chickens.
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H7N7
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Avian sporadic conjunctivitis.
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Current a subtypes
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H1N1 and H3N2.
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Influenza B
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No subtypes. Only among humans.
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Influenza A is found in which hosts?
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Different animals and humans.
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How many pandemics have there been in the last century?
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3.
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H1N1 is known as ____________.
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Spanish flu.
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Second pandemic
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1957-58. Asian flu aka H2N2. 70,000 deaths in US.
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Second pandemic
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1957-58. Asian flu aka H2N2. 70,000 deaths in US.
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3rd pandemic
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1968-1969. Aka Hong Kong flu. H3N2. 34,000 deaths in US.
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Potential flu pandemic scares.
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1. 1976 swine flu H1N1. 40 million vaccinated. Antigenic drift of 1918 virus.
2. 1997 avian flu. H5N1 in Hong Kong. Not spread easily. 3. 1999 H9N2 in Hong Kong. |
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Virulence
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Complex phenomenon that involved several features, including host adaption, transmission, tissue tropism, and replication efficiency.
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Edward Jenner
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Worked with cowpox. Father of immunology.
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Edward Jenner
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Worked with cowpox. Father of immunology.
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Vaccination
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Artificially acquired active immunity.
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Vaccine
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Attenuated, killed or parts of antigen - antibody production.
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Antibiotic
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Antimicrobial agent that is produced naturally by an organism.
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Antigen
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Molecule that triggers specific immune response.
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Antigen
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Molecule that triggers specific immune response.
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Antibody
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Proteinacious antigen binding molecule secreted by plasma cells.
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Attenuation
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Process of reducing vaccine virulence. Weakening antigen.
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Transduction
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Transfer of genes from one bacteria to another by a virus.
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Vaccine difficultues
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1. Hard to isolate and culture
2. Tissue cultures 3. Seek way to weaken or attenuate culture and still stimulate antibody production. 4. Use of animals to test. Animals must develop immunity vaccine. Must not make animal sick. 5. Long process 6. Viruses may mutate |
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Re assortment (recombination)
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Two strains of viruses can exchange genes and develop new characteristics.
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Antiviral cancer treatments
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Interferon, antibodies, prostaglandins, and synthetic compounds.
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Antiviral cancer treatments
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Interferon, antibodies, prostaglandins, and synthetic compounds.
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20 disease examples
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1. Aids
2. Mumps 3. Rabies 4. Hepatitis 5. Cowpox 6. Shingles 7. RSV 8. Ebolax 9. Measles 10. Herpes 11. TMV 12. Yellow fever 13. Rubella 14. Common cold 15. Influenza 16. Cold sores 17. Genital herpes 18. Smallpox 19. Parvo 20. Warts |
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Effects of viral infection on host cell.
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1. Lysis - lesions of culture cells.
2. Inclusion body formation - cytoplasm or nucleus and stained. 3. Changes in surface antigens - Novel antigens make cells target for immune system. 4. Interferon production - prevents infection of healthy cells. 5. Cell fusion 6. Affect function |
