Term
| VAP = ?, attached to? attaches to? |
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Definition
| Virus attachment protein, capsomere/peplomer, cell surface receptor |
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Term
| What cells are able to interact with VAP? |
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Definition
| Only those with viral receptors |
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Term
| A "resistant" cell has no _____? |
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Definition
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Term
| What is one of the ways that viruses enter the cell? |
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Definition
| They are endocytosed, but still have to cross the endosome membrane |
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Term
| How do naked virions always enter cell? |
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Definition
| endocytosed, acid catalyzed step in endosome that causes change in structure, allows virus into the cytoplasm |
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Term
| How do SOME enveloped viruses enter the cytoplasm? |
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Definition
| endocytosed, then low pH activates fusion peplomer |
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Term
| How do SOME enveloped viruses enter the cytoplasm? |
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Definition
| endocytosed, then low pH activates fusion peplomer |
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Term
| How do other enveloped viruses enter the cell? |
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Definition
| They have fusion peplomer active at a neutral pH and fuse directly with the cell membrane |
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Term
| Define an "uncoated" virus |
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Definition
| A virus that has released its genome into the cell |
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Term
| What helps uncoat a virus? |
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Definition
| Cell/viral proteases (this can include matrix proteins) |
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Term
| Where do icosahedral DNA viruses release their genome? |
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Definition
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Term
| Replication of RNA viruses occur in the ___ ? Except (2) |
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Definition
| cytoplasm; orthomyxoviruses (influenza) and retroviruses |
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Term
| Genome replication and nucleocapsid assembly for DNA viruses occurs? Except (2)? |
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Definition
| in the nucleus; poxviruses and Hep B |
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Term
| Where does all viral protein synthesis occur? |
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Definition
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Term
| Positive strand RNA viruses use ____ as mRNA? |
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Definition
| their genomes, except retroviruses |
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Term
| What translates the viral mRNA? |
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Definition
|
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Term
| What do negative strand and double strand RNA viruses have in virion for replication? |
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Definition
| RNA-dependent RNA polymerase (makes transcriptase - for mRNA - and replicase - for new genomes) |
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Term
| How do positive strand RNA viruses replicate their genome? |
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Definition
| One of their translation products is a replicase (RNA dependent RNA polymerase) that makes a negative strand copy of the genome, which is copied to make new positive strand genomes (which are encapsulated) |
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Term
| How is negative strand RNA virus genome copied? |
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Definition
| Replicase in virus makes positive strand copies of the genome which are copied to make new (-) strand genomes which are encapsulated with replicase in new virus |
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Term
| Where is uncoated influenza virus transcriped and genome replicated? Where is nucleocapsid assembly? |
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Definition
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Term
| How do double-stranded RNA viruses replicated their genome? |
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Definition
| They have virion transcriptase/replicase that copies the (-) strand to make mRNA and then copies each strand to make new genomes (conservative) |
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Term
| What is the mechanism for retrovirus RNA genome replication? |
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Definition
| They have a virion enzyme system that makes a double stranded DNA copy of the RNA genome, transports it to the nucleus, integrates into a cellular chromosome, and provides a template for mRNA and genomic RNA synthesis |
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Term
| What is the key of DNA virus replication? |
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Definition
| Temporal Regulatory classes (early and late phases) |
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Term
| What do immediate early proteins do? |
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Definition
| They are regulatory, enter the nucleus and target cell genes (alter promoters etc) to make viral replication favorable |
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Term
| What RNA is expressed following immediate early mRNA? Function? |
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Definition
| Early RNA is expressed and early proteins made - mostly for genome replication |
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Term
| After early mRNA is expressed, what happens next? |
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Definition
| Late proteins/RNA are now expressed by virus that make up the structural components of the virus |
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Term
| T/F DNA viruses use cell machinery exclusively for translation? |
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Definition
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Term
| T/F DNA viruses use a combination of cell/viral machinery for replication, assembly, and transcription? |
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Definition
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Term
| Which 3 viruses do not have a distinction between immediate early and early gene expression? |
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Definition
| Parvo, polyoma, and papillomaviruses |
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Term
| Which DNA virus has a replication cycle like retroviruses? |
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Definition
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Term
| Which DNA virus replicates completely in the cytoplasm and assembles in virus factories? |
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Definition
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Term
| Which virus uses its own enzymes for all DNA/RNA synthesis? |
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Definition
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Term
| How do helical RNA viruses leave the host cell? |
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Definition
| They are enveloped by host cell wall and budding takes place to mark envelope with viral proteins (peplomers) |
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Term
| T/F All enveloped viruses acquire their envelope at the plasma membrane? |
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Definition
| False - others bud into other cytoplasmic membranes |
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Term
| How is the herpesvirus enveloped? |
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Definition
| Enveloped/deenveloped at nuclear membrane then final envelope from cytoplasmic membranes |
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Term
| How does Poxvirus acquire its envelope? |
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Definition
| it synthesizes and assembles envelope de novo from cytoplamsic membrane fragments |
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Term
| What is a permissive cell? |
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Definition
| one that allows a complete viral cycle, including release of infectious virus |
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Term
| What is a non-permissive cell? |
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Definition
| One that takes up virus but does not allow infection to be completed |
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Term
| T/F all viruses kill infected cells? |
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Definition
|
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Term
| T/F viruses can disrupt host DNA, RNA, and protein synthesis? |
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Definition
|
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Term
| T/F viral gene activity can alter cell morphology? |
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Definition
| True - this can be useful for diagnosing infection under microscope |
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Term
| How does the poliovirus change infected cell morphology? |
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Definition
| rounding, monolayer damage |
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Term
| What are "inclusion bodies" seen under microscope of measles virus? |
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Definition
| accumulation of eosinophilic protein debris |
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Term
| What is a lytic virus infection? |
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Definition
| Virus production with cell death |
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Term
| What is an abortive viral infection? |
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Definition
| infection of non-permissive cells, no virus production |
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Term
| What is a persistant viral infection? |
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Definition
| long-term virus-cell association with cell survival |
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Term
| What are the 3 stages of a persistant viral infection? |
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Definition
| Chronic - replication;latent - no replication, but some viral gene expression; Recurrent - latent and lytic periods |
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Term
| What do cells try and do if they recognize they are being taken over by a virus? |
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Definition
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Term
| What do transforming viruses do to prevent cell apoptosis? |
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Definition
| turn on cell oncogenes on purpose and by accidental damage promoted by abnormal cell proliferation |
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Term
| What is the role of an interferon? how activated? |
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Definition
| Inhibits viral translation, induces apoptosis, upregulates MHC, and diffuses to neighbor cells (to stop their infection); activated by double stranded RNA |
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Term
| How does cell respond to immediate early proteins that try to upregulate growth? |
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Definition
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Term
| What does the virus do to stop interferons/apoptosis? |
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Definition
| Viral gene products can interrupt interferon signaling and encode anti-apoptotic proteins |
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