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24 Cards in this Set
- Front
- Back
Immune response to viruses type 1 IFN... |
type 1 interferons limit the infection within tissues e.g. IFN alpha IFN beta Innate lymphocytes: NK cells, gamma-delta T cells Adaptive immune response CD4 and CD8 T cells recognise and destroy viruses, resolve acute infection, immuno-surveillance for latent infections e.g. HSV |
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Viruses are |
obligate intracellular parasites |
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Viruses features unique to viruses... |
no metabolic activity outside of host close virion (virus particle) made of nucleic acid genome protected by a capsid, surrounded by an envelope |
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Classifying viruses Questions to ask? |
according to genome Is the genome DNA? is the genome double stranded? is the RNA genome sense? dose it use reverse transcriptase enzyme? |
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what is ambisense? example of an ambisense virus? |
Ambisense virus - RNA genome is sense and antisense Lassa fever |
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DNA vs RNA viruses |
I II VII are DNA rest are RNA |
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Baltimore classification of Viruses: Class I examples? |
ds DNA virus
HSV, adenovirus |
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Baltimore classification of Viruses: Class II |
ssDNA virus Parvovirus |
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Baltimore classification of Viruses: Class III examples? |
dsRNA virus Retroviruses, Bluetongue |
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Baltimore classification of Viruses: Class IV examples? |
sense RNA virus
HCV, Polio, Yellow fever |
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Baltimore classification of Viruses: Class V examples? |
Antisense RNA virus Influenza, Ebola, Measles |
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Baltimore classification of Viruses: Class VI examples? |
RNA reverse transcribing virus HIV, HTLV-1 (retrovirus) |
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Retroviruses why is it different to central DNA dogma? |
central dogma DNA → RNA → protein but retroviruses RNA → DNA → RNA → protein |
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Baltimore classification of Viruses: Class VII examples? |
DNA reverse transcribing virus HBV |
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Virus |
capsid icosahedral virus - adenovirus helical virus - Ebola |
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Replication |
Viruses only replicate wen they infect a host cell capsid is partially disassembled virus directs cell to synthesise viral components |
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Viral components |
3 types 1. essential replication factors - for genome synthesis 2. subunits assembled for new capsid and virioins 3. Copies of viral genome - packaged in new capsids |
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Eclipse phase which phase in "life cycle" of virus? |
during this new components are made, infectious virus cannot be recovered |
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Virus release phase which phase in "life cycle" of virus? |
viral genome has replicated → viral proteins synthesised progeny virus can be assembled new viruses may be released by budding/cell lysis |
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Virus receptors where are they? |
outside of the virus has receptors if the receptor is highly specific can be human restricted e.g. polio binds to decay accelerating factor (DAF) in humans if receptor is not very specific can infect different species e.g. swine flu |
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extent of damage to host cytopathic virus? |
cytopathic viruses - completely destroy target cell by cell lysis e.g. non-enveloped viruses polio, adenovirus viruses affect cells in a minor way show chronic infections some viruses show latency, virus does not replicate but stays quiescent for long periods |
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identifying viruses in the laboratory ELISA methods |
viruses don't grow in cultures ELISA based methods Enzyme Linked ImmunoSorbent Assay identify by antigens or by detecting antibodies to the virus as long as the virus is common and known this is quick cheap and effective |
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identifying viruses in the laboratory PCR |
PCR using primers specific for suspected pathogen in array with several other candidates rapid diagnostic assay used when ELISA can't detect viruses can be used for unknown viruses |
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Types of virus infections acute infection? persistent infection smouldering? persistent infection latent? persistent infection slow? |
Acute infection e.g. Rhinovirus, Influenza Persistent infection, smouldering e.g. Lymphocytic choriomeningitis Persistent infection, latent e.g. HSV blue line - level of virus in the orhganism red bar - when symptoms are seen Persistent infection, slow e.g. Measles, HIV |