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22 Cards in this Set
- Front
- Back
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viruses
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tiny infectious agents
obligate intracellular parasites lack machinery for generating energy and large molecules= no metabolism need host to replicate themselves contains DNA or RNA; not both |
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viron
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single infectious particle; neither pro or eu; composed of nucleic acid and protein
are host and tissue specific (viral specificity) |
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bacteriophages (phage)
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viruses that infect bacteria only
(ones that infect animal cells are just viruses) |
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viral component: genome
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whole set of DNA or RNA
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viral component: capsid
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shape is derived from this
composed of protein subunits called capsomeres -- immunogenic (ability of a particular substance to provoke an immune response) |
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viral component: envelope
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loosely covers some viruses
derived from its host: lipids and proteins |
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viral components: glycoprotein spikes
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aid in attachment of viruses to host cell
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viral classifications...
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DNA or Rna
double/single stranded shape envelope presence |
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lytic cycle
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typically considered the main method of viral replication, since it results in the destruction of the infected cell.
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lysogenic cycle
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integration of the bacteriophage nucleic acid into the host bacterium's genome
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latent lifestyle
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DNA of virus integrates into the host genome and becomes silent
Sometimes, new properties are given to the host of the provirus |
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Animal Viruses Enter Host by Two Ways:
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1: fusion- enveloped ex: HIV
nonlethal 2: endocytosis: naked ex: adenovirus LETHAL |
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Cultivating methods
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most common:
chick embryos and cell cultures = monolayers of cells |
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Cytopathic effect
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expose tissue cells to virus and look for structural changes or damage
ex: Syncytia |
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plaque formation
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lysis of cells growing confluently in culture by animal viruses
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electron microscopy
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a form of ID and detection
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indirect detection: serological testing
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screening for viral antibodies present in a person’s blood
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Rivers' postulates
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*Expansion of Koch’s postulates to include viruses
-filtrates of the infectious material shown to be free of bacteria or other cultivatable organisms -must produce disease or it’s counterpart (in tissue culture) -or the filtrates must produce specific antibodies in the appropriate animals |
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Viruses may cause 20% percent of human cancers
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Viruses may cause 20% percent of human cancers
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Oncogenic (cancer-causing) viruses
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Herpesviruses, Epstein-Barr virus, human T-cell leukemia virus, human papilloma virus (HPV)
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Prions
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infectious proteins
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prions cause...
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abnormal PrPsc (due to a mutation) converts normal PrPc of the brain
EX: Mad cow disease, Transmissible spongiform encephalopathies (TSEs), variant Creutzfeldt-Jakob disease are all neurological degenerative diseases Sponge-like holes in brain tissue: loss of coordination, appetite, dementia |
