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24 Cards in this Set

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  • Back
Define Virus
A small, obligatory intracellular organism that contains either a DNA or an RNA genome, encapsidated in a protein shell that oftentimes is further packaged in a lipid envelope
What are some basic properties of viruses
100x smaller than a cell
Need host cells, embryos, or whole animals to cultivate (obligate intracellular parasites)
Viruses replicate like their hosts, so there are few drug targets
Full range of infections
Confusingly similar symptoms, e.g. "flu like," rash
Often suspects in diseases with unknown etiologies
Difficult to diagnose/differentiate, cultivate, and treat
What is the name of the protein shell that encloses the nucleic acid
Capsid
What is the name of the capsid together with its enclosed nucleic acid
Nucleocapsid
The nucleocapsid may be wrapped in what, which is derived from host cell membranes
An Envelope
What word describes a complete infectious virus particle
Virion
What is the morphology of the adenovirus
Icosahedral
What is the morphology of the Ebola virus
Helical
What is the morphology of the Pox virus
Complex
What are the two main classifications used for viruses
Nucleic Acid Structure: RNA or DNA
Enveloped or non-enveloped
What do Pox, Herpes, Adeno, Papova, Hepadna, and Parvoviruses all have in common
They are DNA viruses
What do Paramyxo, Orthomyxo, Arena, Filo, Rhabdo, Bunya, Retro, Flavi, Toga, Reo, Calici, and Picorna viruses have in common
They are RNA viruses
What is a negative-sense genome
It is complementary to mRNA. It is a component of RNA viruses. These viruses have RNA-dependent RNA polymerase packaged in the viron
What is a positive sense genome
mRNA-sense. These RNA viruses can directly translate viral genome to produce RNA-dependent RNA polymerase for viral replication
What is meant by quasi-species in viral genetics
Sequence variants within the virus population in an infected host. Often seen in RNA viruses, whose RdRP lacks proofreading, causing errors to occur at high frequency
What is meant by re-assortment in viral genetics
Influenza virus type A has a segmented genome and large animal reservoirs, so it can get re-assortment of large pieces of its genome- "antigenic shift"
What determines viral stability and the entry pathway
The virus coat.
What type of viruses are non-enveloped
Frequently enteric, such as enterovirus, enteric adenoviruses, and reovirus
How do enveloped viruses gain entry to the host
Respiratory droplets, saliva, semen, blood, close contacts. Examples include influenza, measles, and EBV
What virus lyses neuronal cells
Poliovirus
What viruses induce cell fusion (syncytia)
HIV, measles
Name two viruses that shut down/hijack host cellular processes
HSV, Poliovirus
Most immune pathology in viral infections is caused by what
T cells (rashes), sometimes by antigen-antibody immune complexes (kidney)
What is RSV disease mediated by
Cytokines from Th2 cells. This is the reason inactivated vaccine was problematic