Term
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Definition
| A package of genetic information protected by a protein shell for delivery into a host cell to be expressed and replicated. |
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Term
| What differentiates Viruses from other micro-organisms? |
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Definition
Nucleic acid - have only DNA or RNA, not both.
Lack a nuclear or external cell wall
Small genomes - produce only a limited number of proteins and have no intracellular systems.
Can only reproduce inside other cells (steal energy and mechanics of the host). |
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Term
| Historically significant viruses |
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Definition
Polio
Small pox and Measles
Spanish Flu - after WWII killed many many many.
Nowadays - west nile, SARS, avian flue, pandemic influenza viruses. |
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Term
| Viral taxonomy is based on? |
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Definition
Type and form of nucleic acid
Structure
Organization of genome
Antigenic differences. |
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Term
| Genomic Organizations of viral nucleic acid |
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Definition
RNA - single, double.
DNA - single double. |
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Term
| Single Stranded RNA - positive vs negative. |
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Definition
Pos - same direction as mRNA - can go directly to the ribosome and synthesize viral proteins.
Neg - must make a positive copy inside the cell to be translated. |
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Term
| Double stranded RNA - two types. |
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Definition
| Single piece or segmented(each segment codes for a different viral protein - mixing results in swine and avian flu). |
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Term
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Definition
Integrated into the genome.
Ex. Herpes virus. |
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Term
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Definition
| Structural subunits containing several proteins, aggregate together to form the viral capsid. |
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Term
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Definition
| Associates with viral DNA to produce a nucleocapsid. |
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Term
| Arrangements of nucleocapsid |
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Definition
Cubic - icosahedral(herpes) - 20 sides.
Helical - influenza virus.
Complex |
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Term
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Definition
lipid structure, derived from cellular membranes(stolen from host).
Studded with surface projections.
Glycosylated by host systems to make them "sticky". |
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Term
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Definition
| Naked Icosahedral DNA virus. |
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Term
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Definition
| Envelopped Icosahedral DNA virus |
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Term
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Definition
| Enveloped icosahedral DNA virus |
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Term
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Definition
| Enveloped Helical RNA virus |
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Term
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Definition
| Naked, Icosahedral, RNA virus. |
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Term
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Definition
| From mother to fetus in utero. |
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Term
| Phases of viral life cycle: |
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Definition
1. Attachment and internalization
2. Uncoating (cell uncoats it, hoping to destroy it).
3. Replication - Naked nucleic acid will synthesize protein(to become the next virus).
4. Assembly - DNA surrounds itself with capsomere proteins etc..Steals nuclear envelop and glycoproteins.
5. Egression - leave the cell. |
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Term
| Consequences of Virus-Cell Interaction |
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Definition
Viral proliferation and cell lysis - host cell dies. Ex. Cold sores, Genital Herpes, Chicken pox.
Latent Infection - non-replicating virus. Can become integrated. Ex. HPV, Herpes.
Persistent Infection - ongoing viral replication, few or no symptoms. Ex. Hep C and B, HIV. Tissue injury may be induced by the virus or the immune response to the viral infection.
Oncogenesis - Cellular proliferation. HPV and cervical cancer. Hep B and C can cause liver cancer. EB - lymphoma.
No apparent Disease - Hep G. |
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Term
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Definition
Clinical features typical to infection.
Lab Dx - histology and cytology, looking for viral antigens in tissue and serum, Antibody testing( IgG, IgM, very high IgG titer), virus isolation, DNA or RNA amplification. |
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Term
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Definition
Proteinaceous infections particles.
An infectious agent composed of a protein. Does not self replicate, induces existing proteins to take on the rogue form. Highly resistant to heating and irradiation. |
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Term
| Examples of Spongifrom encephalopathies |
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Definition
Human - Creuztfeldt-Jacob disease.
Animal - BSE(mad cow). |
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