Term
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Definition
◦ Obligate intercellular parasites
◦ Consist of DNA or RNA genome and protein coat |
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Term
| What is the shape and make up of a virus? |
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Definition
| diversity of structure and genetic material |
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Term
| What are 4 types of viruses and their shapes? |
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Definition
Tobacco mosaic virus-capsomere of capsid made of RNA
Adenovirus--capsomere of DNA in the form of a stop sign
Influenza virus-Made up of RNA a circle of clycoproteins, membranous envelope with capsid and Rna on the inside
Bacteriophage T4-head, tail sheath, tail fiber |
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Term
| What are the 6 classes of animal viruses? |
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Definition
dsDNA- Double stranded DNA
ssDNA- Single stranded DNA
dsRNA- Double stranded RNA
ssRNA- Single Stranded RNA
ssRNA- Template for mRNA Synthesis
ssRNA-Template for DNA synthesis |
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Term
| What is the life cycle of the virus? |
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Definition
1-Entry and uncoating
2-Replication
3-Transcription and manufacture of capsid protein
4-Self-assembly of new virus particles and their exit from the cell
(deeper understanding)
Viral genome infects cell
Uncoats
Uses host machinery to:
Replicate genome
Express viral proteins
Virus particles self-assemble
Virus exits host cell
Most damage occurs on exit
In some cases transcriptional regulation of cellular genes
is altered by viral insertion into host genome or by virusderived
transcription factors → cancer |
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Term
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Definition
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Term
| what does the lytic cycle result in? |
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Definition
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Term
| describe the lysogenic cycle |
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Definition
Integrates into host genome
Doesn’t kill cell
Can become lytic later |
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Term
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Definition
◦ Protein shell around virus
Diverse in shape and size |
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Term
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Definition
◦ Present in some viruses
◦ Membrane around capsid
◦ Derived from host membrane
◦ Contains glycoproteins
Help virus infect other cells |
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Term
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Definition
◦ Viruses infect specific species and
specific tissues
Due to molecules on viruses
interacting with specific host cellsurface
proteins
◦ Can be broad or narrow
West Nile Virus infects birds,
mammals, even alligators.
Particularly deadly in corvids (crows,
magpies), horses
Polio is human-specific – wipe it out
in humans and it will be gone for
good |
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Term
| What are treatments for viral infection? |
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Definition
◦ Vaccination
Use hobbled virus to raise antibodies that will attack
virus and keep it from infecting cells
Example: small pox, flu
◦ Treat symptoms
Example: cold
◦ Slow progression of infection
Example: HIV |
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Term
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Definition
◦ Require RNA to be copied
to DNA
Reverse Transcriptase (RT,
RTase)
◦ Example:
Human immunodeficiency
virus (HIV) |
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Term
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Definition
◦ Invades cells of immune system
White blood cells
◦ Can exist as provirus
Integrates into host genome
◦ Reverse transcriptase is error prone
High mutation rate, fast evolution
By the time immune system responds,
virus has changed enough not to be
recognized
Defeats attempts at a vaccine
Rapidly develops drug resistance |
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Term
| What are people trying to do to treat HIV? |
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Definition
Currently available:
RTase inhibitors
Premature termination of transcription
Irreversible inhibition of enzyme
Protease inhibitors
Envelope protein must be clipped
Fusion inhibitors
Block viral envelope from fusing with cell membrane
Integration inhibitors
Prevent DNA copy of virus from inserting into genome |
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Term
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Definition
Dideoxynucleotides prevent elongation,
lead to premature termination |
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Term
| What is a protease inhibitor? |
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Definition
HIV’s mRNA is translated into a single
polypeptide with several domains
One of the domains is a protease (an
enzyme that cuts proteins)
The protease must separate the
domains into individual proteins for
each to function
• capsid
• envelope proteins
• RT
• transcription factors
Protease inhibitor blocks protease,
prevents function of viral proteins
within cell and formation of new virus |
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Term
| What are some problems with treating hiv? |
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Definition
Because retroviruses have high mutation rate, they develop
resistance to individual drugs
Hit with three drugs at once, making it difficult for a single virus
to adapt to all three at the same time |
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