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45 Cards in this Set
- Front
- Back
Basic Properties of the Polio Virus
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1. +ssRNA
2. Icosahedral 3. Nonenveloped 4. Infects nerve cells 5. RNA can read like mRNA |
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RNA plus strand
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Genome is read the same, not complementary
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Life Cycle
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1. Penetration and Uncoating
a. attaches to nerve cell, then cell engulfs 2. Genome Replication a. +RNA makes -RNA b. viral RNA-dependent, RNA polymerase; packaged proteing 3. Gene expression 4. Assembly and Release |
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Gene Expression
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- makes proteins
1. translation 2. auto-proteolysis and proteolysis |
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What virus can be translated without a eukaryotic 5' cap (methylguanosine cap? How?
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The Polio Virus inactivates translation of host mRNAs by DESTROYING THE HOST PROTEIN THAT RECOGNIZES THE METHYLGUANOSINE CAP.
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Basic Properties of Flu Virus
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1. -ssRNA
2. segmented genome (8 pieces) 3. enveloped 4. helical capsid 5. infects mucus membrane cells of the respiratory tract i.e., nose and lungs |
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What does the segmented genome of the flu virus do?
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virus can mix and match genomes, allowing virus jumping.
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Flu Virus Structure
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1. viral envelope
2. hemagglutinin, binds to cells 3. neuraminidase 4. segmented genome, -RNA |
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What kind of genome does the flu virus have?
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-ssRNA which means that it is read complementary to the mRNA
-segmented |
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Can the flu virus genome act as an mRNA strand?
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No it cannot because it is -RNA not +RNA which means the genome must first be transcribed in order to be translated
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What does Hemagglutinin do?
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mediates the fustion of the viral envelope to the host cell membrane
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What does Neuraminidase do?
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Breaks down the sialic acid (sticky), and assist in budding (the release of virus from cell)
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An Antigen Shift is?
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A change on the outer membrane proteins
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Major Changes in viral protiens are due to?
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mixing of segmented genomes between viruses which occurs when two different viruses infect the same host, intern producing new virus strains
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What is an Antigen?
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what the immune system recognizes
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HIV (AIDS Virus)
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Human immunodeficiency virus
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What does HIV attack?
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CD4+ or T-cells, which are part of the immune system. These are proteins out the outter surface of the cell.Tcells help other immune cells function
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How many CD4+ cells do healthy humans have?
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800 CD4+/T-cells per cubic millimeter of blood.
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When is an HIV patient considered to have AIDS?
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When their CD4+ count falls below 200.
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HIV facts (7)
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1. Usually acquired by sex
2. Almost always fatal 3. No cure 4. No Vaccine 5. in US 1/250 have it 6. in US 1/3000 are infected each year 7. 8-10 yrs pass between HIV infection and developement of AIDS |
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HIV Prevention (4)
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1. Celibacy
2. Insistence on condoms 3. Clean needles 4. Post-exposure drug treatment within 24hrs a. 4 wk treatment with possible side effects of headache, nausea, fatigue and anemia |
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How does HIV replicate?
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HIV is a retrovirus, which means its an RNA virus that replicates through a DNA intermediate.
The HIV RNA must first be transcribed into DNA via reverse transcriptase. It then encorporates itself into the host genome, and the host replicates the virus. |
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HIV structure
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1. Envelope protein, immune system response
2. reverse transcriptase 3. integrase, encorporates into our DNA 4. Protease, cuts polyprotein 5. +ssRNA |
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Gentic Map for retrovirus. 6 parts
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1. LTR= long terminal repeat
2. gag 3. pol 4. env 5. other genese (specific to virus) 6. LTR |
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GAG encodes for?
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internal structural protein like capsid protein.
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What does pol encode for?
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reverse transcriptase
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The envelope proteins are encoded by?
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env
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what are the HIV proteins (4)amd what are their functions?
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1. Viral envelope protein:
mediates binding to CD4 receptor 2. Reverse Transcriptase: synthesizes DNA from RNA template 3. Integrase: splices viral DNA into host genome 4. Protease: cleaves the viral polprotein into active parts |
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HIV reproductive cycle (7 steps)
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1. penetration and uncoating
2. reverse transcription 3. integration 4. gene expression 5. replication 6. polyprotein cleavage by HIV protease 7. assembly and budding |
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Once the virus is integrated into the host genome, what is it called?
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a provirus
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What are the 2 types of HIV treatment?
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1. Reverse transcriptase
inhibitors 2. Protease inhibitors Generally 2 reverse transcriptase inhibitors are used in combination with a protease inhibitor. |
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How does HIV develope drug resistance?
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via a mutation to the inhibitor binding site therefore allowing reactivation of protease function.
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What are Viroids?
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Virus like infections found in plants
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Properties of Viroids (3)
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1. circular ssRNA
2. naked RNA, no protein association 3. viroid genomes do not encode proteins |
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What are prions?
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infectious proteins which appear to transmit disease without DNA or RNA
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What is the name of the prion diseases?
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spongiform encephalopathies, (makes brain look like a sponge)
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Types of Prion disease (3)
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1. Scrapie in sheeps/goats
2. Mad Cow Disease 3. Creutzfeld-Jacob in humans over 50 |
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Mad Cow Disease is also known as?
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Bovine spongiform encehphalopathy (BSE)
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what are the sources of BSE?
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Feeding cows with *meat and bone meal* remains of infected sheeps or cows, especially infected brain tissue
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Is a prion destroyed by cooking?
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Nope
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What is the New variant Creutzfeld-Jacob syndrome?
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Basically mad cow disease, in people under 30. most people die
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What is the incubation time for mad cow disease?
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10 to 15 years
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How do prions cause disease?
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they're kind of like vampires, a normal protein comes in contanct with an infected protein. the diseased protein catalyzes a conformational change that turns the normal protein into a prion.
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The prion gene is
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a mutant form of a normal gene.
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Where are prions found?
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in normal genee found in animals.
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