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45 Cards in this Set

  • Front
  • Back
Basic Properties of the Polio Virus
1. +ssRNA
2. Icosahedral
3. Nonenveloped
4. Infects nerve cells
5. RNA can read like mRNA
RNA plus strand
Genome is read the same, not complementary
Life Cycle
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
Gene Expression
- makes proteins
1. translation
2. auto-proteolysis and proteolysis
What virus can be translated without a eukaryotic 5' cap (methylguanosine cap? How?
Basic Properties of Flu Virus
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
What does the segmented genome of the flu virus do?
virus can mix and match genomes, allowing virus jumping.
Flu Virus Structure
1. viral envelope
2. hemagglutinin, binds to cells
3. neuraminidase
4. segmented genome, -RNA
What kind of genome does the flu virus have?
-ssRNA which means that it is read complementary to the mRNA
Can the flu virus genome act as an mRNA strand?
No it cannot because it is -RNA not +RNA which means the genome must first be transcribed in order to be translated
What does Hemagglutinin do?
mediates the fustion of the viral envelope to the host cell membrane
What does Neuraminidase do?
Breaks down the sialic acid (sticky), and assist in budding (the release of virus from cell)
An Antigen Shift is?
A change on the outer membrane proteins
Major Changes in viral protiens are due to?
mixing of segmented genomes between viruses which occurs when two different viruses infect the same host, intern producing new virus strains
What is an Antigen?
what the immune system recognizes
HIV (AIDS Virus)
Human immunodeficiency virus
What does HIV attack?
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
How many CD4+ cells do healthy humans have?
800 CD4+/T-cells per cubic millimeter of blood.
When is an HIV patient considered to have AIDS?
When their CD4+ count falls below 200.
HIV facts (7)
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
HIV Prevention (4)
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
How does HIV replicate?
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.
HIV structure
1. Envelope protein, immune system response
2. reverse transcriptase
3. integrase, encorporates into our DNA
4. Protease, cuts polyprotein
5. +ssRNA
Gentic Map for retrovirus. 6 parts
1. LTR= long terminal repeat
2. gag
3. pol
4. env
5. other genese (specific to virus)
6. LTR
GAG encodes for?
internal structural protein like capsid protein.
What does pol encode for?
reverse transcriptase
The envelope proteins are encoded by?
what are the HIV proteins (4)amd what are their functions?
1. Viral envelope protein:
mediates binding to CD4
2. Reverse Transcriptase:
synthesizes DNA from RNA
3. Integrase: splices viral
DNA into host genome
4. Protease: cleaves the
viral polprotein into
active parts
HIV reproductive cycle (7 steps)
1. penetration and uncoating
2. reverse transcription
3. integration
4. gene expression
5. replication
6. polyprotein cleavage by
HIV protease
7. assembly and budding
Once the virus is integrated into the host genome, what is it called?
a provirus
What are the 2 types of HIV treatment?
1. Reverse transcriptase
2. Protease inhibitors

Generally 2 reverse transcriptase inhibitors are used in combination with a protease inhibitor.
How does HIV develope drug resistance?
via a mutation to the inhibitor binding site therefore allowing reactivation of protease function.
What are Viroids?
Virus like infections found in plants
Properties of Viroids (3)
1. circular ssRNA
2. naked RNA, no protein
3. viroid genomes do not
encode proteins
What are prions?
infectious proteins which appear to transmit disease without DNA or RNA
What is the name of the prion diseases?
spongiform encephalopathies, (makes brain look like a sponge)
Types of Prion disease (3)
1. Scrapie in sheeps/goats
2. Mad Cow Disease
3. Creutzfeld-Jacob in
humans over 50
Mad Cow Disease is also known as?
Bovine spongiform encehphalopathy (BSE)
what are the sources of BSE?
Feeding cows with *meat and bone meal* remains of infected sheeps or cows, especially infected brain tissue
Is a prion destroyed by cooking?
What is the New variant Creutzfeld-Jacob syndrome?
Basically mad cow disease, in people under 30. most people die
What is the incubation time for mad cow disease?
10 to 15 years
How do prions cause disease?
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.
The prion gene is
a mutant form of a normal gene.
Where are prions found?
in normal genee found in animals.