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103 Cards in this Set

  • Front
  • Back

Can HPV cause cancer?


virus analogy

spaceship without fuel tanks

virus can't make energy by itself

virus analogy

drifts in space until in can dock in a mother-ship

viruses needs to attach to cells to take energy from it

virus analogy

when it docks, it offloads cargo

what is the cargo?

the cargo is the viral genome, allowing the virus to make clones

virus analogy

Clones leave mothership and drift, looking for their own niche

the new virus cells leave the host cell, and infect other cells

Virus biology

they are infectious particles, but not living cells

Viruses and doctor visits

Viruses are responsible fro the majority of visits to family physician

viral transmission

blood transfusion

mucus droplets






Virus and antibiotics

antibiotics can't be used on viruses b/c it doesn't have the cellular processes and units that antibiotics will use to find bacteria

virus treatment

viruses must be treated with different therapeutic strategies than other microorganisms

Virus Vs. Bacteria


10-500nm vs 500- about 2000 nm

small vs big

Virus Vs. Bacteria

reproduction dependence

can only multiply inside of cells Vs. can multiply in the absence of other cells

Virus Vs. Bacteria

genetic material(s)

DNA or RNA, never both Vs. Always both DNA and RNA

Virus Vs. Bacteria


few enzymes Vs. many enzymes

Virus Vs. Bacteria

ribosomes and enzymes for metabolizing nutrients

none vs contains ribosomes and enzymes for metabolism of nutrients

Virus and metabolism

viruses can't metabolize proteins or make use of nutrients

Virus can be seen with..

electron microscope

Virus size

smaller than bacteria

30-300nm diameter

virus shape

viruses can change its shape depending on environment

envelope virus

has a membrane around it

naked virus

only has covering made out of protein

other name for virus



complete infectious viral particle with nucleic acid surrounded by a protein coat


complete unit of a virion

make up of nucleoclaspid

RNA or DNA + capsid- protein coat


make up the protein coat capsid

liquid envelopes

a fluid membrane outside of the nucleocapsid

glycoproteins/ spikes

inserted in envelopes or capsid

influenza virus structure

influenza virus structure

influenza A is enveloped

it is one of the most dangerous types of Influenza

Virus range

usually can infect every life form- bacteria, fungi, plants, animals, humans

virus host range or specificity

usually viruses are specific to one type

example of virus host range or specificity

ex. bacteriophage infects only bacteria


viruses that infect bacterial cells

bacteriophages function

transfer new genes from one bacteria to another

bacteriophages function:

genetic engineering

can be used as tool for genetic engineering

ex. production of human insulin from e.coli

bacteriophages function:


can transfer genes for production of toxin

classifying viruses

viruses are grouped into families based on DNA/RNA composition and structure

DNA vs. RNA viruses

which type of virus mutates quickly?


DNA viruses

1. Papillomaviridae (HPV)

2. Adenoviridae (adenovirus)

3. Hepadnaviridae (hepatitis B)

4. Herpesviridae (HSV-1 & -2, HHV-3)

5. Poxviridae (smallpox, monkey pox, etc.)

6. Parvoviridae (B-19)

RNA viruses

1. retroviridae (HIV)

2. Flaviviridae (Yellow fever virus, West Nile virus)

3. orthomyxoviridae (Influenza A,B,C)

Attachment and penetration into host cell:


usually used by enveloped virus; the virus fuses its envelope with the plasma of the cell and once its in, it releases its nucleic acid and begins replication

Attachment and penetration into host cell:


usually used by naked virus; the virus pulls itself down the membrane



dna to rna to mrna replication of dna

DNA Virus

host cell DNA polymerase may be used directly to make more virus DNA

RNA virus

virus carries its own RNA polymerase enzyme to produce RNA from viral RNA ( No RNA polymerase in host cells)

RNA retrovirus

carries its own reverse transcriptase enzyme in the virus capsid.

integrated viral DNA is then transcribed by host cell polymerase and makes more virus RNA

ex. HIV

Reverse transcriptase

makes ssDNA from ssRNA, then dsDNA is formed and intergrates with the host DNA in chromosome

DNA dependent DNA polymerase

DNA viruses uses DNA dependant DNA polymerase either host or virally derived for replication of genome

viral DNA->viral DNA

RNA Dependent RNA polymerase

RNA viruses use RNA Dependent RNA polymerase for replication of genome.

RNA viruses must carry this enzyme into the cell

viral RNA-> viral RNA

RNA dependent DNA polymerase= reverse transcriptase

retrovirus uses RNA dependent DNA polymerase/ reverse transcriptase to make DNA

Assembly and Release of New Virus

newly replicated RNA or DNA associate with newly made viral proteins to create new nucleocapsids

Assembly and Release of New Virus

if enveloped virus

envelope components are produced and inserted into the host cell plasma membrane, viral particles then attached to the plasma membrane and buds through

antiviral drugs:


stops entry (fusion) of HIV into cells

antiviral drugs:


stops replication of herpes viruses by interfering with viral DNA polymerase

antiviral drugs:


Highly Active AntiRetroviral Therapy- combination of antiviral drugs used to stop replication of HIV

helps prevent virus from becoming resistant to drugs

antiviral drugs:

TamiFLu oseltamivir

stops budding release of influenza virus from cell

Host-Virus Interactions

acute/productive infection

virus replicates, produces many virions

host cells often killed- lytic infection

lytic infection

means cell will explode

Host-Virus Interactions

Latent infection

viral genome persists in host cell but does not replicate.

At a later time, with the right environment, will grow.

Can lay dormant for years

Host-Virus Interactions

chronic infection

virus replicates w/o causing host cell lysis and can persist for long periods of time

Chicken pox: acute infection that becomes latent

1. fever, itchy, rash

2. rash spreads mainly on trunk and head

3. more rash=sever illness

4. most children have 250-500 skin lesions

5. skin lesions can get secondary infections

6.virus inrash escapes via airborne

7. skin vesicles present in different stages of lesion formation

Chicken Pox becomes latent

virus is present in cells, sitting in ganglia.

doesn't replicate until triggered by external factors


second outset of latent chicken pox

cause of shingles

trigger is mainly age, the decline of immune system

stress also affects onset of singles

shingles and symptoms

rash and pain

untreated rash can stay for 2-5 weeks


untreated shingles

can lead to chronic nerve pain, must stop replication asap

shingles and lesions

skin bacteria can be exposed to lesions by scratching rashes, flesh eating disorder can occur

chicken pox/shingles transmission

airborne through vesicles

can be spread during 14 day incubation period of vesicles

Chickenpox complications

most common complication is inmmunocompromised is secondary bacterial infection

1. CNS Disease: encephalitis, meningitis, etc.

2. Hemorrhagic complications: neutropenia and thrombocytopenia

3.Primary vacirella pneumonia

Chickenpox parties

bad idea, increases chance for flesh eating disease

Zoster/shingles complications

development of PHN Post Herpatic Neuralgia, causes chronic pain and permanent nerve damage, can cause blindness

Active immunization

live attenuated vaccine, higly protective, memory cells produced

can be included with MMRV

Passive immunization

Effective when used for exposed patent up to 3 days post-exposure

Passive Immunization: VZIG: varicella-zoster immunoglobulin

used for immunocompromised exposed children and neonates born to mothers with varicella

Antivirals: Acyclovir and analogues treatment

treatment must start within 2-3 days of debut of shingles lesions to prevent PHN

chickenpox in normal individuals are not treated with antivirals

oncogenic viruses

transform normal host cells to cancer cells

can be RNA or DNA viruses

Oncogenic viruses exception

not all 'transformed' cells become cancerous

ex. wart virus often benign tumors

Epstein-barr virus

causes Burkitt's Lymphoma most common cancer in Africa

viral diagnosis:


polymerase chain reaction

molecular biology technique used to detect the genes in an organism

viral diagnosis:


patient specimens added to cultured cells and after a period of growth, observed for CPE (cytopathic effects) on cultured cells

labour intensive, slow- depends on viral growth rates

Syncytia- a type of CPE

one cell got infected by a virus, the clump of cells that was around the infected cell become one big cell with lots of nuclei, almost like a virus factory, making and pouring out cells

once cell doesn't have energy, cell will die causing inflammation

Influenza A: FA Stain

DFA- Direct Fluorescent antibody test for viral pathogens.

antibody latches on pathogen


last case in somalia 1977

two viral strains exist, one in the US and one in Russia

Monkey pox

thought to be second coming of smallpox but caused by prairie dogs

Orthopoxvirus, variola virus= smallpox

enveloped DNA virus

immunity to smallpox= immunity to monkeypox

other members of the orthopoxvirus family:




smallpox portal of entry

1.mucous membranes in uper respiratory tract

2. droplet transmission (coughs and sneezes)

3. direct and indirect transmission ex. smallpox in blankets given to native americans

sequence of events in smallpox infections


entry via mucosal membranes of respiratory systems- then enters lymphoid tissue

sequence of events in smallpox infections

virus spread

Viremia and spread of virus in the RE(reticuloendothelial) system

the lymphatics

sequence of events in smallpox infections

multiplication in RE

multiplication of virus in the RE system, release of virus to blood

sequence of events in smallpox infections

more spread

secondary, more intense viremia, spread to tissue

sequence of events in smallpox infections

disease is full blown

clinical disease, development of lesions

two forms of smallpox

variola major 30% mortanilty

variola minor 1% mortality

smallpox infection type

smallpox is a primary infection- no matter how strong your immune system is, you will get sick

1-4 papular

1-4 also vesicular

2-6 pustular

2-4 weeks crusts fall off after first sign of lesion

Smallpox immunity:


vaccination with vaccinia virus provides immunity for at least 5 yrs

smallpox immunity:

neonates-newborn babies

protected via IgG from mother fro 2-3 months, then can be vaccinated

smallpox treatment: methisazone

only effective for prophylaxis

no effect for established disease

smallpox epidemiology

no asymptomatic carriers (no symptoms) or subclinical disease. sick but don't show symptoms or only mild ones

no non-human reservoir, no animals carried small pox

smallpox immunity

complete immunity after an infection

complications of smallpox

lesions become infected with secondary bacteria such as staphlycoccus aureus

can lead to bacteremia and sepsis, even death

difference between chickenpox and smallpox

chickenpox-lesions are in different stages

smallpox- all lesions are in the same stage of develeopment