Viruses
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Are Viruses Living Things? ____________ Why? _____________________________________________________________
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Viruses, ___________________________________________________________________________ can all cause infection.
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Viruses are named for _________________________________________________________________________________
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______________________________________________________________ can all cause infection.
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Any disease-causing agent is called a _____________________________.
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A virus is made __________________________________________________________________________.
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A viroid is made only of ___________________________________________________________________.
causes _________________________
passed through ___________________
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A prion is made only ____________________________________.
causes misfolding ___________________________
results in diseases ___________________________
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How viruses enter our cells
The virus has an ___________________ that mimics a body cell
The antigen will fit in a cells ___________________________
The cell allows the viral DNA to enter the cell
A virus is ____________________ as to what type of cell it infects
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Viruses have a simple structure.
____________________ (DNA or RNA)
____________________, a protein shell
maybe a lipid envelope, a protective outer coat
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Once a virus enters a host cell, two different processes can occur:
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2.
Lysogenic cycle
Lytic cycle
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Lytic Cycle
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viral DNA is injected into the host cell
host cell begins to make ______________ from the _________________________
_________________________________ shut down the host cell’s regular functions
cell is used to make _______________________________ (DNA and protein coats)
host cell bursts (lyses) and releases viruses to infect other cells
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When a Lytic Virus infects a cell, an immune response will ________________________________
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Lysogenic Cycle
1.
2.
3.
4.
viral DNA is injected into the host cell
viral DNA is __________________ into the host ___________________
host cell divides with the ____________________ as a part of it
eventually the viral DNA can be triggered to separate from the host cell DNA and pick up with the lytic cycle at step 2.
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A lysogenic infection does no immediate harm
Example: Herpes (warts)
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Viruses cause many ________________________________________________________
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There are many examples of viral infections.
 common cold, influenza
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RNA viruses do not have built in proofreading, so they ____________________________________________ (like the flu).
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A special kind of RNA virus, called a ________________________________, can cause DNA to be made from their RNA.
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Certain cancers, and AIDS are caused by retroviruses.
Some viral diseases can be prevented with ________________________________
Vaccines are made from _________________________________________________
A vaccine stimulates the body’s _____________________________________________________________________.
Vaccines prepare the immune system for a ____________________________________________________________
Common Cold
Causes: _________________ viruses can cause it, including rhinoviruses
No evidence for weather causing a cold
Symptoms:
Runny nose, sore throat, headache, cough
Treatment:
_____________________________ decongestants & glycerin based cough suppressants
NSAIDS (ibuprofen)
Transmission:
Inhaling drops of mucus full of rhinovirus
Touching contaminated surfaces
Influenza “the flu”
Cause: ______________________________________
Symptoms:
Fever, headache, fatigue, body aches, congestion
Treatment:
CDC currently recommends ___________________________________ for flu due to growing virus resistance.
Transmission:
Inhaling drops of mucus full of influenza virus
Touching contaminated surfaces
Status:
Vaccines present, BUT it changes yearly (RNA virus)
Threat of flu pandemics worldwide
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Smallpox
Cause: __________________________
Symptoms:
High fever, body aches, small raised bumps all over body
Treatment:
____________________________________________________
Most recover, 30% mortality
Transmission:
inhaling droplets of affected saliva
face-to-face contact with an infected person
Status:
Vaccine present
Can be fatal
Eradicated worldwide, last naturally occurring in 1977
Herpes Simplex I
Cause: ____________________________________
Symptoms: _____________________________________
Treatment:
Topical medication to reduce outbreaks
Antiviral medication to reduce number of outbreaks
Transmission:
Kissing, eating/drinking after one another
Status:
No vaccine, no cure!
Herpes Simplex II
Cause: (HSV-2)
Herpes Simplex Virus Type 2
Symptoms:
Pain, itching, blisters on genitals, anus and thighs
Treatment:
medication to reduce symptoms and reduce number of outbreaks
Transmission:
Sexually transmitted, may not be showing signs, oral or vaginal sex
Status:
No vaccination, no cure!
1 out of 5 adolescents and adults have had HSV-2 in the US!
Human Papillomavirus (HPV-warts)
Cause: _________________________________________________________
Symptoms:
Raised or flat, single or multiple swellings on any genital surface, male or female, can appear cauliflower-like
Can cause _______________________________________ in women
No visible signs may occur
Treatment:
Topical creams are available, doctors may freeze or burn them off
May remove warts but virus is still present in the body and warts may return
Transmission:
Very contagious
sexual contact with infected partner, may not be showing signs
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Status:
No cure!
Tests available for presence in women
_______________________________- new vaccine that prevents the 4 highest risk strains of HPV
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HIV (Human Immunodeficiency Virus)
The HIV virus infects cells of the immune system called ___________________________________________
a. Normally Helper T cells activate cells that produce antibodies and cells that destroy cells infected by a pathogen.
b. When a Helper T cell is infected by the HIV virus, the immune system cannot fight off infections from pathogens
such as bacteria and other viruses.
c. HIV can cause _____________________________________________________ when enough Helper T cells are
infected so the immune system does not work properly.
d. People with HIV infections can get sick easily because their immune system does not work properly. People with
AIDS do not die from the HIV virus, but from _____________________________________________________
Cause:
Human Immunodeficiency Virus
Symptoms:
Fever, headache, tiredness, enlarged lymph nodes
AIDS (Acquired Immunodeficiency Syndrome)
weight loss, fatigue, memory loss
Destroys Helper T cells (part of immune system)
body cannot fight off illnesses caused by bacteria, other viruses, fungi, or parasites.
Ultimately leads to death
Treatment:
Reverse Transcriptase (RT) inhibitors & Protease Inhibitors- stops the virus from making copies of itself
Transmission:
sexually (orally, vaginally)
Blood (needles, or through mucus membranes)
Breast milk mother to child
NOT from kissing, touching, insects bites
Status:
 No vaccine, several medicines to prevent spread in body
 Worldwide: In 2004, 40 million people living with HIV/AIDS, 5 million newly infected, and 3.1 million deaths
Ebola Hemorrhagic Fever
Cause:
1 of 4 Ebola viruses
Symptoms:
Fever, headache, muscle/joint pain, red eyes, skin rash
Diarrhea, vomiting, rash, internal and external bleeding
Treatment:
No standard treatment
Some patients recover but majority die, usually because the lack of immune response
Transmission:
Contaminated body fluids: Blood, mucus, semen, syringes
Air transmission in monkey Ebola-Reston virus only
Status:
 Only identified in 1976 with few devastating outbreaks
 RNA virus