Transcript Document
Antivirals
Structure of a Virus
• all viruseso have a central core of DNA or RNA
o surrounded by a coat(capsid) of packed protein
units(capsomers)
• UNLIKE bacteria- viruses have no nucleus or cytoplasm
o therefore, they are not cells
o do not feed,
excrete, or grow
o can only reproduce inside
the cells of living
organisms using the host
cell
Multiplication of Viruses
• can survive outside the host cell
• can only replicate by:
o penetrating the living host cell
o then injecting their DNA or RNA into the cell's
cytoplasm(part of the cell enclosed within the cell
membrane).
o the virus then takes over the biochemical machinery
o causes the host cell to become altered or die, leads to
symptoms of a viral infection.
• produces new DNA or RNA and forms large numbers of the
viruses
o then released to infect other healthy cells
Antiviral Drugs
• Viral Infections:
o cold, influenza, mumps, chicken pox
• Body's defense mechanisms are usually strong enough to
fight the infections, drugs are given to remove pain, fight
fever, or stop a second infection.
o Difficulties:
viruses multiply fast
by the time the symptoms appear, there are too many
viruses and the antiviral drugs will have little effect
• problem with inventing new antiviral drugs: they are
always mutating themselves
HIV
Antiviral Drugs cont.
• drugs have been developed to fight specific infections
• Alters the cell's genetic material- virus can't use it then to
multiply
o Acyclovir: used to treat cold sores caused by herpes
structurally similar to deoxyguanosine(a building
block of DNA)
viral enzymes are tricked into using it as a building
block for the viral DNA and prevents spreading
• Prevent the new viruses formed from leaving the cell
o Amantadine: used against the influenza virus
enzyme used by influenza virus to stick to the host
cell wall as it leaves is called neuraminidase
works by inhibiting the active site on this enzyme
AIDS(Acquired Immune Deficiency
Syndrome)
• no cure for AIDS
• drugs that slow dow the HIV virus and damage to your immune
system
• AIDS is the most advance stage of HIV
• HIV is a virus that kills or damages the cells of the body's immune
system
AIDS: What is it?
• Cause by a retroviruso it contains RNA instead of DNA
• virus invades cells, particularly white blood cells(normally
activate other cells in the immune system)
o the body is then left helpless to fight the infection
AIDS: What happens?
• the virus invades a healthy cell
• makes viral DNA from the RNA template using an enzyme
called reverse transcriptase
• this process is OPPOSITE of the process that takes place in
healthy cells
o i.e.: RNA is made from DNA template using the
transcriptase enzyme
Drugs that help fight AIDS
• AZT(zidovudine)
o combines with the enzyme that the HIV virus uses to
build DNA from RNA and clogs it active site
o reverse-transcriptase inhibitor
instead of changing RNA to DNA it clogs the active site
so that the virus can't create viral DNA
o only retroviruses use the enzyme AZT, does not affect
healthy cells
an RNA virus that is replicated in a host cell via the enzyme reverse
transcriptase to produce DNA from its RNA genome.
Sources:
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http://www.nlm.nih.gov/medlineplus/aids.html
http://en.wikipedia.org/wiki/Retrovirus
http://www.drugs.com/pro/amantadine.html
http://www.avert.org/aids.htm
http://www.drugs.com/acyclovir.html
http://en.wikipedia.org/wiki/AIDS#Treatment
http://www.aids.gov/
http://www.aids.org/factSheets/101-What-is-AIDS.html
http://en.wikipedia.org/wiki/Cytoplasm