Viruses, HIV, & AIDS

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Viruses, HIV, AIDS
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Virus Introduction
Viruses are not living things
Traits of Living Things
Viruses consist of nucleic acids proteins.

• Living things consist of cells
• Cells are made up of complex compounds proteins,
  lipids, carbohydrates, nucleic acids
• Living things reproduce
• Living things grow develop
• Living things convert energy carry out
  metabolism

Viruses replicate, but need a host cell in order
to do so.
Viruses dont grow, develop, or carry out
respiration Viruses are not cells (no membrane
or cytoplasm)
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Viral Structure
Viruses may have spikes
Viruses have a protein coat called a capsid
Viruses may have an envelope that consists of
part of cell membranes
The capsid encases nucleic acid (DNA or RNA)
Viruses are very small (lt 1mm)
Adenoid Virus
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Viral Replication
A Virus Must Enter a Host Cell to Replicate
Virus binds to membrane of host cell
1. Attachment
Virus injects its nucleic acid into the host cell
2. Entry
Host cell makes viral DNA viral proteins
3. Replication
New viruses assembled from proteins nucleic
acids
4. Assembly
Host cell releases new viruses
5. Release
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Viral Diseases
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Polio Virus
Rotavirus
Ebola Virus
Hepatitis B Virus
Rabies Virus
Herpes Virus
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Influenza Virus
Tobacco Mosaic Virus
Small Pox Virus
Adenoid Virus
Pneumovirus
Bacteriophage
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Are Viruses Living?
No, viruses are technically not considered living
things.
Why?

• Viruses do not carryout metabolic reactions like
  respiration or photosynthesis. They dont
  convert energy

• Viruses are unable to reproduce or replicate on
  their own

And Most Importantly...
VIRUSES ARE NOT CELLSTHEY DO NOT HAVE A MEMBRANE
CYTOPLASM
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What Is a Virus?

• Viruses are non-living particles that consist of
  fragments of cells (protein nucleic acid)

• Viruses are less than 1 mm in size

• Viruses are able to replicate, but need to do so
  in a host cell

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HIV AIDS
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HIV Basics
HIV stands for Human Immunodificiency Virus
HIV is a Retrovirus
HIV targets white blood cells
HIV infection results in AIDS
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Retroviruses
Contain RNA for a nucleic acid
Revearse Transcriptase Enzyme produces DNA from
RNA
DNA integrated in host cell's DNA
Viral RNA
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HIV Structure
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HIV Replication
HIV Binds to Immune Cells gp 120 locks to
cells CD4 protein
Attachment

• HIV injects RNA into CD4 cell.
• Reverse transcriptase produces DNA from RNA.
• Viral DNA embeds in cells DNA in nucleus

Entry
Cells DNA Produces viral RNA and proteins
Replication
Viral proteins RNA assemble into new virus at
the membrane
Assembly
Virus buds at membrane. Part of CD4 cell
membrane becomes viral envelop.
Release
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HIV infects cells that have CD4 Proteins
CD4 Cells Include...
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Disorders of the Immune System AIDS
Acquired Immune Deficiency Syndrome
When the immune system is lacking one or more of
its components, the result is an immunodeficiency
disorder.
AIDS is an immunodeficiency disorder caused by a
virus that destroys helper T cells and that is
harbored in macrophages as well as helper (T4) T
cells.
The AIDS virus splices its DNA into the DNA of
the cell it infects the cell is thereafter
directed to churn out new viruses.
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Progression of AIDS
HIV infects the vulnerable CD4 cells and
replicates at a high rate within these cells. As
the number of infected cells increases, the
destruction of the immune system progresses.
The rate of viral replication in productively
infected CD4 cells is extremely high (one billion
viral particles are produced every day).
 
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Progression of AIDS
The immune system controls the infection by
producing vast numbers of T helper cells.
The battle between the viral infection and the
cells of the immune system continues.
Eventually the virus' ability to damage the
immune system exceeds the body's capacity to
fight HIV.
Normal Immunity
Onset of AIDS
500 - 1500 CD4 Cells per mm3 of Blood
lt 200 CD4 Cells per mm3 of Blood
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HIV / AIDS Summary
AIDS is caused by HIV infection
HIV is a retrovirus
HIV infects helper T cells (CD4 cells)
HIV infection compromises the immune response
AIDS results in death