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Introduction to HIV Virus

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On viral envelope are 72 spikes composed of proteins gp120 and gp 41 ... Translated at ribosomes to make new HIV proteins. Assembly ... – PowerPoint PPT presentation

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Title: Introduction to HIV Virus


1
Introduction to HIV Virus
2
What is HIV?
  • Human Immunodeficiency Virus
  • Composed of 9 genes
  • Bacteria typically have 5000 genes
  • Humans have 20,000-25,000 genes

3
Structure of HIV
  • 2 identical copies of single strands of RNA
  • Surrounded by viral Envelope of fatty material
  • On viral envelope are 72 spikes composed of
    proteins gp120 and gp 41

gpglycoprotein number is molecular weight
(daltons)
4
  • Beneath is a viral matrix composed of protein p17
  • RNA is surrounded by a capsid of protein p24

5
  • Also contains 3 enyzmes needed for HIV
    replication
  • Reverse transcriptase
  • Integrase
  • Protease

6
HIV Infection and Replication
7
Entry
  • HIV Spikes (Ligand) g120/41
  • Must Attach to at least two Receptors on Helper
    T-lymphocytes
  • CD4
  • 7-transmembrane receptor
  • HIV Ligand is the Key to Unlock the Receptor on
    the CD4 T cell

8
  • Releases contents into CD4 or Helper T-Cell

9
Reverse Transcription and Integration
  • HIV enzyme reverse transcriptase converts viral
    RNA to DNA
  • Makes copying errors
  • Leads to variations in HIV
  • New viral DNA is spliced into human DNA by HIV
    enzyme integrase

10
Transcription and Translation
  • Viral DNA lies dormant until T-cell is activated
  • Human DNA with viral DNA (provirus) now makes
    messenger RNA (human and viral)
  • Translated at ribosomes to make new HIV proteins

11
Assembly
  • New long Viral polypeptide chain is chopped up
    into smaller pieces by protease
  • Creating new enzymes and viral coat proteins

12
Budding and Maturation
  • Assembles all viral components
  • Buds from host cell
  • Takes a piece of the host plasma membrane

13
Effect on Immune System
  • Activates Helper T-Cell The General
  • Secretes Cytokines which ……
  • Activate macrophages, cytotoxic or killer
    T-cells, and natural killer cells
  • Control maturation and induction of
    antibody-producing B cells
  • Secrete colony stimulating factors for more white
    blood cells

14
1st Stage of Infection - Primary
  • Rapid viral replication
  • Patient exhibits flu-like symptoms
  • Undergoing Seroconversion
  • B-cells making antibodies
  • Patient is infectious but will not test for
    HIV

15
2nd Stage of Infection- Clinical Latency
  • Strong immune defense to that particular variant
    of HIV
  • Reduced number of viruses
  • Lasts 2 weeks -20 years
  • Patient still infectious
  • Will test for HIV

16
3rd Stage of Infection AIDS
  • Virus has mutated
  • T-cells and B-cells are activating against all
    the different variants of HIV
  • Helper T-cells are dying
  • Bone marrow cant make new cells fast enough
  • Immune System is overloaded and compromised

17
  • Normal count 800-1200 cells/ul
  • If CD4 T cell count drops below 200 cells /ul
  • patient has AIDS
  • patient is susceptible to opportunistic
    infections.

18
Types of Drugs Used on HIV
  • Reverse Transcriptase Inhibitors
  • AZT blocks recoding of viral RNA into DNA
  • Protease Inhibitors
  • Blocks protease that cleaves viral polypeptide
    into functional enzymes
  • Best regimen is cocktail of both types of drugs

19
The End
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