1. Basics of HIV Virus Vijay Kandula, MD MPH AAHIVS
Adjunct Assistant Professor
Division of Public Health, Department of Family and Preventive Medicine
University of Utah, Salt Lake City
2013

2. Viruses are not living organisms
Viruses do not
Grow
Metabolize
Viruses do
Infect cells and use the host cell to make more copies of themselves
Cause disease in many organisms

3. Parts of a Virion (a virus particle)
Nucleic Acid – RNA or DNA
Capsid – protein coat that surrounds the DNA or RNA in a virus
Lipid Membrane – a membrane around the capsid in many kinds of viruses; helps the virus enter cells (“enveloped” viruses; without the membrane, the virus is “naked”)
Made of proteins, lipids, and glycoproteins

4. Mutating viruses
Viruses can mutate when they copy the genetic material
For e.g., a photocopy of document with stains; they show up in subsequent copies
Mistake proves useful
Can lead to stronger virus (more infectious)
Viruses don’t mutate often, except…
Influenza
HIV

5. Produces 1010-1012 new virions each day
HIV Replication
RNA Virus
Produces new virions each day

6. Basic Structure
Viral envelope: lipid layer; glycoproteins protrude from surface
Glycoproteins enable virus to recognize surface proteins of special CD4 or T Helper Cells (a special type of immune cells)
This allow entry into these cells (like a key to the cell’s door)
2 strands/copes of RNA
only 9 genes; 3 are found in many viruses (structural proteins)
Reverse Transcriptase enzyme
converts RNA into DNA (this makes HIV a RETROvirus);
This DNA instructs cell to make more viruses

7. The first step of infection is the binding of gp120 to the CD4 receptor of the cell, which is followed by penetration and uncoating.
The RNA genome is then reverse transcribed into a DNA provirus which is integrated into the cell genome.
This is followed by the synthesis and maturation of virus progeny.

8. HIV Replication 3D Medical Animation

9. Introduction Continued

10. Introduction Continued

11. Introduction Continued

12. HIV Types, Groups, and Subtypes
There are 3 HIV-1 genotypes; M (Main), O (Outlayer), and N (New) and P (New)
M group comprises of a large number subtypes and recombinant forms
Subtypes - (A, A2, B, C, D, F1, F2, G, H, J and K)
Recombinant forms - AE, AG, AB, DF, BC, CD
O, N and P group subtypes not clearly defined, especially since there are so few N and P group isolates.
As yet, different HIV-1 genotypes are not associated with different courses of disease nor response to antiviral therapy.
However, certain subgroups may be difficult to detect by certain commercial assays.

14. Geographic Distribution of HIV-1 Subtypes and HIV-2
A,B,A/B B B
HIV-2
C,E C
HIV-2 EB C
A,G,A/G
A,D
BFC C B
Subtypes A, B, C, D, “E”, F, G, H, “I”, J, K, CRFs, and untypable

15. HIV half-lives
Activated cells that become infected with HIV produce virus immediately and die within one to two days.
Production of virus by short-lived, activated cells accounts for the vast majority of virus present in the plasma.
The time required to complete a single HIV life-cycle is approximately 1.5 days.
Resting cells that become infected produce virus only after immune stimulation; these cells have a half-life of at least 5-6 months.
Such long-lived cell populations present a major challenge for anti-retroviral therapy.

16. HIV Origins

17. HIV Origins

18. HIV Evolution
Selection Pressure

19. HIV Evolution Types of selection pressure that effects HIV
Immune selection
Antiretroviral Treatment