Virsuses:Human Immunodeficiency Syndrome

& Acquired Immunodeficiency

Syndrome

Outline• Introductory Comments

– Virus versus bacteria– Examples of DNA and RNA containing viruses– How RNA containing viruses can replicate

• Origins of HIV– Dr. Hahn and colleagues

• Characteristics of HIV Particle– Glycoproteins– Viral genes

• Laboratory Diagnostic Tests– PCR– Western Blot– ELISA

• -------------------------------------------------- Part 2 -------------------------• Treatment• Transmission• Prevention

Bacteria versus Viruses

Note: These STDs are bacterial infections!

• SYPHILIS– Bacterium: Treponema pallidum

• GONORRHEA– Bacterium: Neisseria gonorrhoeae

Viruses

• DNA containing

• RNA containing

DNA containing viruses

• Herpes virus

• Small pox virus

• Hepatitis B

• adenovirus

RNA containing viruses

• Hepatitis A and C• Rabies• Ebola• Measles • Mumps• Polio• HIV

Rabies virus

Measles on the back

HIV

Examples of how RNA viruses replicate

Negative strand

Positive strand

Retro

RETROVIRAL REPLICATION

HUMAN IMMUNODEFICIECY VIRUS

• Family: retrovirus• Genus: lentivirus• Species: HIV 1 and HIV 2• Groups and Subtypes: variety

“Predominant Subtypes of Group M”

• Africa• Americas• China (southeast)• Europe• India• Japan• Thailand

• A;D;C• B• C• B• C• B• E

Dr. Beatrice Hahn & colleagues:Drs. Li and Keele

Greater spot nose monkey Red Cap Mangabey monkey

SIV cpz almost identical to HIV 1

Humans

Pan troglodytes troglodytes

Simian Virus (SIV cpz) almost identical to HIV 1

Sooty mangabey monkey

Simian Virus corresponds to HIV2

HIV: Structure and mechanism of replication

HIV-1 PARTICLE

HIV Glycoproteins

• Lipid Bilayer contains glycoproteins

– Gp 160– Gp 120– Gp 41

T lymphocyte in green and HIV in red

HIV and helper T cells

HIV-1

HOST CELLS: helper T lymphocyte, macrophages

http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter24/animation__hiv_replication.html

Budding of HIV from T lymphocyte

HIV

HIV

Mechanism of Infection

VIRAL RNA

PROVIRAL DNA

Infects Th cell

Integrates into host DNA

“activated”LYTIC STAGE storage

LYSOGENIC STAGE

Co-Receptors

CCR5 or CXCR4 (fusin)

Binds naturally occurring chemokines

LYTIC STAGE

The key HIV genes

HIV Diagnostic Tests

• Western Blot

• PCR Directly measures HIV

Polymerase Chain Reaction• Measures proviral DNA within the host DNA

Western BlotIdentifies HIV proteins

Protein ladder

HIV Diagnostic Tests

• ELISA

Indirect evidence of HIV exposure

measures

• A diagnostic test for Antibodies to HIV

Enzyme Linked Immunosorbent Assay

(ELISA)

Antibodies

*Antibodies are proteins produced by our immune system that are

directed against specific antigens.

(Antibody interactions with antigens will also be discussed in our “immungenetics lecture”)

Antibodies Antigens

Immune system Non-self

Now apply these concepts to the diagnostic test known as ELISA to detect antibodies against HIV from a biologic

fluid.

Do any of these individuals carry antibodies to HIV?

ELISA MICROTITER PLATES

Microtiter plate

The ELISA protocol

12

3

4

antigen

sampleLabelled 2nd Ab

Color inducing substrate

Results

POSITIVE ANTI-HIVCOLOR CHANGE

NEGATIVE ANTI-HIVNO COLOR CHANGE

FDA Approves Saliva OraQuick Rapid Test for HIV-1, HIV-2

Antibodies[March 29, 2004]

(similar test is also available for blood samples, see next slides).

OraQuick Rapid Anti-HIV Blood Test

1 2

3 20 minute testCost app. $15.00

Outline• Introductory Comments

– Virus versus bacteria– Examples of DNA and RNA containing viruses– How RNA containing viruses can replicate

• Origins of HIV– Dr. Hahn and colleagues

• Characteristics of HIV Particle– Glycoproteins– Viral genes

• Laboratory Diagnostic Tests– PCR– Western Blot– ELISA

• -------------------------------------------------- Part 2 -------------------------• Treatment• Transmission• Prevention