HIV

Question 1

What type of virus is HIV?

Answer 1

Retrovirus (copies RNA to DNA to integrate into host genome)

Question 2

Characteristic of retrovirus?

Answer 2

• enveloped
• 2 copies of ss RNA

Question 3

What are the 2 genotypes of HIV viruses?

Answer 3

HIV-1 (rest of world) (jumped from chimps to humans)
HIV-2(Western Africa) (Close to mandrill virus

Question 4

Key structural parts for HIV

Answer 4

Gp120 (outer envelope glycoprotein)
Gp41 (embedded in envelope)
P24 (capsid protein)
Reverse Transcriptase
Integrase
Protease

Question 5

When can antibodies for HIV be found?

Answer 5

AIDS, Pre-AIDS, Risk Groups

Question 6

When can HIV virus be isolated?

Answer 6

AIDS, Pre-AIDS, Risk Groups

Question 7

What are the 4 Koch’s Postulates?

Answer 7

1. The microorganism must be found in abundance in all organisms suffering from the disease but should not be found in healthy organisms.
2. The microorganism must be isolated from a diseased organism and grown in pure culture.
3. The cultured microorganism should cause disease when introduced into a healthy organism.
4. The microorganism must be re-isolated from the inoculated, diseased experimental host and identified as being identical to the original specific causative agent.

Question 8

Briefly describe process of infection by HIV

Answer 8

1. Attachment, Entry & Uncoating - GP120, CD4 Receptor Site
2. Reverse Transcriptase & Integration
3. Synthesis of Viral Parts
4. Assembly and Release
   - protease to cleave protein into functional parts

Question 9

Draw a graph showing the levels of
a) GP120 antibody
b) p24 antigen (viral load)
c) CD4 T cells

Question 10

Draw a graph showing the levels of
a) p24 antigen
b) IgM
c) p24 antibody
d) IgG

Question 11

Describe the progression of HIV.

Answer 11

1. Primary Infection (weeks)
   - burst of viraemia
   - transient decrease in CD4
2. Latency (years)
   - Immune System fights off virus
   - chronic low level viraemia
   - CD4 depleting slowly
3. Progression to AIDS
   - CD4 cell loss outweighs production
   - Below 200 cells/mm3

Question 12

Detection of HIV?

Answer 12

1. PCR
2. Culture
   *not rly used bc expensive and time consuming
3. ELISA (first line)
4. Western Blot (confirmatory after +ve ELISA) – presence of bands at p24, p31, gp41, gp120, gp160
5. Combination Assays
6. Assays for HIV ab without invasive sampling (use saliva/urine samples) (oraquick rapid HIV)

Question 13

Clinical PResentation of HIV

Answer 13

1. Lab Evidence - <200cells/mm3 CD4
2. condition indicative of immunodeficiency
   - Kaposi Sarcoma
   - P. jirovecii
   - Mycobacterium avium
   - lymphoma
   - cervical cancer
3. Cachexia

Question 14

How might Kaposi Sarcoma and P. Jirovecii present?

Answer 14

Pink flat indurated lesion, gradually becomes darker and more widespread

Oral lesions (oral candidiasis, oral thrush [can be scraped, white]

*common in diabetes, pt on steroids, cancer

Question 15

Stopping Transmission of HIV

Answer 15

1. few partners
2. condom use
3. advice to sero +ve women
4. no sharing needles
5. no IV drug use

rmb vaginal route > anal route