L19- HIV Infection and AIDS Part 2

Question 1

Describe characteristics of human immunodeficiency virus (HIV)

Answer 1

Genus Lentivirus
Retrovirus
Single stranded
Positive sense
Enveloped (P24 capsid)
RNA  
Reverse transcriptase
Protease 
Integrate
p17 matrix
gp41
gp120 (binds to CD4)
Lipid bilayer

Question 2

What are the differences between HIV1 and HIV2?

Answer 2

HIV1:
Virulence: High
Infectivity: High
Prevalence: Global
Origin: Chimpanzee

HIV2:
Virulence: Lower
Infectivity: Low
Prevalence: West Africa
Origin: Sooty mangabey

Question 3

How is HIV infection transmitted?

Answer 3

•  Sexual transmission

–  Vaginal
–  Rectal

•  Injection of infected blood or blood products

–  Intravenous drug use

•   Mother to child transmission
•   Others

Question 4

How does HIV infect cells of the immune system?

Answer 4

Via CD4 T cells and CCR5 or CXCR4

Question 5

Describe how HIV infects the immune system during an early (acute) infection

Answer 5

Memory CD4 T cells (CCR5+), particularly in GALT causing massive CD4+ T cell depletion

Question 6

Describe how HIV infected the immune system during a chronic infection

Answer 6

Macrophages/monocytes, DCs and CD4+ T cells causing immune activation and inflammation in lymphoid tissues

Question 7

How does HIV infection affect the thymus?

Answer 7

Decreased production of naive T cells

Question 8

How does HIV infection affect the lymph nodes?

Answer 8

Impaired homeostatic proliferation and function of CD4 and CD8 memory T cells

Germinal centre dysfunction, including decreased production of memory B cells

Question 9

What affect does HIV infection have on the spleen?

Answer 9

Decreased production of IgM memory B cells

Question 10

What affect does HIV infection have on GALT?

Answer 10

Increased translocation of microbial products into the blood, which contributes to activation of monocytes and macrophages and inflammation.

Question 11

Monkeys with simian immunodeficiency virus (SIV) infection have a different susceptibility to AIDS.

*(Between Rhesus macaque
African green monkey)

Answer 11

SIV-infected African green monkeys (AGMs) avoid AIDS

Question 12

Name some pathogens causing disease as a result of HIV induced immunodeficiency .

Answer 12

•  Fungi/yeasts
•  ‘Persistent viruses’
•  Mycobacteria
•  ‘Intracellular bacteria’
•  Protozoans
•  Streptococcus pneumoniae

Question 13

Describe the affects of fungi causing disease in HIV-induced immunodeficiency

Answer 13

•  Mucocutaneous

–  Candida (mouth, oesophagus)
–  Dermatophyte infections of skin

•  Systemic

–  Pneumocystis jirovecii (lungs)
–  Cryptococcus sp. (lungs and brain)
–  Aspergillus sp.
–  Histoplasma
–  Coccidioides sp.
–  Blastomyces sp.
–  Talaromyces marneffei

Question 14

List some persistent viruses causing disease in HIV-induced immunodeficiency

Answer 14

•  Herpesviruses
–  Cytomegalovirus
–  Epstein Barr virus
–  Herpes simplex virus
–  Varicella zoster virus
–  Human herpes virus-8

•   Hep C and B virus
•   Human papillomavirus
•   JC polyomavirus
•   Molluscum contagiosum virus

Question 15

List some mycobacteria causing disease in HIV-induced immunodeficiency

Answer 15

•  Mycobacterium tuberculosis

•  Non-tuberculous mycobacteria
–  Mycobacterium avium complex (MAC)
–  Mycobacterium leprae
–  Other non-tuberculous mycobacteria

Question 16

List some protozoans causing disease in HIV-induced immunodeficiency

Answer 16

•   Toxoplasma gondii
•   Cryptosporidium
•   Microsporidium
•   Giardia
•   Isospora

Question 17

AIDS-associated malignancies associated with virus infection:

Kaposi sarcoma is caused by which virus?

Answer 17

HHV-8

Question 18

AIDS-associated malignancies associated with virus infection:

• Lymphoma
• Primary cerebral lymphoma
• Smooth muscle tumours

Answer 18

EBV

Question 19

AIDS-associated malignancies associated with virus infection:

Carcinoma of cervix/ anus

Answer 19

HPV

Question 20

HIV can also cause neurological disease. Name an example.

Answer 20

HIV encephalopathy