25 - HIV and AIDS

Question 1

End stage disease caused by HIV

Answer 1

AIDS

Question 2

Original name for HIV

Answer 2

Lymphadenopathy associated virus (LAV), then Aids associated retrovirus (ARV)

Question 3

Three different stages in the formation and
maturation of HIV

Answer 3

• Polyprotein precursor
• Immature virion
• Structural rearrangement of the processed proteins in the mature virion

Question 4

HIV genome and virion

Answer 4

• Enveloped
• +ssRNA with DNA intermediate
• Replicates using RdDp (RT)
• 2 copies of ssRNA codes for structural, regulatory, and accessory proteins

Question 5

HIV structural proteins

Answer 5

Gag, Pol, Env

Question 6

HIV regulatory proteins

Answer 6

Tat and Rev

Question 7

HIV accessory proteins

Answer 7

Vpu, Vpr, Vif and Nef

Question 8

Entry of HIV

Answer 8

Occurs largely across mucosal surfaces

Question 9

Cells susceptible to HIV

Answer 9

Myeloid DCs, Plasmacytoid DCs, and Langerhans cells

Question 10

DCs

Answer 10

Express high levels of C-type lectins, including DC-specific intercellular adhesion molecule 3 (ICAM3)-grabbing non-integrin (DC-SIGN)

Question 11

DC-SIGN

Answer 11

• Glycoproteins
• Main HIV attachment factors at the surface of dermal and mucosal DCs

Question 12

HIV Transmission

Answer 12

Can occur across the infectious synapse, exocytic pathway and de novo virus production

Question 13

R5 variants

Answer 13

• Make up the majority of transmitted and founder viruses
• Predominates in the blood prior to the development of AIDS

Question 14

T cell tropic strain of HIV

Answer 14

• X4
• Bind CXCR4

Question 15

Macrophage tropic strain of HIV

Answer 15

• HIV R5
• Bind CCR5

Question 16

Eclipse phase

Answer 16

• Infection of first cells
• Systemic spread via lymph
• IFN response

Question 17

Acute phase

Answer 17

• First detection in blood
• Flu like symptoms
• CTL response
• Seroconversion

Question 18

Chronic phase

Answer 18

• Viral set point established
• Progressive CD4 T cell loss
• Chronic inflammation
• Progression to AIDS

Question 19

Higher set point

Answer 19

• More fit virus
• CTL escape
• HIgh levels of inflammation

Question 20

Lower set point

Answer 20

• Poorly fit virus
• Strong IR
• Low levels of inflammation

Question 21

AIDS

Answer 21

Presence of HIV infection and either a CD4+ T cell count of <200 cells per μl or an AIDS-defining complication

Question 22

Effects of HIV-1 infection on lymphoid tissue

Answer 22

• Progressive damage to lymph node germinal centres
• Connective tissue replaces much of the normal cell population
• End result is increased viremia and decreased immune capacity

Question 23

AIDS defining conditions

Answer 23

• Candidiasis of bronchi, trachea, lungs
• Cytomegalovirus disease
• Kaposi’s sarcoma
• TB
• Pneumocystis jirovecii pneumonia
• Toxoplasmosis of brain

Question 24

Main classes of antiretroviral drugs

Answer 24

• Fusion inhibitors
• Entry inhibitors
• RT inhibitors (Nucleoside and non-nucleoside)
• Integrase inhibitors
• Protease inhibitors

Question 25

HIV vaccine

Answer 25

• T cell mediated response
• Neutralising antibody response: Induce antibodies that block HIV in the blood, preventing HIV from infecting the body͛s cells.
• Non-neutralising antibody response: Induce antibodies that recognise HIV and recruit other immune cells to help destroy the virus.
• Combination responses

Question 26

HIV prevention strategies

Answer 26

• Pre and post exposure prophylaxis
• Condom use
• Neutralising antibodies
• Male circumcision
• Vaccines

Question 27

HIV persistance

Answer 27

• Throughout deep tissues with repopulation from multiple anatomical sources
• Blood is main source of dispersal

Question 28

Requirements for protective immunity against HIV-1

Answer 28

• CD4 and CD8 T cells
• Innate immune responses
• NK CElls
• ADCC
• Neutralising antibodies