Lecture 13

Question 1

There is a decline in infection from 2001 as a result of

Answer 1

anti-retroviral therapy - reduces infectiveness

Question 2

Circumcision protects men from HIV by about __%

Answer 2

70%

Question 3

HIV is part of the retroviral family of _________

Answer 3

Lentiviridae, meaning they cause infection slowly

Question 4

SIV is

did HIV arise from it?

Answer 4

Simmian Immunodeficiency virus

HIV arise from these monkey viruses

Question 5

The slaughtering of monkeys in africa likely lead to the ______ of HIV variants into humans in the 1930s

Answer 5

Zoonoses

Question 6

SIV, HIV1/2 all have regulatory proteins __, __, ___

But differ in the variable regions of regulatory proteins

Answer 6

SIV, HIV1/2 all have regulatory proteins gag, pol, env

But differ in the variable regulatory proteins

Question 7

There are _ single strands of RNA in the HIV virus

Answer 7

2

Question 8

Env = gp 120 and …

Answer 8

gp120 (Surface; cell attachments) and

gp 41 (Transmembrane fusion domain)

Question 9

gag consists of

structural proteins

Answer 9

• p17 (MA - Matrix)
• p24 (CA-capsid)
• p7 (Nucleocapsid)

Question 10

pol consists of

Answer 10

p66/51 (RT-reverse transcriptase)

p32(IN- integrase)

p11 (PR - protease)

Question 11

clades are seperated by their…

Answer 11

genetic diversity

Question 12

HIV -1 M groups sits close to….

Answer 12

SIV CPZ

Question 13

gp120 binds to ____

Answer 13

CD4

Question 14

Once it binds, the envelope undergoes a conformational changes and binds a second time to _____ and _____

Answer 14

Once it binds, the envelope undergoes a conformational changes and binds a second time to CCR5 or CXCR4 co receptors

Question 15

Upon entering the cell, the RNA undergoes _____ _______

Answer 15

reverse transcription

makes pro-viral DNA and integrates to the host DNA

Question 16

what are the key features for HIV replication?

Answer 16

Rapid

Error prone reverse transcriptase leads to rapid evolution of multiple quasispecies

10 billion particules produced per day

Question 17

If Virus enters an activated CD4+ cell - it is..

If resting…

Answer 17

killed

If resting - latency

Question 18

True or False

HIV can only affect Cd4+ T cells

Answer 18

False

Can also infect Monocyte/macrophages

Question 19

Viruses that use CCR5 are called

Answer 19

R5 viruses (95%)

Question 20

Viruses that use CXCR4are called

Answer 20

X4 viruses

Question 21

R5 viruses cause ___ T-cell destruction

Answer 21

less

Question 22

50% of patients with AIDS carry an __ virus

Answer 22

X4 virus (develops later on)

Question 23

If you are homozygous for CCR5, you are only exposed to rare infection with ___

Answer 23

X4

Question 24

True or False

CCR5 is not neccessary for immune function

Answer 24

True

Question 25

True or false

HIV can enter Dendritic, Thymocytes and CD34+ progenitor cells

Answer 25

true

Question 26

What is the normal role of APOBEC3G?

Which HIV protein blocks it?

Answer 26

Sees foreign RNA and edits so it doesn’t persist in the cell.

Blocked by vif (HIV protein)

Question 27

What is the normal role of Trim 5 alpha?

Which HIV protein blocks it?

Answer 27

Blocks uncoating of retroviruses

Blocked by capsid

Question 28

What is the normal role of Tetherin?

Which HIV protein blocks it?

Answer 28

Blocks release of virus

blocked by vpu

Question 29

What is the normal role of LEDGF?

Which HIV protein facilitates integration?

Answer 29

Tethes HIV to host chromatic

Integrated by Integrase

Question 30

How does HIV evade the immune response?

Answer 30

Sequence variation - Lack of recognition

Altered antigen presentation - down regulation of MHC class I molecules by Tat, Vpu and Nef

Loss of effector cells - Clonal exhaustion, loss of CD4 Tcell help, Replicative senescence

Latency - silent, evades response

Priveleged sites of viral replication - BB barrier etc…