SLIDE 1
HIV-1 protease
- Essential for the production of infectious HIV-1 particles
- Responsible for the ordered cleavage of two precursor proteins
HIV can modulate Gag NC/p1 cleavage and thereby affect PI - - PowerPoint PPT Presentation
HIV can modulate Gag NC/p1 cleavage and thereby affect PI - - PowerPoint PPT Presentation
HIV can modulate Gag NC/p1 cleavage and thereby affect PI susceptibility and viral replicative capacity Monique Nijhuis HIV-1 protease Essential for the production of infectious HIV-1 particles Responsible for the ordered cleavage of
SLIDE 2
SLIDE 3
HIV-1 protease: ordered gag cleavage
SLIDE 4
HIV-1 protease inhibitor resistance
Two protease inhibitor resistance mechanisms:
- 1. Mutations in the viral protease itself
Reduce affinity of the viral protease for the inhibitor
- 2. Mutations in the substrate of the viral protease (NC/p1 CS)
Enhanced substrate cleavage
SLIDE 5
Gag NC/p1 substrate based PI resistance
Nijhuis et al, PLOS Medicine 2007
Gag Gag
p2 p2 MA CA p24 p24 p17 p17 NC p1 p1 p7 p7 p6 TFP INT RT PR
Pol Pol
428 E
- 429
R
- 430
Q
- 431
A V
- 432
N
- 433
F
- 434
L
- 435
G
- 436
K
- E
437 I
- V
T T 431V 437V 437T 436E+437T
NC NC p1 p1
SLIDE 6
NC NC p6 p6 NC NC
- Conc. RO033-4649
(nM)
Increased NC/p1 cleavage of mutant
increase in overall Gag cleavage (CA/MA-antibody)
SLIDE 7
Nijhuis et al, PLOS Medicine 2007
Phenotypic susceptibility of NC/p1 mutants
- why don’t we see these NC/p1 CS changes that often?
SLIDE 8
Effect of NC/p1 changes on viral replicative capacity
100 1000 10000 100000 1000000 10000000 1 2 3 4 5 6 7 9 10 13 Days pg p24/ml HXB2 431V 437V 437T 436E+437T
- reduced replication capacity be repaired?
SLIDE 9
Three evolutionary pathways for the double NC/p1 mutant
NC p1
428 429 430 431 432 433 434 435 436 437
E R Q A N F L G K I HXB2 GAG AGA CAG GCT AAT TTT TTA GGG AAG ATC
- E
T HXB2436E+437T
- G--
- C-
- T
Pathway 1
- C-
- R
E T Pathway 2
- A-- G-- -C--
- E
T Pathway 3
- G-- -C-
438
W TGG
- R
A--
SLIDE 10
Effect of NC/p1 changes on viral replicative capacity
100 1000 10000 100000 1000000 10000000 1 2 3 4 5 6 7 8 9 11 12 13 Days pg p24/ml HXB2 436E+437T
- 436E
+435R +438R
SLIDE 11
Effect of evolution on Gag cleavage analyzed by quantitative immunoblotting
MATRIX
10 20 30 40 50 60 50 nM 100 nM Concentration RO033-4649 Ratio p17/sum of p17reactive products HXB2 436E + 437T
- 436E
+ 438R + 435R
CAPSID
10 20 30 40 50 60 70 80 90 50 nM 100 nM Concentration RO033-4649 Ratio p24/sum of p24 reactive products HXB2 436E + 437T
- 436E
+ 438R + 435R
SLIDE 12
Effect of observed evolution on PI susceptibility
SLIDE 13
Modulation of Gag cleavage in relation to PI resistance
Viral optimum Gag cleavage efficiency Replicative Capacity Resistant Hyper Susceptible?
SLIDE 14