HLAB27Associated Escape Mutations Dramatically Reduce Viral Fitness of HIV1

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HLA-B27-Associated Escape Mutations Dramatically
Reduce Viral Fitness of HIV-1

• Arne Schneidewind
• Partners AIDS Research Center
• Massachusetts General Hospital
• Boston

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Background
HLA-B27 is a protective MHC class I allele in
HIV infection - Genetic effect observed late in
disease (Gao et al, Nat Med., 2005) -
immunodominant CD8 response targets KK10 in p24
capsid - CTL escape mutations in KK10 occur very
late in disease Studies have illustrated that
drug resistance mutations and CD8 escape
mutations can impact viral replication Hypothesis
The effect of CD8 escape mutations on viral
fitness may contribute to immune control
associated with HLA-B27
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Goals
Examine the impact of CD8 escape mutations in
B27- KK10 (KRWIILGLNK) on HIV-1 replicative
fitness Assess the ability of compensatory
mutations to rescue the fitness defects of a CD8
escape mutation Explore mechanisms for the
late escape from this immunodominant CD8 T cell
response
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Viral Escape in B27-KK10
Various CD8 escape and compensatory mutations
in KK10 have been previously described Goulder
et al Nature Med 1997 Kelleher et al JEM 2001
Goulder et al Nature 2001 Feeney et al JVI
2004 Ammaranond et al AIDS Res Hum Retroviruses
2005
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Viral Escape in B27-KK10
Various CD8 escape and compensatory mutations
in KK10 have been previously described Goulder
et al Nature Med 1997 Kelleher et al JEM 2001
Goulder et al Nature 2001 Feeney et al JVI
2004 Ammaranond et al AIDS Res Hum Retroviruses
2005
L268M occurs early after infection and is a
weak CD8 escape mutation
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Viral Escape in B27-KK10
Various CD8 escape and compensatory mutations
in KK10 have been previously described Goulder
et al Nature Med 1997 Kelleher et al JEM 2001
Goulder et al Nature 2001 Feeney et al JVI
2004 Ammaranond et al AIDS Res Hum Retroviruses
2005
Mutation R264K at the anchor position P2
diminishes binding to HLA-B27 and represents the
predominant CD8 escape mutation in KK10
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Viral Escape in B27-KK10
Various CD8 escape and compensatory mutations
in KK10 have been previously described Goulder
et al Nature Med 1997 Kelleher et al JEM 2001
Goulder et al Nature 2001 Feeney et al JVI
2004 Ammaranond et al AIDS Res Hum Retroviruses
2005
An upstream compensatory mutation (S173A) has
been proposed - Kelleher / Brander (manuscript
in preparation)
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Compensatory Mutation lies in Proximity to
Escape Mutations
N-term p24 capsid
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Compensatory Mutation lies in Proximity to
Escape Mutations
N-term p24 capsid
R264K
L268M
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Compensatory Mutation lies in Proximity to
Escape Mutations
N-term p24 capsid
S173A
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Escape Mutation R264K Reduces Infectivity
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Escape Mutation R264K Reduces Replicative
Capacity
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Escape Mutation R264K Reduces Replicative
Capacity
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Escape Mutation R264K Reduces Replicative
Capacity
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Escape Mutation R264K Reduces Replicative
Capacity
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Escape Mutation R264K Reduces p24 Production on
PBMCs
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Escape Mutation R264K doesnt alter Release of
p24
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Escape Mutation R264K doesnt alter Cleavage of
Gag
p24 ?
p55 ?
p24 ?
supernatant
intracellular
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Conclusions

• CD8 escape mutation R264K exhibits a dramatic
  defect in infectivity and replicative capacity
• Upstream mutation S173A in helix 2 effectively
  compensates for the fitness defect of R264K
• The dramatic fitness cost of R264K, and the
  requirement for a simultaneous compensatory
  mutation, may explain the late escape from this
  CD8 response
• R264K variant seems to be blocked at an early
  step of the replicative cycle

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Acknowledgment
Mark A. Brockman Sylvie Le Gall Rahma I.
Adam Matthew P. Lahaie Christian Brander Tony
Kelleher Bruce D. Walker Todd M. Allen This
project was supported by NIH Grant R21 AI067078