Natural control of HIV infection is associated with an isotype switched IgG antibody response to HIV Gag

antigens in patients with 'non-protective' HLA-B alleles Martyn A French1, Rob J Center2, Kim M Wilson3, Ibrahim Fleyfel1, Sonia Fernandez1, Anna Schorcht2, Ivan Stratov2, Marit Kramski2,

Stephen J Kent2, Anthony D Kelleher4

1. University of Western Australia, Perth, Australia2. University of Melbourne, Melbourne, Australia3. NRL, Melbourne, Australia4. University of New South Wales, Sydney, Australia

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• CD8+ T cells and ‘protective’ HLA-B molecules (HLA-B*5701, -B2705, -B*14+Cw0802, -B*52)

• NK cells (KIR and HLA-Bw4 or HLA-C)• Plasmacytoid dendritic cells• Antibodies

- Antibody-dependant cell-mediated cytotoxicity?- Antibodies to Gag proteins?- IgG2 antibodies?

Immune control of HIV infection

Diversification of antibody responses through immunoglobulin isotype switching

Abbas et al. 2007

IgM IgG Subclass

es

IgE IgA

IFN-g IL-4APRIL, BAFF, TGF-β, IL-10 IL-21

TFH

IgG3 IgG1 IgG2 IgG4

• Polysaccharide antigens induce a predominantly IgG2 antibody response

• Preferential binding to FcgRIIa• Deglycosylation of Fc region does not decrease

binding to FcgRIIa

• Covalent dimerisation• Dominant IgG subclass in plasma immune

complexes

Functional characteristics of IgG2 antibodies

HIV Patients• 32 HIV controllers, including 14 elite controllers• 21 non-controllers with RNA >10,000 cps/mL and CD4+ T cell count <100/mL

Methods• IgG1 and IgG2 Abs to HIV proteins by WB assay• IgG1 and IgG2 Abs to gp140 Env protein and rp55 by ELISA• NK cell-mediated ADCC activity to gp140 Env protein and Env and Gag peptides• Sequenced-based HLA typing on genomic DNA

Patients and Methods

IgG1 antibodies to all HIV proteins, except gp41, are higher in HIV controllers

IgG1 Response

Ban

d In

tens

ity

0

1

2

3

4

5

P = 0.002 P < 0.001 P = 0.006P < 0.001 P = 0.440P < 0.001 P = 0.001

Gag antigens dominate in the IgG2 antibody response against HIV

IgG2 Response

Ban

d In

tens

ity

0

1

2

3

4

5

P = 0.014 P = 0.034 P = 0.045

IgG2 antibodies to rp55 were only detected in HIV controllers

0tan28a566028

0tan28a566028

0tan29a566029

controllers noncontrollers

neg

0.1

0.2

0.3

0.4

0.5

0

0.6

OD

450

IgG1

0.2

0.4

0.6

0.8

1.0

1.2

controllers noncontrollers

OD

450

neg

IgG2P=0.09 P=0.14

IgG1 anti-rp55 IgG2 anti-rp55

IgG1 and IgG2 antibodies to gp140 Env protein did not differentiate controllers and non-controllers

controllers

non-controllers

P = 0.12

End

poin

t tite

r (lo

g10)

controllers non-controllers

P = 0.34

End

poin

t tite

r (lo

g10)

non-controllers

IgG2 anti-gp140 Env proteinIgG1 anti-gp140 Env protein

HIV controllers exhibit higher ADCC activity to gp140 Env protein

ADCC activity against gp140 Env protein was significantly higher in elite controllers than non-controllers (p=0.03)

Antibody responses to HIV proteins in controllers without or with ‘protective’ HLA-B alleles

Antibody response HIV Controllers without protective HLA-B alleles#

(median, IQR)

HIV Controllers with protective HLA-B#

alleles (median, IQR)

P value

IgG1 anti-p18 4 (3-4) 3 (2-4) 0.11IgG1 anti-p24 4(3-4) 4 (2-4) 0.65IgG1 anti-p32 3.5 (2.25-4) 2 (2-3) 0.04IgG1 anti-p51 4 (2.25-4) 4 (2.25-4) 0.65IgG1 anti-p66 4 (4-4) 4 (3.25-4) 0.42IgG1 anti-gp41 4 (4-4) 4 (4-4) 1.0IgG1 anti-gp120 3.5 (2-4) 3 (2.25-4) 0.95IgG2 anti-p18 1.5 (1-3) 1 (1-2) 0.10IgG2 anti-p24 1.5 (0-3.75) 0 (0-2) 0.16IgG2 anti-gp41 1 (1-2) 1 (1-2) 0.91ADCC antibodies to gp140 Env protein

0.218 (0.024 - 0.412) 0.183 (0.048 - 0.634) 0.51

# = HLA-B*57, -B*27, -B*52, B*14+Cw0802

IgG2 antibodies to p24 are higher in HIV controllers who do not carry HLA-B*57

IgG2 anti-p24

IgG1 anti-p18 IgG1 anti-p32

IgG2 anti-p18

High-level IgG2 antibodies to one or more Gag protein (p18, p24, rp55) are most common in HIV controllers

not carrying ‘protective’ HLA-B alleles

IgG2 anti-Gag HLA-B*57 or B*52 HLA-B*27 or B*14No ‘protective’

HLA-B allele

Yes 2 4 9

No 10 4 3

p=0.016 and 0.004 for trend

• IgG2 antibodies to HIV Gag proteins may contribute to control of HIV infection• Preferential binding to FcgRIIa (major FcgR on pDCs)• Deglycosylation of Fc does not decrease binding to FcgRIIa• Phagocytosis-enhancing antibodies (bacteria, ?viruses)

• Such antibodies might enhance innate responses to HIV and/or adaptive immune responses to Gag

• Strategies for vaccination with HIV Gag proteins might include enhancement of IgG isotype switching

Summary and Conclusions

TLR7

Gag+

RNA IgG1

FcgRIIa

IFN-a and IFN-l

Interferon-stimulated genespDC-dependant NK cell activationIRF-7

CD8+

T cell

CD4+

T cell

Pro-inflammatory cytokines

IgG2

IgG3MHC I

MHC II

= Endosomes

B cell

CD70

X

NFkB

Induction of innate responses to HIV and/or adaptive responses to Gag by pDC and isotype-

switched IgG antibodies: a hypothesis

French MA, 2012 (unpublished)

Control of HIV replication was better in patients possessing ‘high affinity’ FcgRIIa genotypes who produced IgG2 anti-p24

after vaccination with FPV/Gag-Pol/IFN-g DNA

P=0.002 for FC recipients (o)P=0.0001 for all patients

French MA et al. AIDS 2010;24:1983-90