antigenic mimicry of the hiv envelope by aids-associated pathogens

Antigenic mimicry of the HIV

envelope by AIDS-associated pathogens.

Wednesday 15th October, 2008

Cameron Dunlop Oxford University

• 2G12, a broadly neutralising antibody, recognises an oligomannose cluster on gp120

Project Background - 2G12

Calarese et al., 2003, Science



α1-2

β1-4

β1-4

α1-3

α1-2 α1-2α1-2

α1-6

α1-6

α1-3

Self (HIV) oligomannose




Manα1-2Man


α1-2

β1-4

β1-4

α1-3

α1-2 α1-2α1-2

α1-6

α1-6

α1-3




• High avidity antibodies to oligomannose are not found in human sera



• How did 2G12 arise?


• Guillain-Barre syndrome.

From Scanlan et al Nature 2007

Antigenic mimicry

Core Lipid ACore Lipid A CeramideCeramide

Campylobacter jejuni Self GM1

N-Acetylglucosamine Galactose Sialic acidGlucose

β1-3 β1-4

α2-3

β1-3 β1-4

α2-3

β1-4

• Guillain-Barre syndrome.• Antibodies against Campylobacter jejuni

oligosaccharides cross-react with self-sugars on gangliosides leading to autoimmune disease.

From Scanlan et al Nature 2007

Core Lipid ACore Lipid A CeramideCeramide

Campylobacter jejuni Self GM1

N-Acetylglucosamine Galactose Sialic acidGlucose

β1-3 β1-4

α2-3

β1-3 β1-4

α2-3

β1-4

Antigenic mimicry


α1-2

β1-4

β1-4

α1-3

α1-2 α1-2α1-2

α1-6

α1-6

α1-3

Candida albicans mannan

N-Acetylglucosamine Mannose

α1-2 α1-2 α1-2

α1-2 α1-2 α1-2 α1-2

α1-2

α1-6 α1-6 α1-6 α1-6

α1-3

α1-3 linkage present in S.cerevisiae

α1-2

Could 2G12 be a response to something other than HIV-1?

Scanlan et al., Nature, 2007

2G12 can bind to WT Candida albicans, but not WT Saccharomyces cerevisiae

2G12 can also bind to Candida tropicalis, but Candida glabrata

0

250

500

750

1000

1250

0.1 1 10 100 10002G12 [nM]

Med

ian

Fluo

resc

ence

Affinity of 2G12 for the C.albicanssurface

Apparent affinity of ~11nM, comparable with the binding of 2G12 to gp120

Carbohydrate recognition can explain antigenic mimicry between C. albicans

and HIV-1 gp120.ce

ll cou

nt

100 101 102 103 104

0

19

38

56

75

cell c

ount

100 101 102 103 104

0

19

38

56

75

b12 binding (FITC) 2G12 binding (FITC)

No monosaccharide 2M fructose 2M glucose


and HIV-1 gp120.

0

200

400

600

800

01101001000

monosaccharide [mM]

med

ian

fluor

esce

nce

Monosaccharide [mM]

Med

ian

fluor

esce

nce

fructose

glucose

• Candida albicans is a common opportunistic infectious agent in HIV +ve people.


and HIV-1 gp120.


• Could maturation of B cells expressing anti-Candida antibodies in the presence of HIV lead to cross-reactive antibodies?


and HIV-1 gp120.


• Could maturation of B cells expressing anti-Candida antibodies in the presence of HIV lead to cross-reactive antibodies?

• Immunisation trials in rabbits using various yeast species along with modified gp120 are underway.


and HIV-1 gp120.

Breaking tolerance

• Cross-reactivity as a method of overcoming self-tolerance is not a new concept – In 1965 Weigle et al were able to induce an immune response to a self protein by immunising with a chemically modified version.

Chemical modifications to oligomannose in situ

Oligomannose: not immunogenic

OH O

H O

O H

OH

O-Man8GlcNAc2

gp120


OH O

H O

O H

OH

O-Man8GlcNAc2

gp120

Conversion of terminal hydroxyls (C6 only) to

aldehyde groups by

H2



Oligomannose with aldehyde groups: structurally similar yet

immunogenic?

OH O

H O

O H

OH

O-Man8GlcNAc2

gp120

OH O

H O

O H

O

O-Man8GlcNAc2

gp120H2


Conversion of terminal hydroxyls (C6 only) to

aldehyde groups by


OH O

H O

O H

OH

O-Man8GlcNAc2

gp120endoglycosidase

MS of gp120 control

kifgp120kif + DMP

Spot number: 27Laser power: 100Laser rate: 5

27-JUN-2007, 11:21:55Collision energy: 0

TofSpec-E, GAA069BK (07/166)

1200 1250 1300 1350 1400 1450 1500 1550 1600 1650 1700 1750 1800 1850 1900 1950 2000 2050 2100 2150m/z0

100

%

070306 1 (0.050) M2 [Ev-20631,It59] (0.750,1192:2166); Sb (99,50.00 ); Cm (1:26) TOF LD+ 1.28e41905.8

1257.3

1241.3

1743.7

1581.51258.3

1419.41259.31403.4

1260.51420.4

1582.5

1583.6

1742.3

1744.6

1745.7

1903.71746.8

1906.7

1907.8

1908.9

1910.0

1921.72041.7

Man9GlcNAc2

(oligomannose)

DMP Old (08/97)

m/z1890 1892 1894 1896 1898 1900 1902 1904 1906 1908 1910 1912 1914 1916 1918 1920 1922 1924

%

0

100

%

0

100

C080010 4 (0.131) M2 [Ev-22872,It52] (0.750,1692:2084); Sb (99,10.00 ); Sm (SG, 2x2.00); Cm (1:19) TOF LD+ 9071905.6

1903.6

1902.51901.51897.61890.7 1892.4

1896.11899.5

1904.4

1907.6

1909.6

1921.5

1912.51910.51916.4

1913.5

1917.7 1919.51922.7

1923.5 1924.6

C080006 206 (5.011) M2 [Ev-27900,It48] (0.750,1693:2084); Sb (99,10.00 ); Sm (SG, 2x2.00); Cm (1:217) TOF LD+ 1.30e31905.6

1897.01892.8

1890.8 1895.71894.8 1903.81898.9 1901.8

1899.6 1902.8

1907.7

1922.9

1921.7

1915.8

1909.61914.61913.0

1911.2

1917.9

1916.91919.8

1920.7

1923.91924.8

kif

control

gp120kif + DMP

gp120 control

MS of gp120 control (focus on Man9GlcNAc2 peak)

DMP Old (08/97)

m/z1890 1892 1894 1896 1898 1900 1902 1904 1906 1908 1910 1912 1914 1916 1918 1920 1922 1924

%

0

100

%

0

100

C080010 4 (0.131) M2 [Ev-22872,It52] (0.750,1692:2084); Sb (99,10.00 ); Sm (SG, 2x2.00); Cm (1:19) TOF LD+ 9071905.6

1903.6

1902.51901.51897.61890.7 1892.4

1896.11899.5

1904.4

1907.6

1909.6

1921.5

1912.51910.51916.4

1913.5

1917.7 1919.51922.7

1923.5 1924.6

C080006 206 (5.011) M2 [Ev-27900,It48] (0.750,1693:2084); Sb (99,10.00 ); Sm (SG, 2x2.00); Cm (1:217) TOF LD+ 1.30e31905.6

1897.01892.8

1890.8 1895.71894.8 1903.81898.9 1901.8

1899.6 1902.8

1907.7

1922.9

1921.7

1915.8

1909.61914.61913.0

1911.2

1917.9

1916.91919.8

1920.7

1923.91924.8

control

gp120 + DMP

gp120 control

DMP-modified kifunensine treated gp120 and control (focus on Man9GlcNAc2 peak)

Selective oxidation as a scaffold for immunogen diversification

O

H O

H O

O H

O - M a n 8 G l c N A c 2

O

Selective oxidation as a scaffold for immunogen diversification

O

H O

H O

O H


O

O

H O

H O

O H

O -M a n 8 G l c N A c 2

O

O H

O

H O

H O

O H


N

N H

O 2N

N O 2

O

H O

H O

O H


N

N H

OR

O

H O

H O

O H


S

H N

R

O

H O

H O

O H


N

O R

Ongoing work• Increase the efficiency of the aldehyde

formation reaction on gp120’s glycans.• Immunise directly with this, to investigate

methods of overcoming tolerance… in addition to using the aldehyde groups as attachment points for other immunogenic chemical groups.

Acknowledgements

Chris Scanlan Nicole ZitzmannRaymond Dwek

John OfferFatma MansabDave Harvey

Mark Wormald…and everyone in

the Zitzmann lab

Dennis BurtonIan Wilson

Dan CalareseOla Blixt

Rena Astronomo

antigenic mimicry of the hiv envelope by aids-associated pathogens

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