Genetic Variations of CD55 and Pathogenesis of

Pandemic A(H1N1)2009 Influenza

ZHOU JIE, Jane

August 19, 2014

Pandemic A(H1N1)2009 influenza

First report on spring 2009 by US CDC. WHO signaled the 1st influence pandemic in this centaury.

A(H1N1)pdm09 virus derived from a reassortment of avian H1N1, classical swine H1N1 and human

seasonal H3N2 viruses.

people under 65 years of age infected preferentially.

high rate of severe infection in younger patients. As of Oct 2010, at least 299 severe infection and 83

death in HK.

1/3 of the severe cases don’t have predisposing comorbidities, including chronic heart or pulmonary

diseases and metabolic disorders.

WHO identified the studies of role of genetic factors on susceptibility to severe influenza as a priority.

Aim: Host genetic variation may affect the disease severity of A(H1N1)pdm09 infection.

Introduction

Genome-wide association study (GWAS)in a pilot cohort

SNP

　

allele

　 allelic distribution 　

p valuemild cases (%)

severe cases (%)

rs6691942 C 0.4808 0.84 1.333E-04

rs4844592 T 0.4231 0.76 5.476E-04

rs2564978 T 0.4231 0.76 5.476E-04

rs1507758 G 0.4231 0.76 5.476E-04

rs10864231 T 0.4231 0.76 5.476E-04

rs6700168 C 0.5769 0.24 5.476E-04

Selected genetic association result for CD55 SNPs in GWAS.

CD55, a complement regulatory protein.

CD55

rs2

56

49

78

rs4

84

45

92

rs6

69

19

42

rs6

70

01

68

rs1

08

64

23

1

Rs1

50

77

58

Exon 1 2 3 4 5 6 78 9 10 11 12 13 14

Linkage disequilibrium (LD) pattern of CD55 variants

Genotypic distribution and logistic regression analysis of rs2564978 in study participants.

　 Severe patients Mild controls

　 (n = 177) (n = 248)

Genotypic distribution, n (%)

TT 94 (53.1) 94 (37.9)

CT 60 (33.9) 109 (44.0)

CC 23 (13.0) 45 (18.1)

Univariate regression analysis

OR (95% CI) 1.85 (1.15-2.78)

P value 0.0019

Multivariate regression analysis

OR (95% CI) 1.75 (1.13-2.70)

P value 0.0110

Allele-specific effect of rs2564978 on CD55 expression in peripheral blood monocytes

0

0.1

0.2

0.3

0.4

T/T C/T C/C Genotype

Re

lati

ve

CD

55

mR

NA

le

ve

ls

p=0.003

p=0.038

P=0.0003

CC CT TT Genotype

L

og

10

(ME

FL

)

5

4

3

expression Quantitative Trait Loci (eQTL)

• eQTL, expression-related variations, mapped by paralleled genome-wide analysis of gene

expression and genetic variations in LCLs and various human tissues, populations and in

response to different stimuli.

• Interpret association signal, prioritize causal gene(s), provide immediate insight about disease

pathogenesis…

http://eqtl.uchicago.edu/Home.html

Luciferase assay of CD55 promoter variants

p=0.0006

Luc

Relative Luc Activity

CI -C---Ins---

CD -C---Del---

TI -T---Ins---

TD -T---Del---

0 10 20 30 40

p=0.0002

rs25

6497

8 C

>T

rs38

4137

6 in

del

Complement dependent cytolysis (CDC) assays in

respiratory epithelial cell lines

0

20

40

60

80

1 2 3

A549

α-CD55iso-ctrl PBSTreatment

Cel

l lys

is (

%)

p<0.00001

p=0.0008

0

10

20

30

40

1 2 3C

ell l

ysis

(%

)

p=0.0001

p=0.0004

α-CD55iso-ctrl PBSTreatment

BEAS-2B

Influenza infection enhances CD55 expression

0.00

0.01

0.02

0.03

0.04

0.05

0.06

No

rma

lize

d C

D5

5 m

RN

A l

ev

els

p=0.0193

NS

7hpi 24hpi

mockH1N1pdm

A B

0

10

20

30

40

50

12hpi 24hpi 32hpi

mockH1N1pdm

CD

55

le

ve

ls (

pg

/ml)

Summary

• Genetic association study: rs2564978 T/T genotype associated with H1N1pdm severe

infection.

• CD55 expression assay: rs2564978 T/T genotype carriers showing the lower

expression in human peripheral blood monocytes.

• Luciferase assay: T/T genotype and rs3841376 del displaying lower transcriptional

activity. The indel dictating CD55 transcriptional regulation.

• CD55 protecting A549 and BEAS-2B cells from complement attack.

• Upon flu infection, CD55 (membrane and soluble form) was up-regulated.

Journal of infectious Diseases. ZHOU. J 2012

On-going Study

To define the role of CD55 in influenza virus-infected CD55-KO mice.

0

20

40

60

80

100

120

0 6 7 8 9 10 11 12 1314 15 16 17

CD55KO

Balb/c

Sur

viva

l Rat

e (%

)

Day(s) post inoculation

Acknowledgement

• Professor Kwok-Yung Yuen 袁国勇教授

• My team:

CHU Hin 朱轩

CHENG Zhongshan (Sam) 程中山

LI Cun 李存

WONG Ho Yin (Bosco)

• Health and Medical Research Fund (HMRF), HKSAR &

Providence Foundation Limited in memory of the late Dr Lui Hac

Minh

jiezhou@hku.hk