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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.
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