what is sars-cov-2 serological testing and why do we need it? · what is sars-cov-2 serological...
TRANSCRIPT
What is SARS-CoV-2 serological testing and why do we need it?
Florian KrammerMount Sinai Professor in Vaccinology
Icahn School of Medicine at Mount Sinai
ICAP ‘SARS-CoV-2 serological testing: What is it and what does it mean?’
WebinarMay 13th, 2020
What is serology?• When we get infected with viruses or other pathogens, our B-cells make
antibodies to the invading microbe to ‘neutralize it’• There antibodies can be found in the blood serum, hence the name
PCR Testing Serology Testing
Why is serology useful?• Finding donors for convalescent plasma therapy
• Sero-surveys to determine true infection rates
• Tool to understand dynamics of antibody responses to SARS-CoV-2
• Establish correlates of protection• Is somebody protected by the antibody response?• Does the antibody response need to reach a certain level to be protective?
The spike protein is the main target of neutralizing antibodies for many coronaviruses
PBD # 6VXX
The spike protein is the main target of neutralizing antibodies for many coronaviruses
How does this work? – Negative serum:
How does this work? – Positive serum:
Types of tests
Sensitivity and specificity• Sensitivity: How many real positives are detected
• For serology that is often influenced by when sample is taken
• Specificity: How many false positives are detected
• Both should be in the high 90% range• Only use tests with known performances and at least an FDA EUA• Different tests are useful for different things
Human serum reactivity in RBD and spike ELISA
1 0 0 1 0 0 0 1 0 0 0 0
0 . 0
0 . 5
1 . 0
1 . 5
2 . 0
2 . 5
m R B D
R e c i p r o c a l d i l u t i o n
OD
(4
90
nm
)
1 0 0 1 0 0 0 1 0 0 0 0
0
1
2
3
4
m S p i k e
R e c i p r o c a l d i l u t i o n
OD
(4
90
nm
)
S A R S - C o V - 2 s a m p l e s
o t h e r n e g a t i v e c o n t r o l s a m p l e s
p o s t N L 6 3
Co
nt r o
l s
am
pl e
s
SA
RS
- Co
V- 2
se
r oc
on
ve
r t er s
0 . 1
1
1 0
1 0 0
1 0 0 0
1 0 0 0 0
m R B D
Ar
ea
un
de
r c
ur
ve
(A
UC
)
Co
nt r o
l s
am
pl e
s
SA
RS
- Co
V- 2
se
r oc
on
ve
r t er s
0 . 1
1
1 0
1 0 0
1 0 0 0
1 0 0 0 0
m S p i k e
Ar
ea
un
de
r c
ur
ve
(A
UC
)
Amanat et al., Nat. Med., in press
Spike ELISA endpoint titers correlate well with virus neutralization
1 0 1 0 0 1 0 0 0 1 0 0 0 0 1 0 0 0 0 0
0 . 1
1
1 0
1 0 0
1 0 0 0
1 0 0 0 0
C o r r e l a t i o n
m S p i k e E L I S A a n d m i c r o n e u t r a l i z a t i o n a s s a y
s p i k e E L I S A e n d p o i n t t i t e r
mic
ro
ne
utr
ali
za
tio
n I
C5
0
n=3, overlapping
Spearman r=0.9279P<0.0001
Amanat et al., Nat. Med., in press
Mount Sinai Plasma Donors• >22,000 donors screened by ELISA
• Mostly mild cases• PCR confirmed donors• Donors with suspected COVID19 (but without PCR confirmation)
• >250 patients treated with convalescent plasma
• ELISA and PCR results from the ~1350 donors can be found at: https://www.medrxiv.org/content/10.1101/2020.04.30.20085613v1
C O V I D 1 9 - s u s p e c t e d d o n o r s
A n t i b o d y p o s i t i v e ( n = 2 6 9 , 3 8 . 2 % )
A n t i b o d y n e g a t i v e ( n = 4 3 6 , 6 1 . 8 % )
P C R - c o n f i r m e d d o n o r s
A n t i b o d y p o s i t i v e ( n = 5 6 8 , 9 9 . 5 % )
A n t i b o d y n e g a t i v e ( n = 3 , 0 . 5 % )
Proportion of antibody positive donors
Wajnberg et al., under review
Proportion of antibody positive donors
ne
ga
t i ve
80
16
03
20
96
0
28
80
0
2
4
6
8
1 0
1 2
1 4
1 6
1 8
2 0
2 2
2 4
2 6
2 8
3 0
3 2
3 4
3 6
3 8
4 0
4 2
4 4
4 6
4 8
5 0
E L I S A t i t e r p o s t s y m p t o m o n s e t
u p o n i n i t i a l d o n o r s c r e e n
r e c i p r o c a l t i t e r
da
ys
po
st
sy
mp
tom
on
se
t
1 0 2 0 3 0 4 0
I n c r e a s e i n t i t e r s o f P C R c o n f i r m e d / A b l o w i n d i v i d u a l s
b e t w e e n 1s t
a n d 2n d
s c e e n
d a y s s i n c e s y m p t o m o n s e t
re
cip
ro
ca
l ti
ter
4 0
8 0
1 6 0
3 2 0
9 6 0
2 8 8 0
A B
Wajnberg et al., under review
What does this all mean?• Usually, antibodies are a good thing• Antibodies protect from (re)infection for most viruses• Neutralizing antibodies are usually associated with protection
from viruses• We know that antibodies protect from human CoV infections
• We need to now proof that antibodies against SARS-CoV-2 protect from infection
• What titer is protective?• Important for vaccine development
Acknowledgements
Adolfo Garcia-SastreLisa Miorin
Teresa Aydillo
Tom Moran
Viviana SimonMaria Bermudez-Gonzalez
Denise Jurczyszak
Katherine Kedzierska (U Melbourne)Jussi Hepojoki (U Helsinki)Olli Vapalahti (U Helsinki)
Department of Microbiology/ Icahn School of Medicine at Mount Sinai
Florian Krammer, [email protected]://labs.icahn.mssm.edu/krammerlab/Twitter: @florian_krammer
Ania Wajnberg(Mount Sinai Hospital)
