What is SARS-CoV-2 serological testing and why do we need it? · What is SARS-CoV-2 serological testing and why do we need it? Florian Krammer Mount Sinai Professor in Vaccinology.

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

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m R B D

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(A

UC

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m S p i k e

Ar

ea

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r c

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(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

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tom

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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

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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)