The document discusses the necessity of a robust serological test to detect neutralizing antibodies (NAbs) against SARS-CoV-2 to evaluate infection rates, herd immunity, and vaccine efficacy. It explains various testing methods including molecular and serological tests, highlighting the advantages of the c-pass surrogate virus neutralization test (SVNT) which is easy, safe, and rapid. The SVNT demonstrates strong specificity and sensitivity for detecting NAbs, making it useful for a wide range of COVID-19 investigations.

1. Detecting Neutralization
Antibodies to COVID-19
Group 2

2. Agenda
• Virus Structure
• Mechanism of infection
• Tests and timing
• Neutralization antibodies and associated tests
• C-Pass SARS Cov-2 Neutralization antibody
kit (sVNT)
• Pros and Comparison

3. Introduction
A robust serological test to detect neutralizing
antibodies to SARS Cov-2 is needed to
determine not only the infection rate, herd
immunity and predicted humoral protection, but
also vaccine efficacy during clinical trials after
large scale vaccination.

4. Transmission
mechanism of
Covid-19
Binding of coronavirus spike protein
(red) to an ACE2 receptor (blue) on
a human cell leads to the
penetration of the virus in the cell.
Spike protein (red) contains 2
subunits: S1 (yellow) and S2. S1
yellow contains receptor binding
domain.

5. Timing for Molecular Tests Post
Infection
Viral RNA/
Antigen/
Antibody levels
in blood
To Time

6. Nucleic acid and Antibody- Based Tests
to Reduce Disease Period
Nucleic Acid Test
• Highly sensitive test to detect the
presence of the virus itself very early
after infection.
• Dependent on sampling the
appropriate tissue or fluids to avoid
false negatives.
• Reduced disease period by revealing
very early infected who can
immediately self-quarantine.
Serological Test (Antibody-Based)
• Detects antibodies generated by
infected people during their natural
immune response.
• Antibody test result could be positive
when the nucleic acid result is
negative.
• Permits asymptomatic individuals to
confirm past infection from which they
recovered.
Complementary tests to confirm Infection

7. Protein Based capture tests for IgG and IgM
Receptor Binding Domain
(RBD) of SARS-Cov-2
Nucleocapsid Protein
(NP) of SARS-Cov-2
Immune response
antibodies (IgM & IgG) to
NP from patient sample
Immune response
antibodies (IgM & IgG) to
RBD from patient sample
RBD of the spike
protein binds to
ACE2 receptor

8. Protein Based capture tests for IgG and IgM

9. Protein Based capture tests for IgG and IgM

10. Protein Based capture tests for IgG and IgM
Mouse anti-human IgG or IgM
detection antibodies

11. Protein Based capture tests for IgG and IgM
Detects only anti-
Spike S1- RBD
protein antibodies.
IgG and IgM can be
detected together or
in separate wells.
Quantitative assay.
Useful for diagnostic,
vaccine and drug
development.
Detects only anti-
Spike S1- RBD and
anti nucleocapsid
protein antibodies.
IgG and IgM can be
detected together in
each wells.
Qualitative assay.
Useful for diagnostic,
vaccine and drug
development.

12. Neutralization Antibodies (NABs)
• Block the virus from entering the
cells.
• Typically generated about 5 to 10
days post infection and peak about
20 to 30 days.
• Can provide sustained immunity from
four to six months.
• Typically produced from infection
(natural immunity) or vaccination.

13. Pre-Existing Neutralization Ab Tests
Virus Neutralization Test
• Live cells and live SARS
Cov-2 virus
(DANGEROUS) required.
• Specialized biosafety level
3 (BSLV3) containment
facility.
• Requires 2-4 days with
complex equipment and
reagents.
Pseudo virus based VNT
• Live cells and live pseudo-
virus (SAFER) required.
• (BSL2) Lab.
• Requires 2-4 days with
complex equipment and
reagents.
SARS Cov-2 surrogate VNT
(CPASS Genscript)
• No cells or live virus
required (Basic ELISA Kit).
• BSL2 Lab.
• Requires 1 to 2 hours with
basic equipment and
reagents.
• Species independent (can
be used with any organism
infected and recovered
from SARS Cov-2 virus.

14. SARS-Cov-2 Surrogate Virus Neutralization
c-Pass Test
Species Independent

15. How does Surrogate Virus Neutralization
Assay works (s-VNT)?

16. Advantages of cPass s-VNT assay for
detecting immunoglobins
Immunoglobin Agnostic
• Permits the detection of
any immune response
antibody that binds to RBD
and blocks its interaction
with ACE2.
• Not limited to IgG and IgM
(higher sensitivity).
• Species independent.
RBD is in solution
• RBD is not coated on plate.
• Much lower probability of
confirmational differences
for RBD in the solution vs
coated to a plate surface.
• Immunoglobins react with a
more native conformation
of RBD and its associated
antigenic sites (higher
specificity).
Dual Detection and functional
assay
• RBD must bind to ACE2
coated plate (neutralizing
antibody dependent).
• Detects the presence of
neutralizing antibodies with
sensitivity and specificity
that rivals traditional IgG
and IgM ELISA tests.
• Requires 1 hour with basic
equipment and reagents.

17. Comparison of SVNT with RBD coated
ELISA (IgG & IgM)

18. Grouped Clinical Data (GenScript SVNT Results)

19. Performance cross species c-pass SVNT
• Tested Rabbit and Ferret.
• In principle as the blocking is on the
virus protein, this methodology should
work for all species.

20. Summary
In summary, we have addressed the challenge
of COVID-19 serology with an approach that
enables the detection of NAbs in an easy, safe
and rapid manner with enhanced specificity and
sensitivity. Although the sVNT assay may never
be able to completely replace cVNT, data
indicate that the performance of sVNT is well
correlated with that of both cVNT and pVNT. Its
application can cover many aspects of COVID-
19 investigation from contact tracing,
seroprevalence surveying and
reservoir/intermediate animal tracking to the
assessment of herd immunity and longevity of
protective immunity. It can also be used to
assess vaccine efficacy during preclinical and
clinical trials of different vaccine candidates and
to monitor neutralizing titers in vaccinees after
mass vaccination in human populations.

21. REFERENCES
• A SARS-CoV-2 surrogate virus neutralization test based on antibody-mediated blockage of
ACE2–spike protein–protein interaction (nature article).
• https://doi.org/10.1038/s41587-020-0631-z
• COVID-19 Detection | cPass™ Kit Technology (genscript.com)

22. Thank you
Group 2