dynamicof neutralizing antibody productions correlates with survival from covid 19 infection

1. Role of Neutralizing antibodies in
Covid 19
Prof. Ashok Rattan,
MD, MAMS,
Common Wealth Fellow, INSA DFG Fellow, SEARO Temporary Advisor,
WHO Lab Director (CAREC/PAHO)
Advisor: Pathkind Labs Knowledge Forum, R & D and Quality

2. SARS CoV 2

4. Zhao J et al: Antibody responses to SARS-CoV-2 in patients of
novel coronavirus disease 2019

5. • The longitudinal tracking of re-exposure after the disappeared symptoms of the
SARS-CoV-2-infected monkeys :
• weight loss in some monkeys, viral replication mainly in nose, pharynx, lung and
gut, as well as moderate interstitial pneumonia at 7 days post-infection (dpi) were
clearly observed in rhesus monkeys after the primary infection.
• After the symptoms were alleviated and the specific antibody tested positively,
• half of infected monkeys were re-challenged with the same strain
• Neither viral loads in nasopharyngeal and anal swabs along timeline nor viral
replication in all primary tissue compartments at 5 days post-reinfection (dpr) was
found in re-exposed monkeys.
• Monkeys with re-exposure showed no recurrence of COVID-19, similarly to the
infected monkey without re-challenge.
Bao et al: Beijing Key Laboratory for Animal Models of Emerging and Remerging Infectious Diseases

7. Immunological surrogate endpoints of COVID-2019 vaccines:
the evidence we have versus the evidence we need
Vaccine developer Platform Preliminary
vaccine efficacy
Neutralizing
antibodies
T cell response
Moderna
(mRNA 1273)
mRNA  spike
100 ug day 0, 28
94.1% 18-55 yrs: 654
56 – 70 yrs: 878
> 71 yrs: 317
CD4 Th1 response
Low CD 8 response
Pfizer,BioNTech
(BNT 162b2)
mRNA  spike
30 ug day 0, 21
95% 18 – 55 yrs: 163
65 – 85 yrs: 206
ND
Oxford Astra
Zeneca
SSI
Adenovirus  spike
5 x 1010 viral particles
day 0,28
70.4 %
low dose 90%
18 – 55; 161; 193
55 – 69 ; 143; 144
>70; 150; 161
IFN gamma ELISpot T
cell responses
Gamaleya
Sputnik V
Adenovirus  spike
10 x 1010 viral particles
day 0, 21
91.4% 18 – 60 yrs; 46 CD4 Th1 & CD8 T cell
responses
Janssen Adenovirus  spike
5 x 1010 viral particles
day 0 single dose
18 – 55 ; 214
> 65 : 196
CD 4 Th1 & CD 8 cell
responses

8. Serology Tests available
• Antigen used: NP, Spike, RBD
• Antibodies detected: Total, IgG
• Types of assay:
• Binding assay
• Neutralizing assay
• Plaque Reduction Neutralization Test (PRNT) with live virus
• PRNT with Pseudo-virus
• ELISA with recombinant ACE 2 receptors & RBD

9. Plaque Reduction Neutralizing Test (PRNT)

10. Plaque Reduction Neutralization Test (PRNT)

11. Pseudo-virus

12. Genetically engineered
RBD & ACE 2

14. Titre Number
 100 11
91 – 100 7
81 – 90 9
71 – 80 9
61 – 70 11
51 – 60 16
41 – 50 26
31 – 40 41
21 – 30 60
11 – 20 80
>1 251
< 1 1919
TNP 18
Total negative 2271
Total Positive 552
Titre Number
 1000 2
 500 1
> 400 1
300 – 399 17
200 – 299 58
100 – 199 275
80 – 99 103
40 – 79 294
15 – 39 368
12 – 15 58
< 12 1120
< 3.5 1462
TNP 28
Total Negative 2582
Total Positive 1119
Total Antibodies against NCP IgG Antibodies against S1/S2
N = 2841 N = 3787

16. SARS CoV 2 S binding antibody response to Covishield
Population Baseline 28 days after dose 1 28 days after dose 2
GMT
(95% CI)
GMT
(95% CI)
GMT
(95% CI)
Overall N= 882
57.18
(52.8 62.0)
N = 817
8,386.46
(7758.6 9065.1)
N = 819
29,034.74
(22118.2 31086.7)
Dose interval
< 6 weeks (N = 481)
60.51
(54.1 67.7)
(N = 479)
8734.08
(7883.1 9676.9)
(N = 443)
22222.73
(20360.5 24,255.3)
6 – 8 weeks ( N = 137)
58.02
(N = 99)
7295.54
( N= 116)
24363.1
9 – 11 weeks ( N = 110)
48.79
(N = 87)
7492.98
(N = 106)
34754.1
> 12 weeks (N = 154)
52.98
(44.4 63.2)
(N = 152)
8618.17
(7195.4 10322.3)
(N = 154)
63181.59
(55180.1 72343.4)

19. Saadat S et al . Binding and Neutralization Antibody Titers
After a Single Vaccine Dose in Health Care Workers
Previously Infected With SARS-CoV-2. JAMA 2021

20. Muller L et al. Age dependent immune response to
Biontech/Pfizer BNT 162 b2 Covid 19 vaccination
• 176 volunteers [ 91 less than 60 yrs & 85 over 80 yrs of age]
• Vaccinated them and determined their immune response
• Binding antibodies
• Neutralizing antibodies
• After first & second dose
• 31.3% in the older group did not produce detectable Neutralizing
Antibodies vs 2.2 % in younger age group
• May require more frequent booster

22. 1. generated an isogenic Y501 SARS-CoV-2 on the genetic
background of the N501 clinical strain USA-WA1/2020,
2. Sera of 20 participants in the previously reported trial,1,2
drawn 2 or 4 weeks after immunization with two 30-μg
doses of BNT162b2 spaced three weeks apart, were
tested for neutralization of N501 and Y501 viruses by a
50% plaque reduction neutralization assay (PRNT50;
Figure 1).
3. The ratio of the 50% neutralization GMT of the sera
against the Y501 virus to that against the N501 virus was
1.46, indicating no reduction in neutralization activity
against the virus bearing the Y501 spike
Pfizer

23. Moderna

24. Therapeutic Monoclonal Antibody therapy
• Bamlanivimab
• Etesevimab
• Casirivimab
• Imdevimab

25. McMohan K et al. Correlates of protection against
SARS-CoV-2 in rhesus macaques.
Nature | Vol 590 | 25 February 2021
• Purified IgG from convalescent monkeys was injected into monkeys
• 250 mg/kg body wt; 25 mg/kg bw; 2.5 mg/kg bw, control
• All challenged with SARS Cov 2
• Only monkeys that received 250 mg/kg bw were fully protected
• Antibodies levels for full protection were
• Neutralizing antibodies = 50
• RBD ELISA titre = 100
• Anti spike IgG titre = 400
• Depletion of CD 8+ T cells in coalescent monkeys partially abrogated
protective efficacy of natural immunity against rechallenge
• Cellular immune response may contribute to protection

26. Lucas C et al. Delayed production of neutralizing
antibodies correlates with fatal COVID-19.
• 229 patients with full spectrum of Covid 19 disease from asymptomatic  severe
disease were included in the study
• Correlation was found between anti spike (S) IgG levels, length of hospitalization
and clinical parameters associated with worse clinical progression
• Although high anti S IgG correlated with worse disease severity, such correlation
was time dependent
• Deceased patients did not have higher overall immune response than discharged
patients, however they mounted a robust, yet delayed, response measured by
anti S, anti RBD and Nab levels compared to survivors
• Nab generation before 14 days of disease onset emerged as a key factor for
recovery
• Mortality in Covid 19 correlated with delayed kinetics of Neutralizing Antibodies