Skip to main content
NCBI home page
Elsevier - PMC COVID-19 Collection logoLink to Elsevier - PMC COVID-19 Collection
. 2021 Mar 5;558:13–21. doi: 10.1016/j.virol.2021.02.002

Characterization of neutralizing versus binding antibodies and memory B cells in COVID-19 recovered individuals from India

Kaustuv Nayak a,1, Kamalvishnu Gottimukkala a,1, Sanjeev Kumar a,1, Elluri Seetharami Reddy a,b,1, Venkata Viswanadh Edara c,d,e, Robert Kauffman c,d, Katharine Floyd c,d,e, Grace Mantus c,d, Deepali Savargaonkar f, Pawan Kumar Goel g, Satyam Arora h, Manju Rahi i, Carl W Davis c,j, Susanne Linderman c,d, Jens Wrammert c,d, Mehul S Suthar c,d,e, Rafi Ahmed c,j, Amit Sharma f,k, Kaja Murali-Krishna a,c,d,∗∗, Anmol Chandele a,∗
PMCID: PMC7934698  PMID: 33706207

Abstract

India is one of the most affected countries by COVID-19 pandemic; but little is understood regarding immune responses to SARS-CoV-2 in this region. Herein we examined SARS-CoV-2 neutralizing antibodies, IgG, IgM, IgA and memory B cells in COVID-19 recovered individual from India. While a vast majority of COVID-19 recovered individuals showed SARS-CoV-2 RBD-specific IgG, IgA and IgM antibodies (38/42, 90.47%; 21/42, 50%; 33/42, 78.57% respectively), only half of them had appreciable neutralizing antibody titers. RBD-specific IgG, but not IgA or IgM titers, correlated with neutralizing antibody titers and RBD-specific memory B cell frequencies. These findings have timely significance for identifying potential donors for plasma therapy using RBD-specific IgG assays as surrogate measurement for neutralizing antibodies in India. Further, this study provides useful information needed for designing large-scale studies towards understanding of inter-individual variation in immune memory to SARS CoV-2 natural infection for future vaccine evaluation and implementation efforts.

Keywords: SARS-CoV-2, COVID-19, Receptor binding domain, Neutralizing antibodies, Memory B cells, India

1. Introduction

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the virus responsible for the coronavirus disease 2019 (COVID-19) pandemic, emerged as a grave public health threat beginning in December 2019 (WHO, 2020), paralyzing daily lives and causing economic downturns in many parts of the world. Currently, India is one of the countries most affected with more than 10.6 million COVID-19 confirmed cases and 155,732 associated deaths as of February 16, 2021 (Ministry of Health and Family Welfare GoI, 2020).

Intense efforts are underway to develop vaccines and antiviral therapeutics (Al-Kassmy et al., 2020; Amanat and Krammer, 2020; Dagotto et al., 2020; Hashemian et al., 2020; Li and Kang, 2020; Malik et al., 2020; Nabil et al., 2020; Parvathaneni and Gupta, 2020; Verma et al., 2020). All these efforts require a detailed understanding of immune correlates of protection, formation of immune memory, and durability of these responses. Additionally, infusion of plasma derived from COVID-19 recovered individuals is being explored as a management strategy (Bloch, 2020; Dhanasekaran et al., 2020; Duan et al., 2020; Focosi et al., 2020; Rabelo-da-Ponte et al., 2020; Salazar et al., 2020; Shen et al., 2020; Ye et al., 2020; Ju et al., 2020) and its rate of success will be augmented with a better understanding of humoral immunity, immunoglobulin isotype usage and neutralizing activity following recovery from SARS-CoV-2 infection. Moreover, given that many of the SARS-CoV-2 neutralizing epitopes are located in the viral receptor binding domain (RBD) of the spike (S) protein (Barnes et al., 2020; Cao et al., 2007; Lan et al., 2020; Liu et al., 2020a; Mittal et al., 2020; Peterhoff et al., 2020; Wang et al., 2020a; Zost et al., 2020a, 2020b), it is important to evaluate the relationship between RBD-specific IgG titers and neutralizing antibody responses in recovered individuals from India.

In this study, we evaluated IgG, IgA, IgM, neutralizing antibodies and memory B cell responses in PCR-confirmed COVID-19 convalescent subjects. Our results show that while a vast majority (38/42, 90.47%) of COVID-19 recovered individuals developed SARS-CoV-2 RBD-specific IgG responses, we were able to detect appreciable levels of neutralizing antibody responses in only half of the convalescent subjects. Neutralizing responses correlated closely with RBD-specific IgG titers, but weakly with IgG titers measured against whole virus concentrate using a commercial Enzyme Linked Immunosorbant Assay (ELISA) kit. Taken together, these findings suggest that despite significant inter-individual variation in the RBD-specific IgG titers and neutralizing antibodies, RBD-specific IgG titers continue to serve as a valuable and robust surrogate measurement for neutralizing antibody responses. Our observations, that many individuals do not develop appreciable levels of neutralizing antibodies, not only provides a glimpse of humoral immune responses in COVID-19 recovered individuals from India, but also has timely implications for identifying potential plasma therapy donors using on RBD-specific IgG ELISA's in India where routine performance of neutralization assays remains a challenge.

2. Methods

2.1. Patient recruitment

COVID-19 recovered individuals were recruited at Shaheed Hasan Khan Mewati Government Medical College, Nuh, Haryana, India, Super Specialty Pediatric Hospital and Post Graduate Teaching Institute, Noida and ICMR-National Institute of Malaria Research, New Delhi. The Institutional ethical boards approved the study. Informed consent was obtained prior to inclusion in the study. All subjects (mean age 39.4 years, range 15–70 years) were SARS-CoV-2 PCR positive at the time of initial diagnosis, and were PCR negative when recruited for this study at 3.6–12 weeks post initial diagnosis (Table 1 ). Samples collected from healthy adult blood bank donors in the year 2018 are included as pre-pandemic controls.

Table 1.

COVID-19 recovered individuals characteristics (n = 42)a.

Age in years Mean (Range) 39.4 (15–70)
Males/Females 38/4
Days post PCR diagnosis Mean (Range) 47.3 (25–84)
Open in a new tab
a

COVID-19 recovered individuals were recruited at Shaheed Hasan Khan Mewati Government Medical College, Nuh, Haryana, India. Super Speciality Paediatric Hospital and Post Graduate Teaching Institute, Noida and ICMR-National Institute of Malaria Research, New Delhi. All subjects were SARS-CoV-2 PCR positive at the time of initial diagnosis and were PCR negative when recruited for this study at 4.8–11 weeks post initial diagnosis.

2.2. SARS-CoV-2 specific PCR

Nasopharyngeal and throat swabs were collected in viral transport medium (VTM) (HiMedia, #AL 167)) and transported to the testing laboratory maintaining cold chain. All the samples were screened by qRT-PCR assay as the standard operating procedures established by Indian Council of Medical Research (ICMR)-National Institute of Virology (NIV), Pune, India under the Government of India guidelines for COVID-19 diagnosis. (ICMR-NIV, 2020).

2.3. SARS-CoV-2 RBD-specific direct ELISA

The recombinant SARS-CoV-2 RDB gene was cloned, expressed, purified and ELISAs were performed as previously described (Suthar et al., 2020). Briefly, purified RBD was coated on MaxiSorp plates (Thermo Fisher, #439454) at a concentration of 1 μg/mL in 100 μL phosphate-buffered saline (PBS) at 4 °C overnight. The plates were washed extensively with PBS containing 0.05% Tween-20. Three-fold serially diluted plasma was added to the plates and incubated at room temperature for 1hr. After incubation, the plates were washed and the SARS-CoV-2 RBD specific IgG, IgM, IgA signals were detected by incubating with horseradish peroxidase (HRP) conjugated - anti-human IgG (Jackson ImmunoResearch Labs, #109-036-098), IgM (Jackson ImmunoResearch Labs, #109-036-129), or IgA (Jackson ImmunoResearch Labs, #109-036-011). Plates were then washed thoroughly and developed with o-phenylenediamine (OPD) substrate (Sigma, #P8787) in 0.05 M phosphate-citrate buffer (Sigma, #P4809) pH 5.0, containing with 0.012% hydrogen peroxide (Fisher Scientific, #18755) just before use. Absorbance was measured at 490 nm.

2.4. Enumeration of SARS-CoV-2 RBD-specific memory B cells

Purified RBD protein (100 μg) was labeled with Alexa Fluor 488 using microscale protein labeling kit (Life Technologies, #A30006) as per manufacturer's protocol. PBMC's were stained with RBD-Alexa Fluor 488 for 1 h at 4 °C, followed by washing with PBS containing 0.25% Fetal Bovine Serum (FBS), and incubation with efluor780 Fixable Viability (Live Dead) dye (Life Technologies, #65-0865-14) and anti-human CD3, CD19, CD27, CD38 and IgD antibodies (BD Biosciences) for 30 min. Cells were washed twice with FACS buffer and acquired on BD LSR Fortessa X20. Data was analyzed using FlowJo software 10. SARS-CoV-2 RBD-specific memory B cells were identified in cells positive for CD19, CD20, CD27 that were negative for IgD and CD3.

2.5. IgG ELISA for SARS-CoV-2 whole virus preparation

SARS-CoV-2 antigen specific IgG was detected using a commercially available assay (COVID-Kavach ELISA tests kit, Zydus diagnostics), which measures responses to antigen concentrated from gamma-irradiated SARS-CoV-2-infected tissue culture fluid as per the manufacturer's instructions (Chaudhuri et al., 2020; Sapkal et al., 2020).

2.6. SARS-CoV-2 neutralization assay

Neutralization titers to SARS-CoV-2 were determined as previously described (Suthar et al., 2020). Briefly infectious clone of the full-length mNeonGreen SARS-CoV-2 (2019-nCoV/USA_WA1/2020) was used to test heat-inactivated COVID-19 convalescent samples and healthy donor samples (pre-pandemic). Heat-inactivated serum was serially diluted three-fold in duplicate starting at a 1:20 dilution in a 96-well round-bottom plate and incubated between 750 FFU of SARS-CoV-2-mNG for 1 h at 37 °C. This antibody-virus mixture was transferred into the wells of a 96-well plate that had been seeded with Vero-E6 cells the previous day at a concentration of 2.5 × 104 cells/well. After 1 h, the antibody-virus inoculum was removed and 0.85% methylcellulose in 2% FBS containing DMEM was overlaid onto the cell monolayer. Cells were incubated at 37 °C for 24 h. Cells were washed three times with 1XPBS (Corning Cellgro) and fixed with 125 μl of 2% paraformaldehyde in PBS (Electron Microscopy Sciences) for 30 min. Following fixation, plates were washed twice with 1x PBS and imaged on an ELISPOT reader (CTL Analyzer). Foci were counted using Viridot (Katzelnick et al., 2018) (counted first under the “green light” setting followed by background subtraction under the “red light” setting). FRNT-mNG50 titers were calculated by non-linear regression analysis using the 4 PL sigmoidal dose curve equation on Prism 8 (Graphpad Software). Neutralization titers were calculated as 100% x [1- (average foci in duplicate wells incubated with the specimen) ÷ (average number of foci in the duplicate wells incubated at the highest dilution of the respective specimen).

2.7. Statistical analysis

Statistical analysis was performed using GraphPad prism 8.0 software. Non-parametric t-test (Mann-Whitney) was used to calculate the differences between groups. Non-parametric Spearman's correlation coefficient (r) was used to calculate correlation between groups. A p value of ≤0.05 was considered as significant.

3. Results

3.1. SARS-CoV-2 RBD-specific humoral immunity in COVID-19 recovered individuals

The demographic profile of COVID-19 recovered individuals recruited for this study is shown in Table 1. All subjects were at least 3.6 weeks past their initial SARS-CoV-2 positive diagnosis. RBD-specific ELISA curves for IgG, IgA and IgM at different dilutions of plasma in pre-pandemic healthy versus COVID-19 recovered individuals is shown in Fig. 1 . RBD-specific responses were highly elevated in COVID-19 recovered individuals as compared to pre-pandemic healthy controls (Fig. 1A,B,C, left versus middle panels). Titers of IgG, IgA and IgM in the COVID-19 recovered individuals showed substantial inter-individual variation (Fig. 1 A, B, C, right panel) - with IgG endpoint titers ranging from below detection to 24,484 (2000 ± 619); IgA titers from below detection to 5686 (386 ± 136) and IgM titers from below detection to 2958 (515 ± 90). Four individuals had undetectable RBD-specific IgG and IgA titers. One of these individuals was also below detection for IgM ( Table 2 ). Inter-individual heterogeneity was not related to the age of the individuals (Fig. 2 A) or the number of days that elapsed between PCR confirmation of infection and sample collection (Fig. 2B).

Fig. 1.

Fig. 1

Open in a new tab

Evaluation of SARS-CoV-2 RBD specific IgG, IgA and IgM antibody responses. (A) RBD-specific IgG, (B), RBD-specific IgA; (C), RBD-specific IgM. Left, pre-pandemic healthy (n-22), middle COVID-19 recovered (n = 42); right, endpoint titers. ELISA cutoff values are calculated using the average plus 3 standard deviations of the 22 healthy controls at 1:100 dilution (shown as a dotted line). The unpaired analysis was done using non-parametric Mann-Whitney-U test. p ≤ 0.05 was considered significant. Assay cutoff value is marked with dotted line.

Table 2.

Individual characteristics of the COVID-19 recovered subjects.

Subject number Age Gender (Male,M Female,F) Days Post PCR Diagnosis SARS CoV-2 RBD specific Immunoglobulin titersa
 SARS Cov-2 whole Virus specific IgG ELISA valuesb Neutralization titer (FRNT-mNG50)c
IgG IgM IgA
1 23 M 84 2220 565 220 26 39
2 22 F 84 354 283 <100 3 26
3 68 M 40 464 <100 <100 19 <20
4 35 M 51 4547 393 545 6 113
5 50 M 37 1354 301 275 7 81
6 29 M 34 <100 866 <100 <1.5 <20
7 27 M 34 422 104 450 <1.5 <20
8 25 M 34 222 1031 <100 26 <20
9 21 M 40 650 588 153 9 25
10 39 M 38 612 539 5686 12 23
11 46 M 38 2011 325 224 24 55
12 31 M 38 494 828 183 10 <20
13 20 M 41 944 274 <100 14 49
14 36 M 41 228 279 1614 <1.5 <20
15 34 M 44 282 302 <100 4 <20
16 70 M 44 1250 220 518 14 43
17 40 M 45 464 112 101 16 <20
18 32 M 41 867 381 399 <1.5 <20
19 57 M 45 1069 354 231 <1.5 <20
20 27 F 49 1935 528 <100 23 80
21 36 M 49 3156 355 593 28 166
22 24 M 45 <100 387 <100 <1.5 <20
23 55 F 45 <100 778 <100 <1.5 <20
24 15 M 45 212 496 <100 <1.5 <20
25 49 M 45 4183 2958 397 17 657
26 26 M 48 2352 <100 <100 16 48
27 54 F 54 1202 <100 182 15 49
28 53 M 52 799 197 417 12 <20
29 52 M 48 2611 249 157 23 46
30 45 M 62 1490 401 <100 15 50
31 52 M 56 10,127 421 437 21 434
32 26 M 47 <100 <100 <100 <1.5 <20
33 32 M 57 701 177 <100 14 <20
34 44 M 49 815 428 <100 20 <20
35 32 M 40 829 140 <100 6 29
36 44 M 42 4685 494 295 26 167
37 22 M 77 3954 764 690 24 209
38 49 M 25 24,484 2828 459 22 682
39 55 M 51 371 753 <100 17 <20
40 36 M 51 621 350 104 17 <20
41 60 M 51 156 459 <100 17 34
42 62 M 47 467 354 <100 6 <20
Open in a new tab
a

ELISA end point titre limit of detection is 100.

b

ELISA was performed with a commercial kit (Covid Kavach, Zydus) using 1:100 dilution of plasma as per by the manufacturer's recommendation. Assay cut off is 1.5.

c

Neutralization titres: Neutralization assay were performed using 3 fold dilution of plasma, starting at 1:20 up to 1:43,740. Limit of detection for FRNT-mNG50 is 20.

Fig. 2.

Fig. 2

Open in a new tab

Correlation of age and day post initial diagnosis of COVID-19 recovered individuals with SARS-CoV-2 IgG, IgM and IgA titers. (A). Age versus IgG (left, n = 42), IgA (middle, n = 42) or IgM (right, n = 42) titers. (B). Time post initial diagnosis versus IgG (left, n = 42), IgA (middle, n = 42) or IgM (right, n = 42) titers. Correlations were calculated by Spearman's correlation coefficient r. p ≤ 0.05 is considered significant. Note that none of the data sets above reached significant values of correlation.

3.2. SARS-CoV-2 specific neutralizing titers in COVID-19 recovered individuals

To assess plasma neutralizing titers from COVID-19 convalescent individuals, we performed a live virus neutralization assay using a focus-reduction neutralization mNeonGreen (FRNT-mNG) assay (Suthar et al., 2020). The neutralizing activity at different dilutions of plasma for pre-pandemic healthy individuals (Fig. 3 A) and COVID-19 recovered individuals is shown in (Fig. 3B). Fig. 3C shows FRNT-mNG50 titers calculated based on the plasma dilution that neutralized 50% of the virus. While all pre-pandemic healthy individuals had undetectable FRNT-mNG50 titers, only half of the COVID-19 recovered individuals showed 50% or more neutralization even at a 1:20 dilution of plasma. Similar to RBD-specific IgG titers, the FRNT-mNG50 titers were heterogeneous with the latter reaching titers as high as 682 ( Fig. 3C).

Fig. 3.

Fig. 3

Open in a new tab

Evaluation of SARS-CoV-2 neutralizing antibodies in COVID-19 recovered individuals. SARS-CoV-2 neutralizing activity at indicated dilutions of plasma is shown in pre-pandemic healthy (n = 22, in grey) (A) and in COVID-19 recovered individuals (n = 42, in blue) (B). Dotted line represents the plasma dilution that leads to 50% neutralization. (C) Scatter plot shows neutralization titers (FRNT-mNG50) in pre-pandemic healthy (n = 22) and COVID-19 recovered (n = 42) individuals. The unpaired analysis was done using non-parametric Mann-Whitney-U test. p ≤ 0.05 was considered significant. Limit of detection is marked with a dotted line.

Previous studies in other viral infections have shown that all three antibody isotypes (IgG, IgA and IgM) can potentially neutralize (Chua et al., 2017; Ejemel et al., 2020; Lizeng et al., 2004; Skountzou et al., 2014; Sterlin et al., 2020). We next determined if any correlation exists between SARS-CoV-2 neutralizing titers and RBD-specific IgG, IgA, IgM binding antibody titers. We observed a positive correlation (r = 0.83; p < 0.001) between SARS-CoV-2 neutralizing titers and RBD-specific IgG titers (Fig. 4 , left graph) but not with IgA ( Fig. 4 , middle graph) or IgM titers (Fig. 4 , right graph).

Fig. 4.

Fig. 4

Open in a new tab

Correlation analysis of SARS-CoV-2-specific antibody responses versus neutralization titers. Correlation analysis shows FRNT-mNG50 titers (x-axis) versus RBD-specific IgG (Left), IgA (middle) and IgM (right) titers on y-axis in COVID-19 recovered individuals (n = 42, blue dots). Correlation analysis was performed by log transformation of the endpoint ELISA titers followed by linear regression analysis. Dotted line on x-axis and y-axis indicate limit of detection. Correlations were calculated by Spearman's correlation coefficient r. p ≤ 0.05 was considered significant and indicated in the figure.

Plasma infusion therapy has recently been started in India as an intervention therapy for COVID-19. For this, plasma donors are being typically identified by the presence of IgG to SARS-CoV-2 by commercial ELISA tests (cdsco.gov.in, 2020). One of these tests detects IgG towards viral antigens concentrated from gamma-irradiated SARS-CoV-2-infected tissue culture fluid (Chaudhuri et al., 2020; Sapkal et al., 2020). It was therefore of interest to examine the correlation between neutralization titers and IgG responses measured using this test. We observed that, of the 42 COVID-19 recovered individuals tested, 33 were IgG positive whereas 9 were below the assay cut off (Fig. 5 A). Of the 9 individuals that were below cut off, 4 also tested negative by the RBD-specific IgG ELISA (Table 2). All of the samples from the pre-pandemic healthy individuals were below the limit of detection. As expected, the IgG values obtained by whole virus-based ELISA did not show as robust a correlation (r = 0.56) with neutralizing antibody titers (Fig. 5B) as compared to those observed with RBD-specific IgG titers (r = 0.83) (Fig. 4 , left graph).

Fig. 5.

Fig. 5

Open in a new tab

Correlation analysis of SARS-CoV-2 whole virus specific IgG versus neutralizing titers. (A). Scatter plots shows SARS-CoV-2 whole virus specific IgG measured using measured using commercial kit (Zydus diagnosis, Covid Kavach) in pre-pandemic healthy (n = 5) and COVID-19 recovered (n = 42). The unpaired analysis was done using non-parametric Mann-Whitney-U test. p ≤ 0.05 was considered significant. (B). Correlation analysis of SARS-CoV-2 whole virus antigen specific IgG ELISA kit values (y-axis) versus neutralizing titers (x-axis) in COVID-19 recovered individuals (n = 42). Correlations were calculated by Spearman's correlation coefficient r. p ≤ 0.05 was considered significant. Dotted line on x-axis indicate limit of detection and on y-axis assay cut off.

3.3. Characterization of RBD-specific memory B cells in COVID-19 recovered individuals

While circulating neutralizing antibodies help prevent re-infection by viruses, memory B cells allow for rapid production of new antibodies in case of re-infection. To address whether the COVID-19 recovered individuals generated memory B cells, we enumerated RBD-specific memory B cells using fluorescently conjugated RBD antigen. An example of the flow cytometric gating strategy and RBD staining among the gated memory B cells is shown in Fig. 6 A and B. Fig. 6C shows the frequency of RBD-specific memory B cells in a subset of the individuals where sufficient PBMCs were available. Though we found that there was substantial inter-individual variation in the frequency of SARS-CoV-2 RBD-specific memory B cells, their frequencies modestly correlated with RBD-specific IgG titers.

Fig. 6.

Fig. 6

Open in a new tab

SARS-CoV-2 RBD-specific memory B cell analysis in COVID-19 recovered individuals. (A) Gating strategy used to identify memory B cells. (B) SARS-CoV-2 RBD-specific memory B cells on gated total memory B cells that were CD19 positive, CD20 high, IgD negative and CD27 high is shown. (C) Frequency of RBD-specific memory B cells of the total memory B cells in the COVID-19 recovered individuals (n = 13). (D) Correlation analysis shows frequency of RBD-specific memory B cells (x-axis) and the RBD-specific IgG titers (y-axis) in COVID-19 recovered individuals.

4. Discussion

Our study provides a succinct analysis of humoral immunity and memory B cells in COVID-19 recovered individuals from India. We examined SARS-CoV-2 neutralizing antibodies, IgG, IgM, IgA and memory B cells in pre-pandemic healthy versus COVID-19 recovered individuals and further evaluated inter-individual variation and relation among these.

Our correlative analysis of RBD-specific IgG binding titers with neutralizing antibody titers and memory B cells corroborates with other studies (Abe et al., 2020; Vaisman-Mentesh et al., 2020; Nguyen-Contant et al., 2020; Tan et al., 2020; Wang et al., 2020b) and has important implications for not only identifying potential donors for plasma therapy but also for understanding humoral and cellular memory formed post COVID-19 recovery from individuals in India. Though current plasma therapy guidelines in India do not consider neutralizing antibody titers, United States Food and Drug Administration (FDA) guidelines recommend, when available, a neutralizing titer of 1:160 or 1:80 to be used for identifying potential plasma donors (FDA, 2020). Our correlation analysis shows that RBD-specific titers of more than 3668 can provide a suitable surrogate for identifying the individuals with neutralizing titers of above 1:160 and RBD-specific IgG titers 1926 for neutralizing titers of 1:80. Recently, in a randomized control trial, 235 COVID-19 patients across 39 clinical sites across India received convalescent plasma therapy to access the role of convalescent plasma in management of COVID-19 (Agarwal et al., 2020). This study did not find any association of reduction in progression to severe COVID-19 or mortality with administration of convalescent plasma. However, neutralizing antibody responses or RBD IgG responses were not tested in donor plasma. It is also unclear whether the timing of plasma therapy coincided with presence of the virus – both which has been demonstrated to be critical to reap clinical benefits of convalescent plasma therapy (Donato et al., 2021; Ray et al., 2020).

Our study raises important questions on formation of protective immune memory after recovering from COVID-19. Consistent with a previous study (Kalkan Yazici et al., 2020), we found that nearly half of the COVID-19 recovered individuals did not induce 50% neutralizing titers even at 1:20 dilution of plasma. This raises the question of whether these individuals with low neutralizing antibodies also differ in formation of cellular immune memory. Our data show that individuals with low neutralizing antibodies indeed had lower memory B cells. Given that T cells may also contribute to COVID-19 protection, studies are needed to understand whether these individuals may also differ in the generation of memory CD8 and CD4 T cells (Chen and John Wherry, 2020; Grifoni et al., 2020; Jesenak et al., 2020).

The reason why only half of the COVID-19 recovered individuals developed appreciable levels of neutralizing antibody titers requires further investigation. This may be related to inter-individual differences in human immune responses associated with the expected heterogeneity in initial viral inoculum (Welten et al., 2016), initial viral loads (Akondy et al., 2015; Arankalle et al., 2010; Reddy et al., 2014), incubation period (Hermesh et al., 2010), host genetic factors (Carter-Timofte et al., 2020; Hou et al., 2020; LoPresti et al., 2020) and disease severity (Seow et al., 2020; Kong et al., 2020; Liu et al., 2020b). This is consistent with previous studies that show relatively higher neutralizing antibodies in COVID-19 hospitalized patients during the acute febrile phase, or in recovered individuals that were previously hospitalized with severe COVID-19 disease (Kong et al., 2020; Liu et al., 2020b). It is noteworthy that the COVID-19 recovered individuals from our study had mild to moderate symptoms during the initial diagnosis and thus our study cannot substantiate whether a higher proportion of individuals may have shown appreciable neutralizing titers if they had more severe symptoms during the acute stage. In light of these studies, our findings warrant future studies to seek an understanding of whether the individuals that have generated low or no neutralizing antibodies, IgG titers or memory B cells past recovery will be protected if they were re-exposed to SARS-CoV-2 or a related virus.

Author contributions

Experimental work, data acquisition and analysis of data by K.N, K.G, S.K, E.S.R, V.V.E., K.F, R.K, S.L. C. D, J.W, M.S.S, and D.S. Clinical site coordination by D. S, P.K.G, S.A, A.S and M.R. Conceptualization and implementation by A.S, R.A, K.M, A.C. Manuscript writing by A.C and K.M. All authors contributed reviewing and editing the manuscript.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements

This research was supported in part by Indian Council of Medical Research VIR/COVID-19/02/2020/ECD-1 (A.C, K.M). K.N, E.S.R. are supported through Dengue Translational Research Consortia National Biopharma Mission BT/NBM099/02/18(A.C.); K.G. is supported through DBT grant BT/PR30260/MED/15/194/2018(A.C, K.M); S.K. is supported through DBT/Wellcome Trust India Alliance Early Career Fellowship grant IA/E/18/1/504307. We are thankful to Mr. Satendra Singh and Mr. Ajay Singh, ICGEB, New Delhi for technical support; Director, SSPH & PGTI, Noida and Director, SHKM Government Medical College, Nuh, Haryana for facilitating the study. We thank Dr. Vineet Menachery and Dr. Pei-Yong Shi for providing the SARS-CoV-2mNG for the neutralization assays.

References

  1. Abe K.T., Li Z., Samson R., Samavarchi-Tehrani P., Valcourt E.J., Wood H., Budylowski P., Dupuis A.P., 2nd, Girardin R.C., Rathod B., Wang J.H., Barrios-Rodiles M., Colwill K., McGeer A.J., Mubareka S., Gommerman J.L., Durocher Y., Ostrowski M., McDonough K.A., Drebot M.A., Drews S.J., Rini J.M., Gingras A.C. A simple protein-based surrogate neutralization assay for SARS-CoV-2. JCI Insight. 2020;5 doi: 10.1172/jci.insight.142362. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Agarwal A., Mukherjee A., Kumar G., Chatterjee P., Bhatnagar T., Malhotra P., Collaborators P.T. Convalescent plasma in the management of moderate covid-19 in adults in India: open label phase II multicentre randomised controlled trial (PLACID Trial) BMJ. 2020;371:m3939. doi: 10.1136/bmj.m3939. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Akondy R.S., Johnson P.L., Nakaya H.I., Edupuganti S., Mulligan M.J., Lawson B., Miller J.D., Pulendran B., Antia R., Ahmed R. Initial viral load determines the magnitude of the human CD8 T cell response to yellow fever vaccination. Proc. Natl. Acad. Sci. U. S. A. 2015;112:3050–3055. doi: 10.1073/pnas.1500475112. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Al-Kassmy J., Pedersen J., Kobinger G. 2020. Vaccine Candidates against Coronavirus Infections. Where Does COVID-19 Stand? Viruses 12. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Amanat F., Krammer F. SARS-CoV-2 vaccines: status report. Immunity. 2020;52:583–589. doi: 10.1016/j.immuni.2020.03.007. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Arankalle V.A., Lole K.S., Arya R.P., Tripathy A.S., Ramdasi A.Y., Chadha M.S., Sangle S.A., Kadam D.B. Role of host immune response and viral load in the differential outcome of pandemic H1N1 (2009) influenza virus infection in Indian patients. PloS One. 2010;5 doi: 10.1371/journal.pone.0013099. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Barnes C.O., West A.P., Jr., Huey-Tubman K.E., Hoffmann M.A.G., Sharaf N.G., Hoffman P.R., Koranda N., Gristick H.B., Gaebler C., Muecksch F., Lorenzi J.C.C., Finkin S., Hagglof T., Hurley A., Millard K.G., Weisblum Y., Schmidt F., Hatziioannou T., Bieniasz P.D., Caskey M., Robbiani D.F., Nussenzweig M.C., Bjorkman P.J. Structures of human antibodies bound to SARS-CoV-2 spike reveal common epitopes and recurrent features of antibodies. Cell. 2020;182:828–842. doi: 10.1016/j.cell.2020.06.025. e16. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Bloch E.M. Convalescent plasma to treat COVID-19. Blood. 2020;136:654–655. doi: 10.1182/blood.2020007714. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Cao W.C., Liu W., Zhang P.H., Zhang F., Richardus J.H. Disappearance of antibodies to SARS-associated coronavirus after recovery. N. Engl. J. Med. 2007;357:1162–1163. doi: 10.1056/NEJMc070348. [DOI] [PubMed] [Google Scholar]
  10. Carter-Timofte M.E., Jorgensen S.E., Freytag M.R., Thomsen M.M., Brinck Andersen N.S., Al-Mousawi A., Hait A.S., Mogensen T.H. Deciphering the role of host genetics in susceptibility to severe COVID-19. Front. Immunol. 2020;11:1606. doi: 10.3389/fimmu.2020.01606. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. cdscogovin . 2020. A Phase II, Open Label, Randomized Controlled Trial to Assess the Safety and Efficacy of Convalescent Plasma to Limit COVID-19 Associated Complications in Moderate Disease. [Google Scholar]
  12. Chaudhuri S.T.R., Kshetrapal P., Batra G., Shrivastava T., Desiraju K.B., Kang G., Bhatnagar S. Comparative evaluation of SARS-CoV-2 IgG assays in India. 2020. medRxiv preprint. [DOI] [PMC free article] [PubMed]
  13. Chen Z., John Wherry E. T cell responses in patients with COVID-19. Nat. Rev. Immunol. 2020;20:529–536. doi: 10.1038/s41577-020-0402-6. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Chua C.L., Sam I.C., Chiam C.W., Chan Y.F. The neutralizing role of IgM during early Chikungunya virus infection. PloS One. 2017;12 doi: 10.1371/journal.pone.0171989. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Dagotto G., Yu J., Barouch D.H. Approaches and challenges in SARS-CoV-2 vaccine development. Cell Host Microbe. 2020 doi: 10.1016/j.chom.2020.08.002. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Dhanasekaran S., Vajravelu L.K., Venkatesalu V. Risk-benefit analysis on the clinical significance of convalescent plasma therapy in the management of COVID-19. Postgrad. Med. 2020 doi: 10.1136/postgradmedj-2020-138056. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Donato M.L., Park S., Baker M., Korngold R., Morawski A., Geng X., Tan M., Ip A., Goldberg S., Rowley S.D., Chow K.F., Brown E., Zenreich J., McKiernan P., Buttner K., Ullrich A., Long L., Feinman R., Ricourt A., Kemp M., Vendivil M., Suh H.C., Balani B., Cicogna C., Sebti R., Al-Khan A., Sperber S.J., Desai S., Fanning S.L., Arad D., Go R.C., Tam E., Rose K., Sadikot S., Siegel D.S., Gutierrez M., Feldman T., Goy A., Pecora A., Biran N., Leslie L.A., Gillio A., Timmapuri S., Boonstra M.S., Singer S., Kaur S., Richards E., Perlin D.S. Clinical and laboratory evaluation of patients with SARS-CoV-2 pneumonia treated with high-titer convalescent plasma. JCI Insight. 2021 doi: 10.1172/jci.insight.143196. [DOI] [PMC free article] [PubMed] [Google Scholar]
  18. Duan K., Liu B., Li C., Zhang H., Yu T., Qu J., Zhou M., Chen L., Meng S., Hu Y., Peng C., Yuan M., Huang J., Wang Z., Yu J., Gao X., Wang D., Yu X., Li L., Zhang J., Wu X., Li B., Xu Y., Chen W., Peng Y., Hu Y., Lin L., Liu X., Huang S., Zhou Z., Zhang L., Wang Y., Zhang Z., Deng K., Xia Z., Gong Q., Zhang W., Zheng X., Liu Y., Yang H., Zhou D., Yu D., Hou J., Shi Z., Chen S., Chen Z., Zhang X., Yang X. Effectiveness of convalescent plasma therapy in severe COVID-19 patients. Proc. Natl. Acad. Sci. U. S. A. 2020;117:9490–9496. doi: 10.1073/pnas.2004168117. [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. Ejemel M., Li Q., Hou S., Schiller Z.A., Tree J.A., Wallace A., Amcheslavsky A., Kurt Yilmaz N., Buttigieg K.R., Elmore M.J., Godwin K., Coombes N., Toomey J.R., Schneider R., Ramchetty A.S., Close B.J., Chen D.Y., Conway H.L., Saeed M., Ganesa C., Carroll M.W., Cavacini L.A., Klempner M.S., Schiffer C.A., Wang Y. A cross-reactive human IgA monoclonal antibody blocks SARS-CoV-2 spike-ACE2 interaction. Nat. Commun. 2020;11:4198. doi: 10.1038/s41467-020-18058-8. [DOI] [PMC free article] [PubMed] [Google Scholar]
  20. Fda . 2020. Recommendations for Investigational COVID-19 Convalescent Plasma. [Google Scholar]
  21. Focosi D., Anderson A.O., Tang J.W., Tuccori M. Convalescent plasma therapy for COVID-19: state of the art. Clin. Microbiol. Rev. 2020;33 doi: 10.1128/CMR.00072-20. [DOI] [PMC free article] [PubMed] [Google Scholar]
  22. Grifoni A., Weiskopf D., Ramirez S.I., Mateus J., Dan J.M., Moderbacher C.R., Rawlings S.A., Sutherland A., Premkumar L., Jadi R.S., Marrama D., de Silva A.M., Frazier A., Carlin A.F., Greenbaum J.A., Peters B., Krammer F., Smith D.M., Crotty S., Sette A. Targets of T Cell responses to SARS-CoV-2 coronavirus in humans with COVID-19 disease and unexposed individuals. Cell. 2020;181:1489–1501 e15. doi: 10.1016/j.cell.2020.05.015. [DOI] [PMC free article] [PubMed] [Google Scholar]
  23. Hashemian S.M., Farhadi T., Velayati A.A. A review on remdesivir: a possible promising agent for the treatment of COVID-19. Drug Des. Dev. Ther. 2020;14:3215–3222. doi: 10.2147/DDDT.S261154. [DOI] [PMC free article] [PubMed] [Google Scholar]
  24. Hermesh T., Moltedo B., Lopez C.B., Moran T.M. Buying time-the immune system determinants of the incubation period to respiratory viruses. Viruses. 2010;2:2541–2558. doi: 10.3390/v2112541. [DOI] [PMC free article] [PubMed] [Google Scholar]
  25. Hou Y., Zhao J., Martin W., Kallianpur A., Chung M.K., Jehi L., Sharifi N., Erzurum S., Eng C., Cheng F. New insights into genetic susceptibility of COVID-19: an ACE2 and TMPRSS2 polymorphism analysis. BMC Med. 2020;18:216. doi: 10.1186/s12916-020-01673-z. [DOI] [PMC free article] [PubMed] [Google Scholar]
  26. ICMR-NIV . 2020. Standard Operating Procedure for Detection of 2019 Novel Coronavirus (2019-nCoV) in Suspected Human Cases by rRT-PCR : Confirmation Assay. [Google Scholar]
  27. Jesenak M., Brndiarova M., Urbancikova I., Rennerova Z., Vojtkova J., Bobcakova A., Ostro R., Banovcin P. Immune parameters and COVID-19 infection - associations with clinical severity and disease prognosis. Front Cell Infect Microbiol. 2020;10:364. doi: 10.3389/fcimb.2020.00364. [DOI] [PMC free article] [PubMed] [Google Scholar]
  28. Ju B., Zhang Q., Ge J., Wang R., Sun J., Ge X., Yu J., Shan S., Zhou B., Song S., Tang X., Yu J., Lan J., Yuan J., Wang H., Zhao J., Zhang S., Wang Y., Shi X., Liu L., Zhao J., Wang X., Zhang Z., Zhang L. Human neutralizing antibodies elicited by SARS-CoV-2 infection. Nature. 2020;584:115–119. doi: 10.1038/s41586-020-2380-z. [DOI] [PubMed] [Google Scholar]
  29. Kalkan Yazici M., Koc M.M., Cetin N.S., Karaaslan E., Okay G., Durdu B., Sumbul B., Doymaz M.Z. Discordance between serum neutralizing antibody titers and the recovery from COVID-19. J. Immunol. 2020;205:2719–2725. doi: 10.4049/jimmunol.2000840. [DOI] [PubMed] [Google Scholar]
  30. Katzelnick L.C., Coello Escoto A., McElvany B.D., Chavez C., Salje H., Luo W., Rodriguez-Barraquer I., Jarman R., Durbin A.P., Diehl S.A., Smith D.J., Whitehead S.S., Cummings D.A.T. Viridot: an automated virus plaque (immunofocus) counter for the measurement of serological neutralizing responses with application to dengue virus. PLoS Neglected Trop. Dis. 2018;12 doi: 10.1371/journal.pntd.0006862. [DOI] [PMC free article] [PubMed] [Google Scholar]
  31. Kong W.H., Zhao R., Zhou J.B., Wang F., Kong D.G., Sun J.B., Ruan Q.F., Liu M.Q. Serologic response to SARS-CoV-2 in COVID-19 patients with different severity. Virol. Sin. 2020 doi: 10.1007/s12250-020-00270-x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  32. Lan J., Ge J., Yu J., Shan S., Zhou H., Fan S., Zhang Q., Shi X., Wang Q., Zhang L., Wang X. Structure of the SARS-CoV-2 spike receptor-binding domain bound to the ACE2 receptor. Nature. 2020;581:215–220. doi: 10.1038/s41586-020-2180-5. [DOI] [PubMed] [Google Scholar]
  33. Li Q., Kang C. Progress in developing inhibitors of SARS-CoV-2 3C-like protease. Microorganisms. 2020;8 doi: 10.3390/microorganisms8081250. [DOI] [PMC free article] [PubMed] [Google Scholar]
  34. Liu L., Wang P., Nair M.S., Yu J., Rapp M., Wang Q., Luo Y., Chan J.F., Sahi V., Figueroa A., Guo X.V., Cerutti G., Bimela J., Gorman J., Zhou T., Chen Z., Yuen K.Y., Kwong P.D., Sodroski J.G., Yin M.T., Sheng Z., Huang Y., Shapiro L., Ho D.D. Potent neutralizing antibodies against multiple epitopes on SARS-CoV-2 spike. Nature. 2020;584:450–456. doi: 10.1038/s41586-020-2571-7. [DOI] [PubMed] [Google Scholar]
  35. Liu Z.L., Liu Y., Wan L.G., Xiang T.X., Le A.P., Liu P., Peiris M., Poon L.L.M., Zhang W. Antibody profiles in mild and severe cases of COVID-19. Clin. Chem. 2020;66:1102–1104. doi: 10.1093/clinchem/hvaa137. [DOI] [PMC free article] [PubMed] [Google Scholar]
  36. Lizeng Q., Nilsson C., Sourial S., Andersson S., Larsen O., Aaby P., Ehnlund M., Bjorling E. Potent neutralizing serum immunoglobulin A (IgA) in human immunodeficiency virus type 2-exposed IgG-seronegative individuals. J. Virol. 2004;78:7016–7022. doi: 10.1128/JVI.78.13.7016-7022.2004. [DOI] [PMC free article] [PubMed] [Google Scholar]
  37. LoPresti M., Beck D.B., Duggal P., Cummings D.A.T., Solomon B.D. The role of host genetic factors in coronavirus susceptibility: review of animal and systematic review of human literature. Am J Hum Genet doi. 2020 doi: 10.1016/j.ajhg.2020.08.007. [DOI] [PMC free article] [PubMed] [Google Scholar]
  38. Malik S., Gupta A., Zhong X., Rasmussen T.P., Manautou J.E., Bahal R. Emerging therapeutic modalities against COVID-19. Pharmaceuticals. 2020;13 doi: 10.3390/ph13080188. [DOI] [PMC free article] [PubMed] [Google Scholar]
  39. Ministry of Health and Family Welfare GoI . 2020. COVID-19 INDIA as on. [Google Scholar]
  40. Mittal A., Manjunath K., Ranjan R.K., Kaushik S., Kumar S., Verma V. COVID-19 pandemic: insights into structure, function, and hACE2 receptor recognition by SARS-CoV-2. PLoS Pathog. 2020;16 doi: 10.1371/journal.ppat.1008762. [DOI] [PMC free article] [PubMed] [Google Scholar]
  41. Nabil A., Uto K., Elshemy M.M., Soliman R., Hassan A.A., Ebara M., Shiha G. Current coronavirus (SARS-CoV-2) epidemiological, diagnostic and therapeutic approaches: an updated review until June 2020. EXCLI J. 2020;19:992–1016. doi: 10.17179/excli2020-2554. [DOI] [PMC free article] [PubMed] [Google Scholar]
  42. Nguyen-Contant P., Embong A.K., Kanagaiah P., Chaves F.A., Yang H., Branche A.R., Topham D.J., Sangster M.Y. S protein-reactive IgG and memory B cell production after human SARS-CoV-2 infection includes broad reactivity to the S2 subunit. mBio. 2020;11 doi: 10.1128/mBio.01991-20. [DOI] [PMC free article] [PubMed] [Google Scholar]
  43. Parvathaneni V., Gupta V. Utilizing drug repurposing against COVID-19 - efficacy, limitations, and challenges. Life Sci. 2020 doi: 10.1016/j.lfs.2020.118275:118275. [DOI] [PMC free article] [PubMed] [Google Scholar]
  44. Peterhoff D., Gluck V., Vogel M., Schuster P., Schutz A., Neubert P., Albert V., Frisch S., Kiessling M., Pervan P., Werner M., Ritter N., Babl L., Deichner M., Hanses F., Lubnow M., Muller T., Lunz D., Hitzenbichler F., Audebert F., Hahnel V., Offner R., Muller M., Schmid S., Burkhardt R., Gluck T., Koller M., Niller H.H., Graf B., Salzberger B., Wenzel J.J., Jantsch J., Gessner A., Schmidt B., Wagner R. A highly specific and sensitive serological assay detects SARS-CoV-2 antibody levels in COVID-19 patients that correlate with neutralization. Infection. 2020 doi: 10.1007/s15010-020-01503-7. [DOI] [PMC free article] [PubMed] [Google Scholar]
  45. Rabelo-da-Ponte F.D., Silvello D., Scherer J.N., Ayala A.R., Klamt F. Convalescent plasma therapy on patients with severe or life-threatening COVID-19: a metadata analysis. J. Infect. Dis. 2020 doi: 10.1093/infdis/jiaa509. [DOI] [PMC free article] [PubMed] [Google Scholar]
  46. Ray Yogiraj, P S.R., Bandopadhyay Purbita, D'Rozario Ranit, Sarif Jafar, Lahiri Abhishake, Bhowmik Debaleena, Srinivasa Vasudevan Janani, Maurya Ranjeet, Kanakan Akshay, Sharma Sachin, Kumar Manish, Singh Praveen, Roy Rammohan, Chaudhury Kausik, Maiti Rajsekhar, Bagchi Saugata, Maiti Ayan, Perwez Masoom, Mondal Abhinandan, Tewari Avinash, Mandal Samik, Roy Arpan, Saha Moumita, Biswas Durba, Maiti Chikam, Chakraborty Sayantan, Sharma Sarkar Biswanath, Haldar Anima, Saha Bibhuti, Sengupta Shantanu, Pandey Rajesh, Chatterjee Shilpak, Bhattacharya Prasun, Paul Sandip, Ganguly Dipyaman. Clinical and immunological benefits of convalescent plasma therapy in severe COVID-19: insights from a single center open label randomised control trial. 2020. MedRxiv. [DOI]
  47. Reddy V., Mani R.S., Desai A., Ravi V. Correlation of plasma viral loads and presence of Chikungunya IgM antibodies with cytokine/chemokine levels during acute Chikungunya virus infection. J. Med. Virol. 2014;86:1393–1401. doi: 10.1002/jmv.23875. [DOI] [PubMed] [Google Scholar]
  48. Salazar E., Christensen P.A., Graviss E.A., Nguyen D.T., Castillo B., Chen J., Lopez B.V., Eagar T.N., Yi X., Zhao P., Rogers J., Shehabeldin A., Joseph D., Leveque C., Olsen R.J., Bernard D.W., Gollihar J., Musser J.M. Treatment of COVID-19 patients with convalescent plasma reveals a signal of significantly decreased mortality. Am. J. Pathol. 2020 doi: 10.1016/j.ajpath.2020.08.001. [DOI] [PMC free article] [PubMed] [Google Scholar]
  49. Sapkal G., Shete-Aich A., Jain R., Yadav P.D., Sarkale P., Lakra R., Baradkar S., Deshpande G.R., Mali D., Tilekar B.N., Majumdar T., Kaushal H., Gurav Y., Gupta N., Mohandas S., Deshpande K., Kaduskar O., Salve M., Patil S., Gaikwad S., Sugunan A.P., Ashok M., Giri S., Shastri J., Abraham P., Gangakhedkar R.R., Covid Support Team, Pawar S., Patshute S., Salve V., Natarajan V., Marwah V., Malhotra B., Jain A., Sathe P., More R., Khedekar R., Suryawanshi D., Kalele K., Kumar A, Upadhyaya C.P., Waghmare A., Gawande P., Gopale S., Acharya M., Holeppanavar M., Thorat S., Chopade G., Vidhate S., Khutwad K., Phagiwala D., Bhanarkar S., Rakhe A., Salvi V., Dhaigude S., Ciyona Development of indigenous IgG ELISA for the detection of anti-SARS-CoV-2 IgG. Indian J. Med. Res. 2020;151:444–449. doi: 10.4103/ijmr.IJMR_2232_20. [DOI] [PMC free article] [PubMed] [Google Scholar]
  50. Seow Jeffrey, G C., Merrick Blair, Acors Sam, Kathryn J., Steel A., Oliver Hemmings, O'Bryne Aoife, Kouphou Neophytos, Pickering Suzanne, Galao Rui, Betancor Gilberto, Wilson Harry D., Signell Adrian W., Winstone Helena, Kerridge Claire, Temperton Nigel, Snell Luke, Bisnauthsing Karen, Moore Amelia, Green Adrian, Martinez Lauren, Stokes Brielle, Honey Johanna, Izquierdo-Barras Alba, Gill Arbane, Patel Amita, OConnell Lorcan, Hara Geraldine O., MacMahon Eithne, Sam Douthwaite, Nebbia Gaia, Batra Rahul, Martinez-Nunez Rocio, Edgeworth Jonathan D., Neil Stuart J.D., Malim Michael H., Doores Katie. Longitudinal evaluation and decline of antibody responses in SARS-CoV-2 infection. 2020. medRxiv. [DOI]
  51. Shen C., Wang Z., Zhao F., Yang Y., Li J., Yuan J., Wang F., Li D., Yang M., Xing L., Wei J., Xiao H., Yang Y., Qu J., Qing L., Chen L., Xu Z., Peng L., Li Y., Zheng H., Chen F., Huang K., Jiang Y., Liu D., Zhang Z., Liu Y., Liu L. Treatment of 5 critically ill patients with COVID-19 with convalescent plasma. J. Am. Med. Assoc. 2020 doi: 10.1001/jama.2020.4783. [DOI] [PMC free article] [PubMed] [Google Scholar]
  52. Skountzou I., Satyabhama L., Stavropoulou A., Ashraf Z., Esser E.S., Vassilieva E., Koutsonanos D., Compans R., Jacob J. Influenza virus-specific neutralizing IgM antibodies persist for a lifetime. Clin. Vaccine Immunol. 2014;21:1481–1489. doi: 10.1128/CVI.00374-14. [DOI] [PMC free article] [PubMed] [Google Scholar]
  53. Sterlin D.M.A., Miyara M., Mohr A., Anna F., Claer L., Quentric P., Fadlallah J., Ghillani P., Gunn C., Hockett R., Mudumba S., Guihot A., Luyt C.E., Mayaux J., Beurton A., Fourati S., Lacorte J.M., Yssel H., Parizot C., Dorgham K., Charneau P., Amoura Z., Gorochov G. IgA dominates the early neutralizing antibody response to SARS-CoV-2. 2020. medRxiv. [DOI] [PMC free article] [PubMed]
  54. Suthar M.S., Zimmerman M., Kauffman R., Mantus G., Linderman S., Vanderheiden A., Nyhoff L., Davis C., Adekunle S., Affer M., Sherman M., Reynolds S., Verkerke H., Alter D.N., Guarner J., Bryksin J., Horwath M., Arthur C., Saakadze N., Smith G.H., Edupuganti S., Scherer E.M., Hellmeister K., Cheng A., Morales J.A., Neish A.S., Stowell S.R., Frank F., Ortlund E., Anderson E., Menachery V., Rouphael N., Metha A., Stephens D.S., Ahmed R., Roback J., Wrammert J. Rapid generation of neutralizing antibody responses in COVID-19 patients. medRxiv. 2020 doi: 10.1101/2020.05.03.20084442. [DOI] [PMC free article] [PubMed] [Google Scholar]
  55. Tan C.W., Chia W.N., Qin X., Liu P., Chen M.I., Tiu C., Hu Z., Chen V.C., Young B.E., Sia W.R., Tan Y.J., Foo R., Yi Y., Lye D.C., Anderson D.E., Wang L.F. A SARS-CoV-2 surrogate virus neutralization test based on antibody-mediated blockage of ACE2-spike protein-protein interaction. Nat. Biotechnol. 2020;38:1073–1078. doi: 10.1038/s41587-020-0631-z. [DOI] [PubMed] [Google Scholar]
  56. Vaisman-Mentesh Anna, D Y., Tur-Kaspa Ran, Markovitch Dana, Kournos Tatiana, Dicker Dror, Wine Yariv. SARS-CoV-2 specific memory B cells frequency in recovered patient remains stable while antibodies decay over time. 2020. medRxiv. [DOI]
  57. Verma H.K., Merchant N., Verma M.K., Kuru C.I., Singh A.N., Ulucan F., Verma P., Bhattacharya A., Bhaskar L. Current updates on the European and WHO registered clinical trials of coronavirus disease 2019 (COVID-19) Biomed. J. 2020 doi: 10.1016/j.bj.2020.07.008. [DOI] [PMC free article] [PubMed] [Google Scholar]
  58. Wang Q., Zhang Y., Wu L., Niu S., Song C., Zhang Z., Lu G., Qiao C., Hu Y., Yuen K.Y., Wang Q., Zhou H., Yan J., Qi J. Structural and functional basis of SARS-CoV-2 entry by using human ACE2. Cell. 2020;181:894–904 e9. doi: 10.1016/j.cell.2020.03.045. [DOI] [PMC free article] [PubMed] [Google Scholar]
  59. Wang Y.Z.L., Sang L., Ye F., Ruan S., Zhong B., Song T., Alshukairi A.N., Chen R., Zhang Z., Gan M., Zhu A., Huang Y., Luo L., Mok C.K.P., Al Gethamy M.M., Tan H., Li Z., Huang X., Li F., Sun J., Zhang Y., Wen L., Li Y., Chen Z., Zhuang Z., Zhuo J., Chen C., Kuang L., Wang J., Lv H., Jiang Y., Li M., Lin Y., Deng Y., Tang L., Liang J., Huang J., Perlman S., Zhong N., Zhao J., Malik Peiris J.S., Li Y., Zhao J. Kinetics of viral load and antibody response in relation to COVID-19 severity. J. Clin. Invest. 2020;130:5235–5244. doi: 10.1172/JCI138759. [DOI] [PMC free article] [PubMed] [Google Scholar]
  60. Welten S.P.M., Redeker A., Toes R.E.M., Arens R. Viral persistence induces antibody inflation without altering antibody avidity. J. Virol. 2016;90:4402–4411. doi: 10.1128/JVI.03177-15. [DOI] [PMC free article] [PubMed] [Google Scholar]
  61. WHO . 2020. Timeline: WHO's COVID-19 Response. [Google Scholar]
  62. Ye M., Fu D., Ren Y., Wang F., Wang D., Zhang F., Xia X., Lv T. Treatment with convalescent plasma for COVID-19 patients in Wuhan, China. J. Med. Virol. 2020 doi: 10.1002/jmv.25882. [DOI] [PMC free article] [PubMed] [Google Scholar]
  63. Zost S.J., Gilchuk P., Case J.B., Binshtein E., Chen R.E., Reidy J.X., Trivette A., Nargi R.S., Sutton R.E., Suryadevara N., Williamson L.E., Chen E.C., Jones T., Day S., Myers L., Hassan A.O., Kafai N.M., Winkler E.S., Fox J.M., Steinhardt J.J., Ren K., Loo Y.M., Kallewaard N.L., Martinez D.R., Schafer A., Gralinski L.E., Baric R.S., Thackray L.B., Diamond M.S., Carnahan R.H., Crowe J.E. Potently neutralizing human antibodies that block SARS-CoV-2 receptor binding and protect animals. bioRxiv. 2020 doi: 10.1101/2020.05.22.111005. [DOI] [Google Scholar]
  64. Zost S.J., Gilchuk P., Chen R.E., Case J.B., Reidy J.X., Trivette A., Nargi R.S., Sutton R.E., Suryadevara N., Chen E.C., Binshtein E., Shrihari S., Ostrowski M., Chu H.Y., Didier J.E., MacRenaris K.W., Jones T., Day S., Myers L., Eun-Hyung Lee F., Nguyen D.C., Sanz I., Martinez D.R., Rothlauf P.W., Bloyet L.M., Whelan S.P.J., Baric R.S., Thackray L.B., Diamond M.S., Carnahan R.H., Crowe J.E., Jr. Rapid isolation and profiling of a diverse panel of human monoclonal antibodies targeting the SARS-CoV-2 spike protein. Nat. Med. 2020 doi: 10.1038/s41591-020-0998-x. [DOI] [PMC free article] [PubMed] [Google Scholar]

Articles from Virology are provided here courtesy of Elsevier

RESOURCES