Longitudinal Dynamics of the Neutralizing Antibody Response to Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Infection

Abstract

Background: Coronavirus disease 2019 (COVID-19) is a global pandemic with no licensed vaccine or specific antiviral agents for therapy. Little is known about the longitudinal dynamics of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-specific neutralizing antibodies (NAbs) in patients with COVID-19.

Methods: Blood samples (n = 173) were collected from 30 patients with COVID-19 over a 3-month period after symptom onset and analyzed for SARS-CoV-2-specific NAbs using the lentiviral pseudotype assay, coincident with the levels of IgG and proinflammatory cytokines.

Results: SARS-CoV-2-specific NAb titers were low for the first 7-10 days after symptom onset and increased after 2-3 weeks. The median peak time for NAbs was 33 days (interquartile range [IQR], 24-59 days) after symptom onset. NAb titers in 93.3% (28/30) of the patients declined gradually over the 3-month study period, with a median decrease of 34.8% (IQR, 19.6-42.4%). NAb titers increased over time in parallel with the rise in immunoglobulin G (IgG) antibody levels, correlating well at week 3 (r = 0.41, P < .05). The NAb titers also demonstrated a significant positive correlation with levels of plasma proinflammatory cytokines, including stem cell factor (SCF), TNF-related apoptosis-inducing ligand (TRAIL), and macrophage colony-stimulating factor (M-CSF).

Conclusions: These data provide useful information regarding dynamic changes in NAbs in patients with COVID-19 during the acute and convalescent phases.

Keywords: COVID-19; SARS-CoV-2; longitudinal dynamics; neutralizing antibodies; serological immune response.

Figure 1.

Analysis of the plasma response to SARS-CoV-2 infection. A, Sera from 5 convalescent patients with COVID-19 neutralized the SARS-CoV-2 pseudovirus. A serum sample from a healthy individual served as the negative control. The assay was performed in triplicate, and the median percentage of neutralization is shown. B, SARS-CoV-2 NAb titers of 20 plasma samples from convalescent patients with COVID-19 and 10 plasma samples from healthy donors. C, NAbs against VSVG, SARS-CoV, and SARS-CoV-2 pseudovirus in the sera from 30 convalescent patients with COVID-19. Abbreviations: COVID-19, coronavirus disease 2019; F, female; ID50, 50% inhibitory dose; M, male; NAb, neutralizing antibody; SARS-CoV, severe acute respiratory syndrome coronavirus; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2; VSVG, vesicular stomatitis virus G.

Figure 2.

Dynamic changes in NAbs against SARS-CoV-2. A, Kinetics of SARS-CoV-2 NAb levels in 30 patients with COVID-19. B, Number of patients experiencing peak NAb levels during hospitalization or after discharge. Follow-up point 1 represents the follow-up study conducted on 2 April while follow-up point 2 represents the follow-up study conducted on 8 May 2020. C, Peak NAb levels in the patients. D, Comparison of peak NAb levels between patients with COVID-19 experiencing peak NAb levels during hospitalization and patients with COVID-19 experiencing peak NAb levels after discharge. Abbreviations: COVID-19, coronavirus disease 2019; F, female; ID50, 50% inhibitory dose; M, male; NAb, neutralizing antibody; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.

Figure 3.

Decrease in NAb levels in patients with COVID-19. A, Comparison of NAb levels between the peak point and the follow-up time point 2. B, Percentage decrease in NAbs in patients with COVID-19. Abbreviations: COVID-19, coronavirus disease 2019; ID50, 50% inhibitory dose; NAb, neutralizing antibody; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.

Figure 4.

Correlation between the dynamics of NAb and virus-specific IgG levels. A, Kinetics of NAb and IgG levels in 6 patients. Plasma samples were collected at different time points after symptom onset. B, A total of 152 serum samples were grouped by time of collection after symptom onset; correlations were analyzed between NAb levels and IgG levels in each group. C, Correlations between NAb levels and IgG levels from serum samples collected 3 weeks after symptom onset. Abbreviations: F, female; ID50, 50% inhibitory dose; IgG, immunoglobulin G; M, male; NAb, neutralizing antibody.

Figure 5.

A–C, Correlation between peak NAb levels and cytokines in sera. Serum samples with the highest NAb levels for all individuals were collected during hospitalization. Cytokine or levels were measured using the Bio-Plex Human Cytokine Screening Panel (48-Plex no. 12007283; Bio-Rad) on a Luminex 200 (Luminex Multiplexing Instrument, Merck Millipore), following the manufacturer’s instructions. Pearson’s correlation was used to analyze differences between NAb levels and cytokine levels. Abbreviations: ID50, 50% inhibitory dose; M-CSF, macrophage colony-stimulating factor; NAb, neutralizing antibody; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2; SCF, stem cell factor; TRAIL, tumor necrosis factor (TNF)–related apoptosis-inducing ligand.