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. 2021 Dec 9:12:798859.
doi: 10.3389/fimmu.2021.798859. eCollection 2021.

SARS-CoV-2 Antibodies Are Persisting in Saliva for More Than 15 Months After Infection and Become Strongly Boosted After Vaccination

Yudi T Pinilla  1   2 , Constanze Heinzel  1   2 , Lena-Fabienne Caminada  1 , Douglas Consolaro  1   2 , Meral Esen  1   2   3   4 , Peter G Kremsner  1   2   3 , Jana Held  1   2   3 , Andrea Kreidenweiss  1   2   3 , Rolf Fendel  1   2   3
Affiliations

SARS-CoV-2 Antibodies Are Persisting in Saliva for More Than 15 Months After Infection and Become Strongly Boosted After Vaccination

Yudi T Pinilla et al. Front Immunol. .

Abstract

SARS-CoV-2 antibodies in saliva serve as first line of defense against the virus. They are present in the mucosa, more precisely in saliva, after a recovered infection and also following vaccination. We report here the antibody persistence in plasma and in saliva up to 15 months after mild COVID-19. The IgG antibody response was measured every two months in 72 participants using an established and validated in-house ELISA assay. In addition, the virus inhibitory activity of plasma antibodies was assessed in a surrogate virus neutralization test before and after vaccination. SARS-CoV-2-specific antibody concentrations remained stable in plasma and saliva and the response was strongly boosted after one dose COVID-19 vaccination.

Keywords: COVID-19; SARS-CoV-2; antibody; convalescent; mucosa; neutralization; saliva; vaccination.

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Conflict of interest statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Figures

Figure 1
Figure 1
SARS-CoV-2 RBD reactive IgG over a 15-month follow-up period. Samples were collected 5 times, bimonthly from 72 convalesced volunteers who had mild COVID-19. IgG kinetics are shown per individual (black line). Sampling time points (black dots) are given as days post symptom onset (PSO). Blue line: regression line. Red dotted line: Cut-off for positivity. (A) IgG (µg/ml) kinetics in plasma after COVID-19 convalescence. Slope of linear regression = -0.02, p = 0.2. (B) IgG (ng/ml) kinetics in saliva after COVID-19 convalescence. Slope of linear regression = 0.009, p = 0.7.
Figure 2
Figure 2
SARS-CoV-2 RBD reactive IgG after vaccination. Samples were collected of whom 42 became vaccinated during the study. IgG kinetics are shown per individual (black line). Sampling time points (black dots) are given as days post symptom onset (PSO). Blue line: Local Polynomial Regression. Red dotted line: Cut-off for positivity. (A) Plasma IgG (µg/ml) concentration per convalesced volunteer before (square) and after (triangle) one dose of COVID-19 vaccination. Day 0 represents the reported day of vaccination. Local Polynomial Regression, residual standard error: 1979. (B) Salivary IgG (ng/ml) concentration per convalescent volunteer before (square) and after (triangle) one dose of COVID-19 vaccination. Day 0 represents the reported day of vaccination. Local Polynomial Regression, residual standard error: 1354.
Figure 3
Figure 3
Neutralizing activity of plasma antibodies to SARS-CoV-2. (A) Inhibitory activity (%) (surrogate for virus neutralization) of plasma IgG assessed at first sampling (4 months after infection), before vaccination and after vaccination. Neutralization activity are shown per individual (black line). Red dotted line: Cut-off for positivity. (B) Correlation of neutralization activity (%) and plasma IgG concentration after one vaccination (Pearson correlation, r=0.70).
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