Anti-Spike, anti-Nucleocapsid and neutralizing antibodies in SARS-CoV-2 hospitalized patients and asymptomatic carriers

Using longitudinal plasma samples from thirty COVID-19 patients, we observed that virus-specific antibodies are detectable in 100% of patients two weeks after symptom onset. We also show that these patients produced variable levels of neutralizing antibodies which reached a plateau two weeks after symptom onset and then declined in the majority of patients. Furthermore, we report that neutralizing antibodies were undetectable in 56% (14/25) of asymptomatic carriers.

and caused a human pandemic of coronavirus disease 2019 . Among the four SARS-CoVkinetics of antibody detection is essential for the selection of commercial serological assays and the 48 interpretation of the results. Some manufacturers have decided to target the S1 and/or the S2

52
In order to accurately assess the time of seroconversion, we used 151 samples from 30 53 patients hospitalized at the Amiens University Hospital for a COVID-19 (see Supplementary Table 1) 54 to monitor the kinetics of detection of anti-S1, anti-S2, anti-RBD and anti-N antibodies with in-house 55 ELISAs. We observed that antibodies targeting the N protein and the RBD were the earliest to be 56 detected (Fig. 1a). Thirteen days post-symptom onset, 100% of patients had detectable antibodies to 57 both proteins. A similar profile was observed for anti-S2 antibodies but with a mean time lag of two 58 days. Antibodies to the S1 subunit were the last to be detected and remained undetectable for two 59 patients. High levels of anti-N and anti-RBD antibodies were detected in the large majority of samples 60 obtained fourteen days post-symptom onset whereas very heterogeneous levels of anti-S1 antibodies 61 were found in the same samples (Fig. 1b). The positive correlations between each ELISA are shown 62 in Extended Data Fig. 1. Significant differences were observed between intensive care versus non-63 intensive care patients for anti-S1, anti-S2 and anti-N antibody levels, from eight days post-symptom 64 onset (Extended Data Fig. 2a). A slight difference was observed for anti-N antibody levels according to Furthermore, plasmas from twelve patients that had previously been infected with other coronaviruses 75 (OC43 (n=5), 229E (n=4), NL63 (n=2) or HKU1 (n=1)) did not have any effect on SARS-CoV-2 76 pseudotype infectivity (Extended Data Fig. 4b and Supplementary Table 2). As expected, our results 77 demonstrate that the production of NAbs correlates with the production of antibodies targeting the S1, 78 S2 and RBD domains and we detected NAbs in all COVID-19 patients fifteen days post-symptom 79 onset (Fig. 1a). The NAb titers increase from one week post-symptom onset and reaches a plateau 80 one week after (Fig. 2a, 2b and Extended Data Fig. 3). However, the NAb titers reached were variable 81 between patients, 17% generated low levels of NAbs (40 ≤ titers < 160), 73% intermediate levels (160 82 ≤ titers < 1280) and 10% high levels (1280 ≤ titers) (Fig. 2a). Positive correlations between NAb titers 83 and anti-S1, anti-S2, anti-N or anti-RBD antibody levels, as well as white blood cells and lymphocytes 84 counts are shown in Extended Data Fig. 5. Significantly higher NAb titers were observed in patients 85 with severe forms (p=0.04) and in women (p=0.03) from 14 days post-symptoms onset (Extended 86 Data Fig. 6). In contrast, no significant difference was observed according to the age. We also had the 87 opportunity to monitor the presence of NAbs in late samples of twelve patients (≥40 days post-88 symptom onset) and we observed that the NAb titer dropped to low or undetectable level in most of 89 these samples ( Fig. 2b and Extended data Fig. 3).

90
Finally, we monitored the presence of NAbs in plasma samples from 25 asymptomatic carriers.

91
It is important to note that we could not establish when these patients had been infected since they 92 were asymptomatic but it probably occurred more than one week before sampling since they were 93 confirmed seropositive using commercial serological assays and our in-house ELISAs (Supplementary 94 All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

98
Commercial serological assays that are complementary to direct viral detection of the SARStime or earlier than IgM levels 4 . We also report that COVID-19 patients generate variable levels of  (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.  (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.   (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.
The copyright holder for this preprint this version posted May 18, 2020.   (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.
The copyright holder for this preprint this version posted May 18, 2020.

247
All rights reserved. No reuse allowed without permission.
(which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.
The copyright holder for this preprint this version posted May 18, 2020. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.
The copyright holder for this preprint this version posted May 18, 2020. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.
(which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.
(which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.
(which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.
The copyright holder for this preprint this version posted May 18, 2020. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.
(which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.