key: cord-0848358-jknbwvpc authors: MARTINUZZI, Emanuela; BENZAQUEN, Jonathan; GUERIN, Olivier; LEROY, Sylvie; SIMON, Thomas; ILIE, Marius; HOFMAN, Véronique; ALLEGRA, Maryline; TANGA, Virginie; MICHEL, Emeline; BOUTROS, Jacques; MANIEL, Charlotte; SICARD, Antoine; GLAICHENHAUS, Nicolas; CZERKINSKY, Cecil; BLANCOU, Philippe; HOFMAN, Paul; MARQUETTE, Charles H. title: A Single Dose of BNT162b2 mRNA Vaccine Induces Airway Immunity in SARS-CoV-2 Naive and recovered COVID-19 subjects date: 2022-05-17 journal: Clin Infect Dis DOI: 10.1093/cid/ciac378 sha: 5326d0e08904be9e67457809584682aef2f735e1 doc_id: 848358 cord_uid: jknbwvpc BACKGROUND: Mucosal antibodies can prevent virus entry and replication in mucosal epithelial cells and hence virus shedding. Parenteral booster injection of a vaccine against a mucosal pathogen promotes stronger mucosal immune responses following prior mucosal infection compared to injections of a parenteral vaccine in a mucosally naive subject. We investigated whether this was also the case for the BNT162b2 COVID-19 mRNA vaccine. METHODS: Twenty recovered COVID-19 subjects (RCS) and 23 SARS-CoV-2 naive subjects were vaccinated with respectively one and two doses of the BNT162b2 COVID-19 vaccine. Nasal Epithelial Lining Fluid (NELF) and plasma were collected before and after vaccination and assessed for Immunoglobulin (Ig)G and IgA antibody levels to Spike and for their ability to neutralize binding of Spike to ACE-2 receptor. Blood was analyzed one week after vaccination for the number of Spike-specific Antibody Secreting Cells (ASCs) with a mucosal tropism. RESULTS: All RCS had both nasal and blood SARS-CoV-2 specific antibodies at least 90 days after initial diagnosis. In RCS, a single dose of vaccine amplified pre-existing Spike-specific IgG and IgA antibody responses in both NELF and blood against both vaccine homologous and variant strains, including delta. These responses were associated with Spike-specific IgG and IgA ASCs with a mucosal tropism in blood. Nasal IgA and IgG antibody responses were lower in magnitude in SARS-CoV-2 naive subjects after two vaccine doses compared to RCS after one dose. CONCLUSION: Mucosal immune response to the SARS-CoV-2 Spike protein is higher in RCS after a single vaccine dose compared to SARS-CoV-2 naive subjects after two doses. r d'Azur, r d'Azur, Nice, France Amid the surge of variants of concern, most COVID-19 vaccines are highly effective 2 against hospitalization and death caused by a variety of SARS-CoV-2 strains (1-3). 3 Early studies performed before the emergence of the delta variant showed that 4 individuals who were fully vaccinated with an mRNA vaccine were less likely than 5 unvaccinated persons to be infected with SARS-CoV-2 or to transmit it to others (4, infections still transmit SARS-CoV-2, including to fully vaccinated contacts (6) . 9 Therefore, the risk of breakthrough infection in fully vaccinated people cannot be 10 eliminated as long as there is continued transmission of the virus. Protection from severe forms of COVID-19 in fully vaccinated adults is mediated 12 at least in part by SARS-CoV-2-specific antibodies as demonstrated by the transfer 13 of plasma from recovered COVID-19 subjects (RCS) to recently infected subjects (7). 14 However, the immune mechanisms that prevent carriage and shedding of SARS- 15 CoV-2 remain to be elucidated. Lessons drawn from other mucosal pathogens 16 suggest that mucosal antibodies and especially secretory immunoglobulin A (sIgA) 17 can efficiently block transmission of respiratory viruses (8). Relevant to this issue, 18 SARS-CoV-2-specific humoral responses are dominated by IgA and peripheral 19 expansion of IgA ASCs with a mucosal homing potential occurs shortly after disease 20 onset (9) . Further, sIgA are substantially more potent than bone marrow-derived 21 serum monomeric IgA and IgG at neutralizing SARS-CoV-2 (10). Spike-specific IgA 22 induced by mRNA COVID-19 vaccines are detected in SARS-CoV-2 naive 23 individuals in plasma (10), milk (12) , saliva (13) and nasal fluids (14) as early as two 24 weeks after vaccination and for up to 6 months. A dominant concept in vaccinology is that mucosal immunity is more efficiently 26 induced by mucosal, e.g. nasal or oral, administration of vaccines than by parenteral 27 injection, and that mucosal immune memory wanes more rapidly than systemic 28 immune memory (11, 12). On a related topic, we and others have shown that a single IgG (or IgA) measured using the V-PLEX® Isotyping Panel 1 Human/NHP Kit. 3 Plasma and NELF were diluted 100-fold and 10-fold respectively before being 4 analyzed by immunoassay. Data were acquired on the V-PLEX® Sector Imager 2400 5 plate reader and analyzed using Discovery Workbench 3·0 software. Serial 4-fold 6 dilutions of the standards were run to generate a 7-standard curve, and the diluent where they are no longer detectable after 2 weeks. While all ASCs express CD38, a 33 subpopulation co-express tissue-specific homing receptors, such as the integrin which preferentially directs these ASCs to mucosal sites. Thus, the frequency 1 and characteristics of blood ASCs provide a very early estimate of the nature and 2 intensity of a humoral immune response to any vaccine. Here, we used a modified 3 ELISPOT assay to measure the proportion of ASCs producing Spike-specific IgG and 4 IgA with a mucosal tropism (19). Briefly, we incubated 5 ml of blood cells with 5 magnetic beads (Dynabeads Pan Mouse IgG, Invitrogen) coated with monoclonal 6 Biolegend) or β7 integrin (clone antibodies (mAbs) to either CD38 (clone HB-7, 7 FIB504, BD Bioscience). We then applied a magnetic field to obtain cell suspensions 8 enriched for either CD38 + or β7 + cells. To detect ASCs secreting IgG or IgA to Spike, 9 we coated the wells of ELISPOT with purified Spike (Sino Biological Europe GmbH) We enrolled SARS-CoV-2 naive seronegative subjects (n=23) and RCS (n=20) who 31 had been infected with SARS-CoV-2 before the emergence of the delta variant and. Subjects in the two groups did not differ in age, gender, Body Mass Index (BMI), and total number of blood leukocytes, lymphocytes and neutrophils (Supplementary Table 1 1). 2 Before vaccination, IgA and IgG to Spike and RBD were readily detectable in proportion of β7 + cells among CD38 + was higher in the first group compared to the 2 second one, indicating that prior mucosal exposure through natural infection by 3 In keeping with our initial hypothesis, we found that the levels of Spike-specific IgG 7 and IgA in NELF, the proportion of responders and the ability of nasal antibodies to 8 inhibit the binding of Spike to ACE-2 were higher among RCS given a single dose of 9 BNT162b2 mRNA vaccine than in SARS-CoV-2 naive individuals after receiving two 10 doses. Further, the proportion of ASCs with a mucosal tropism was higher in RCS 11 than in naive subjects. did not appear to differ between the two groups while receptor binding inhibitory 25 antibody activity was higher in RCS could have resulted from competition by higher 26 and saturating concentrations of receptor-binding but non-inhibitory antibodies in 27 these convalescent subjects and with the assay used. The present study has several limitations. First, our study sample consisted of a ASCs in the two groups were compared using a two-tailed Wilcoxon-Mann-Whitney 29 test. *, p < 0.05. 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