P-112 SARS-CoV-2 natural infection, but not vaccine-induced immunity, elicits cross-reactive immunity to OC43

• Published in: Sexually transmitted infections Vol. 100; no. Suppl 1; p. A218
• Main Authors: Garziano, M, Vanetti, C, Strizzi, S, Saulle, I, Limanaqi, F, Artusa, V, Cano Fiestas, M, Ogno, P, Clerici, M, Trabattoni, D, Biasin, M
• Format: Journal Article
• Language: English
• Published: London BMJ Publishing Group Ltd 01.06.2024; BMJ Publishing Group LTD
• Subjects: Infections; Plasma; Severe acute respiratory syndrome coronavirus 2; Vaccines
• ISSN: 1368-4973; 1472-3263
• DOI: 10.1136/sextrans-ICAR-2024.201

BackgroundThe recent SARS-CoV-2 pandemic renewed interest in other previously discovered non-severe acute respiratory syndrome human coronaviruses. Among these, OC43 is a seasonal human coronaviruses widely diffused in the global population (90% seroprevalence in adults), mostly responsible for mild respiratory symptoms. As OC43 protective immunity is short lasting, the aim of this study was to verify if systemic and mucosal SARS-CoV-2 humoral immunity elicited either by natural infection and/or vaccination confers protection against a new OC43 re-infection.MethodsNeutralization assayes using plasma and saliva samples of 49 SARS-CoV-2-vaccinated subjects who were never naturally infected and received three doses of BNT162b2 RNA vaccine (SV) and 25 SARS-CoV-2-infected and vaccinated subjects (SIV) were performed against ’wild type’ SARS-CoV-2 lineage B.1 (EU) and OC43 in VeroE6 cell lines. Sampling was carried out immediately before (T0) and 15 days (T1) post third-dose administration (SV) or 15 days post-infection (SIV). SARS-CoV-2 anti-RDB NAbs were measured employing a commercial ELISA kit (Viazyme, Delft, Netherlands). Analyses were performed on the saliva of a subset of SV (n = 18) and SIV (n = 15) subjects at T1ResultsSARS-CoV-2-specific neutralizing activity (NA) significantly increased after third vaccine dose administration in plasma (p<0.0001) and saliva (p<0.01) from SV; however, this NA was not protective against OC43. Conversely, SARS-CoV-2 NA triggered by natural infection in plasma and saliva of SIV proved to be cross-reactive and protective against OC43 in both plasma (p<0.05) and saliva samples (p<0.05). A statistically significant difference was observed in the assay of anti-RBD NAbs in saliva samples at T1 (p<0.001). Indeed, the SIV group showed higher levels than the SV group.ConclusionsOverall, this study on immunity to SARS-CoV-2 suggests that compared to vaccine-induced immunity natural infection elicits a broader and cross-reactive immunity, which results in protection from viruses sharing sequence homology, at both systemic and mucosal level. As the oral cavity represents the main entry route for coronaviruses, these results support the development of a pan-coronavirus vaccine to prevent new infections and re-infections.