CROI 2024 Abstract eBook

Abstract eBook

Poster Abstracts

Conclusion: This work provides the biological basis for the development of host-directed therapies based on the NLR pathway to boost the innate immune system for an early viral clearance and infection resolution. SARS-CoV-2 Natural Infection Elicits Cross-Reactive Immunity to OC43 Micaela Garziano , Claudia Vanetti, Sergio Strizzi, Irma Saulle, Maria Luisa Murno, Fiona Limanaqi, Valentina Artusa, Mario Clerici, Daria Trabattoni, Mara biasin University of Milan, Milan, Italy Background: The 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 by both natural infection and/or vaccination is able to confer protection against a new OC43 re-infection. Methods: Neutralization assay of plasma and saliva samples from 49 uninfected SARS-CoV-2-vaccinated subjects (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). Results: Neutralizing activity (NA) against SARS-CoV-2 significantly increased after third dose administration in plasma (p<0.0001) but not in saliva from SV; however, it doesn't seem to protect against OC43. On the other hand, SARS-CoV 2 NA triggered by natural infection was able to defend against OC43 infection in both plasma (p<0.05) and saliva (p<0.01) samples. Conclusion: Our data suggest that compared to vaccine administration, SARS-CoV-2 natural infection is able to elicit a broader and cross-reactive immunity, which results in protection from OC43 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 SARS-CoV-2-Specific T-Cells Correlate With Airway Virus Control During Early Acute Infection Freya U Hourani 1 , Tabea M. Eser 1 , Alison Tarke 2 , Leo Swadling 3 , Flora Deak 1 , Kathrin Held 1 , Mohammed I. Ahmed 1 , Laura Olbrich 1 , Andreas Wieser 1 , Inge Kroidl 1 , Alessandro Sette 2 , Mala Maini 3 , Michael Hoelscher 1 , Christof Geldmacher 1 1 Klinikum der Universität München, Munich, Germany, 2 La Jolla Institute for Allergy and Immunology, La Jolla, CA, USA, 3 University College London, London, United Kingdom Background: SARS-CoV-2-specific T cell responses, including those targeting the Nucleocapsid (N) and the conserved Replication-Transcription Complex (RTC), have been associated with protection from infection and airway virus control. Methods: We studied the specificity and magnitude of SARS-CoV-2 T cell responses within the first week of symptom onset in previously unexposed individuals before seroconversion, using an IFN- ƴ ELISPOT assay and peptides pools spanning the SARS-CoV-2 virion structural proteins N, membrane (M) and spike (S), as well as the nonstructural proteins NSP3, ORF3a, and the RTC (consisting of NSP7, NSP8, NSP12 and NSP13). Moreover, pools of MHC Class I- and II-restricted peptides (CD8RE and CD4RE, respectively) spanning the entire SARS-CoV-2 proteome (excluding the S region), as well as a custom pool of 197 non-overlapping 8- to 14mer peptides, selected for their predicted binding affinity to the five most common MHC Class I HLA-A and B alle groups in Europe, were also investigated. To investigate cross-reactivity of the acute SARS-CoV-2 T cell response with the common cold coronavirus HCoV-HKU1, the dominant strain during late 2019/early 2020, an HCoV-HKU1 whole-proteome peptide pool was tested. Results: Within the first week of symptom onset, N-specific T cells had the highest median response magnitude (105 Spot Forming Colonies/106 PBMC), followed by S (52.5 SFC/106 PBMC), NSP3, M, ORF3a and RTC (32.5 - 37.5 SFC/106 PBMC) and NSP13 (22.5 SFC/106 PBMC). The megapools CD4RE, CD8RE, and custom MHC Class I pool exhibited a median response of 205, 150 and 117.5 SFC/106 PBMC, respectively, indicating a comparable magnitude of CD4 vs. CD8 T cell responses. Upper airway viral load inversely correlated with N-, S-, RTC-, NSP13-, ORF3a and CD4RE-specific T cell response magnitudes (p<0.05,

following inflammatory stimuli ERAPs can be secreted and modulate both the acquired and natural immune response. We investigated in an in vitro model whether exogenous recombinant human (rh) ERAP can play a role in modulating SARS-CoV-2 infection/replication by boosting the antiviral potential of immunocompetent cells. Methods: Granulocytes isolated from 10 healthy controls were stimulated with 300ng/mL of rhERAP1, rhERAP2 or rhERAP1+rhERAP2. After 24h, these cells were co-cultured with in vitro SARS-CoV-2 infected A549-ACE2 cell line and the following parameters were assessed: 1) viral replication; 2) neutrophil activation; 3) cytokine secretion;4) Phagocytosis and cell migration. In parallel, ERAP1 and ERAP2 mRNA concentration were quantified in unstimulated and Spike-stimulated PBMCs as well as in plasma of 10 mild (MD) and 10 severe (SD) COVID-19 patients. Results: Granulocytes incubation with rhERAPs significantly reduced SARS CoV-2 replication in A549-ACE2 infected cells (rhERAP1 p<0.05; rhERAP2 p<0.05; COMBO p<0.01). This antiviral activity was associated with: neutrophil activation and degranulation (CD15+CD16+CD66b++MPO) (p<0.05); increased neutrophil migration (p<0.001) and reduction of SARS-CoV-2 neutrophils internalization (p<0.05), and the release of several cytokines/ chemokines, mainly IL-8 (p<0.01). Ex vivo analyses showed that ERAP mRNA expression was drastically reduced in both unstimulated (p<0.05) and Spike stimulated (p<0.05) PBMCs of SD compared to MD. Conversely, a higher ERAP concentration was detected in plasma of SD compared MD (p<0.05). Conclusion: ERAPs trigger several antiviral mechanisms in neutrophils suggesting that their anti-SARS-CoV-2 potential is not limited to their canonical role in Ag presentation and CD8+ T cell activation. These findings pose the premise to further investigate potential use of ERAP in novel preventive and therapeutic approaches against viral infections. Innate Immune Response Through NOD1 Agonists Prevents SARS-CoV-2 Infection in Lung Epithelial Cells Edurne Garcia-Vidal 1 , Ignasi Calba 2 , Eva Riveira-Muñoz 1 , Elisabet García 1 , Bonaventura Clotet 1 , Pere Serra-Mitjà 3 , Cecilia Cabrera 2 , Ester Ballana 1 , Roger Badia 2 1 IrsiCaixa Institute for AIDS Research, Badalona, Spain, 2 Institute for Health Science Research Germans Trias i Pujol, Badalona, Spain, 3 Hospital Sant Pau, Barcelona, Spain Background: The difficulty to exert a direct antiviral activity in the lung, is one of the major roadblocks for the management of respiratory infections, such as Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV- 2). Boosting the innate immune response of the respiratory mucosa at early stages of the infection is a potential alternative intervention for the treatment of respiratory infections. Methods: Ability to induce innate immune response was evaluated by flow cytometry, measuring IL8 production upon 24h incubation with distinct immunomodulators targeting the main pattern recognition receptors (PPRs), in lung epithelial A549 or myeloid THP-1 cells. NOD-like receptor (NLR) agonists were characterized through their proinflammatory profile in A549 and the activation of the NF-κB and the Interferon- sensitive response element (ISRE) pathways in A549-DualTM hACE2-TMPRSS2 cells (A549-Dual). Specificity of TriDAP (NOD1) and M-TriDAP (NOD1/2) agonists in lung epithelial cells was assessed by transient downregulation of NOD1 gene expression (siRNA) and selective NOD1 and NOD1/2 inhibitors. Systemic activation by NOD agonists was evaluated in PBMCs. Antiviral activity of NOD agonists was determined in A549-Dual cells in vitro challenged with SARS-CoV-2-GFP as measured by the percentage GFP+ by flow cytometry at 48 h infection. Results: Amongst the immunomodulators tested, NLR agonists TriDAP (NOD1) and M-TriDAP (dual NOD1/2) showed the best potency and selectivity, inducing up to 3.3-fold increase of IL8+ cells in a dose- dependent manner, without impairing cell viability. Response to NOD1 and dual NOD1/2 agonists was 2-fold- higher compared to LPS control. NOD1 and dual NOD1/2 agonist activity involved NF-κB and ISRE pathways induction. NOD1 downregulation (siRNA) resulted in a 93% reduction of IL-8+ cells cocultured with TriDAP or M-TriDAP. Selective NOD1 and NOD1/2 inhibitors impaired the NOD1-induced activation of NF-κB and ISRE pathways. PBMCs were unresponsive to NOD1 agonists, suggesting tissue specific activity of NOD1 in lung epithelial cells, without a global systemic activation. Finally, NOD1 agonist Tri-DAP and dual NOD1/2 agonist M-TriDAP, promoted an antiviral environment that prevented SARS-CoV 2 replication in lung epithelial cells (57% protection).

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CROI 2024