{"doi":"10.1002/ctm2.576","title":"SARS‐CoV‐2 infection in lung transplant recipients induces circulating exosomes with SARS‐CoV‐2 spike protein S2","abstract":"This is a single center study to demonstrate the importance of exosomes in developing a more sensitive method to detect severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection from symptomatic lung transplant recipients (LTxRs) along with symptomatic and asymptomatic patients waiting for lung transplant (LTx). These exosomes carrying SARS-CoV-2 spike protein can be immunogenic to mice. World Health Organization declared SARS-CoV-2 a global pandemic in March 2020.1 This virus caused coronavirus disease 2019 (COVID-19), which has killed over 4.8 people worldwide to date. Diagnosis of COVID-19 is commonly established by detecting the SARS-CoV-2 within respiratory secretions using polymerase chain reaction (PCR) assays.2, 3 For the patients with end-stage respiratory disease, LTx is the last treatment option.3 In our previous reports, we have shown exosomes containing viral antigens in LTxRs with respiratory viral infections and this may play a role in the pathogenesis of chronic lung allograft dysfunction.4 We demonstrate that exosomes carry SARS-CoV-2 spike protein S2 in symptomatic and asymptomatic LTxR individuals waiting for LTx, suggesting that detection of exosomes with SARS-CoV-2 spike protein S2 can be developed as more sensitive approach for detecting SARS-CoV-2 infection. We analyzed exosomes from plasma of 27 LTxRs-COVID-19 and 57 asymptomatic patients (Table S1) (Asx) for the presence of exosomes carrying the SARS-CoV-2 spike and nucleocapsid protein (December 2019 to March 2021). The results demonstrated the presence of SARS-CoV-2 spike antigen S2 and nucleocapsid on exosomes from all symptomatic LTxRs (Figure 1A, Table S2A). In addition, 6/6 patients positive for SARS-CoV-2 infection by RT-PCR (Figure 2B, Table S2) and 16/57 (28.0%) asymptomatic patients waiting for LTx (Asx) also had exosomes positive for the SARS-CoV-2 spike protein S2 and nucleocapsid protein (Figure 2C, Table S2A). The specificity toward SARS-CoV-2 was confirmed by Western blot analysis using specific antibodies (Abs) (Figure 3A, B). Exosomes containing SARS-CoV-2 spike protein S2 from 7 patients from symptomatic and asymptomatic groups were also tested for other proteins. These exosomes demonstrated the presence of other peptides including angiotensin II receptor type 1 (AGTR1), which has suggestive role in viral entry into the cells in addition to proinflammatory responses,5 macrophage stimulating 1 (MST1), MST1/2 is a mediator of the innate immune response, eliciting macrophage phagocytosis and cytokines,6 Granzyme-B (GRA-B), which plays an important role in immune regulation and cytotoxicity of cells in response to viral infections.7 In addition, there is also presence of lung self-antigens (SAgs) (Kα1 Tubulin [Kα1T], Collagen V [Col-V]) and nuclear factor kappa B (NFkB) (Figure 2A, B and Table S2B). AGTR1, GRA-B and MST1 were elevated in plasma exosomes from LTxRs-COVID-19 and in Asx (p < .05). Presence of these peptides indicates an active or recent SARS-CoV-2 infection. Exosomes containing SARS-CoV-2 spike protein S2 was further confirmed by mass spectroscopy and transmission electron microscopy (TEM). Desired protein bands were extracted from SDS–PAGE of positive exosomes and subjected to mass spectroscopy. Bands from two samples were aligned with peptides of SARS-CoV-2 spike protein and nucleoprotein: (a) LPDDFTGCVIAWNSNNLDSKVGGNYNYLYRLFRK with UNIPORT ID PODTC2 and molecular weight 141.1 kDa and (b) WYFYYLGTGPEAGLPYGANK with UNIPORT ID PODTC9 and molecular weight 45.6 kDa. TEM and immunostaining of the exosomes using Abs specific to SARS-CoV-2 spike protein S2 and nucleocapsid protein revealed the presence of the spike protein S2 and nucleocapsid antigen on the surface of exosomes (Figure 3A). Mass Spectroscopy and TEM results are in agreement to the Western blot results. Cytokine analysis of plasma from LTxRs-COVID-19 and Asx, demonstrated increased levels of proinflammatory cytokines (IL12, RANTES, IP10, IFNγ, Eotaxin,","journal":"Clinical and Translational Medicine","year":2021,"id":181603,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":16,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9561,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2021-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":410890,"name":"Sofya Tokman","orcid":"0000-0003-2821-8776","position":1,"is_corresponding":false},{"id":628058,"name":"Timothy P. Fleming","orcid":"0000-0002-8661-1210","position":2,"is_corresponding":false},{"id":733248,"name":"Gabriel N. Maine","orcid":null,"position":3,"is_corresponding":false},{"id":733249,"name":"Kristina Sanborn","orcid":null,"position":4,"is_corresponding":false},{"id":288869,"name":"Ramsey R. Hachem","orcid":"0000-0002-0708-1937","position":5,"is_corresponding":false},{"id":232806,"name":"Ankit Bharat","orcid":"0000-0002-1248-0457","position":6,"is_corresponding":false},{"id":288872,"name":"Michael A. Smith","orcid":"0000-0002-2191-5475","position":7,"is_corresponding":false},{"id":288873,"name":"Ross M. Bremner","orcid":"0000-0003-2216-9109","position":8,"is_corresponding":false},{"id":288874,"name":"Thalachallour Mohanakumar","orcid":"0000-0001-9873-4018","position":9,"is_corresponding":false},{"id":288865,"name":"Sandhya Bansal","orcid":"0000-0003-0630-9175","position":0,"is_corresponding":true}],"reference_count":9,"raw_metadata":null,"created_at":"2026-07-18T23:48:05.146883Z","pmid":"34841719","pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}