( F) Full–length spike (S–FL) protein–transfected HEK293T cells exhibited more DNA damage than empty vector-, S1–, and S2–transfected cells under different DNA damage conditions. The values represent the mean ± SD from three independent experiments (see representative FACS plots in Figure S4A,B). ( D, E) Only full-length spike protein inhibits non-homologous end joining (NHEJ) and homologous recombination (HR) DNA repair. ( B, C) Effect of titrated expression of the spike protein on DNA repair in HEK–293T cells. The S2 subunit consists of the fusion peptide (FP, 788–806 residues), heptapeptide repeat sequence 1 (HR1, 912–984 residues), HR2 (1163–1213 residues), TM domain (TM, 1213–1237 residues), and cytoplasm domain (CT,1237–1273 residues). The S1 subunit includes an N–terminal domain (NTD, 14–305 residues) and a receptor–binding domain (RBD, 319–541 residues). ( A) Schematic of the primary structure of the SARS–CoV–2 spike protein. Severe acute respiratory syndrome coronavirus 2 (SARS–CoV–2) spike protein inhibits DNA damage repair. Statistical significance was determined using one-way analysis of variance (ANOVA) in ( C, E). The values represent the mean ± SD, n = 3. The values represent the mean ± SD from three independent experiments (see representative FACS plots in Figure S2B). ( E) Effect of E.V and SARS–CoV–2 proteins on HR DNA repair. ( D) Schematic of the DR-GFP reporter used to monitor homologous recombination (HR). The values represent the mean ± standard deviation (SD) from three independent experiments (see representative FACS plots in Figure S2A). ( C) Effect of empty vector (E.V) and SARS–CoV–2 proteins on NHEJ DNA repair. ( B) Schematic of the EJ5-GFP reporter used to monitor non-homologous end joining (NHEJ). Immunofluorescence was performed at 24 h after transfection of the plasmid expressing the viral proteins into HEK293T cells. ( A) Subcellular distribution of the SARS–CoV–2 proteins. Our findings reveal a potential molecular mechanism by which the spike protein might impede adaptive immunity and underscore the potential side effects of full-length spike-based vaccines.ĭNA damage repair SARS–CoV–2 V(D)J recombination spike vaccine.Įffect of severe acute respiratory syndrome coronavirus 2 (SARS–CoV–2) nuclear-localized proteins on DNA damage repair. Mechanistically, we found that the spike protein localizes in the nucleus and inhibits DNA damage repair by impeding key DNA repair protein BRCA1 and 53BP1 recruitment to the damage site. Here, by using an in vitro cell line, we report that the SARS-CoV-2 spike protein significantly inhibits DNA damage repair, which is required for effective V(D)J recombination in adaptive immunity. Clinical studies have indicated that patients with severe COVID-19 exhibit delayed and weak adaptive immune responses however, the mechanism by which SARS-CoV-2 impedes adaptive immunity remains unclear. Adaptive immunity plays a crucial role in fighting against SARS-CoV-2 infection and directly influences the clinical outcomes of patients. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led to the coronavirus disease 2019 (COVID-19) pandemic, severely affecting public health and the global economy.
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