Figure 2(A) NLRP3+/+ and NLRP3-/- THP-1 cells were incubated with SARS-CoV-2 at an MOI of 1 for 1 h, followed by washing away extracellular viruses and further culture for 3 h. Otherwise, cells were stimulated with 10 μM nigericin for 30 min following pretreatment with 1 μg/ml LPS for 3 h. Cell pellets were collected and immunoblotted with antibodies against the indicated proteins. Treatment with 1 μg/ml LPS for 3 h served as a control. (B, C) THP-1 cells stably expressing the indicated SARS-CoV-2 genes were stimulated with 10 μM nigericin for 30 min following pretreatment with 1 μg/ml LPS for 3 h. Supernatants were collected for an ELISA assay to determine supernatant IL-1β levels (B) and cell pellets were subjected to a cell viability assay to verify the percentage of viable cells through checking cellular ATP levels (C). For B-C, Student's t-test was used and data were shown as means±SD of three technical replicates. NS, non-significant. Data information: control vector used here was empty vector corresponded to the nucleocapsid-containing vector. Student's t-test was used and data were shown as means±SD of three technical replicates. **, P<0.01; NS, non-significant. Similar results were observed for at least three times. (D-F) THP-1 cells stably expressing the nucleocapsid gene or control vector were stimulated with 10 μM nigericin for 30 min following pretreatment with 1 μg/ml LPS for 3 h. Supernatants and cell pellets were collected and immunoblotted with antibodies against the indicated proteins (D). The percentage of viable cells was determined through checking cellular ATP levels in cell pellets (E). The percentage of cells undergoing pyroptosis was calculated through checking released LDH in the supernatants (F). For E, F, Student's t-test was used and data were shown as means±SD of three technical replicates. **, P<0.01; NS, non-significant. Data information: control vector used here was empty vector corresponded to the nucleocapsid-containing vector. Student's t-test was used and data were shown as means±SD of three technical replicates. **, P<0.01; NS, non-significant. Similar results were observed for at least three times. Human CD14+ monocytes were electroporated with plasmids encoding the nucleocapsid or control vector for 36 h, followed by stimulation with 10 μM nigericin for 30 min post pretreatment with 1 μg/ml LPS for 3 h. Supernatants and cell pellets were collected and immunoblotted with antibodies against the indicated proteins (G). Human CD14+ monocytes were electroporated with plasmids encoding the nucleocapsid or control vector for 36 h, followed by stimulation with 10 μM nigericin for 30 min post pretreatment with 1 μg/ml LPS for 3 h. Supernatants and cell pellets were collected and The percentage of viable cells was determined through checking cellular ATP levels in cell pellets (H). The percentage of cells undergoing pyroptosis was calculated through checking released LDH in the supernatants (I). Student's t-test was used and data were shown as means±SD of three technical replicates. **, P<0.01; NS, non-significant. Data information: control vector used here was empty vector corresponded to the nucleocapsid-containing vector. Student's t-test was used and data were shown as means±SD of three technical replicates. **, P<0.01; NS, non-significant. Similar results were observed for at least three times.