Fig 1: Analysis of human primary cells, infected with the VOC 202012/01 lineage B.1.1.7 variant in the absence or presence of D3, by immunofluorescence assays and RT-PCR. (a) The cells untreated or infected with the VOC 202012/01 variant of SARS-CoV-2, in the absence or presence of D3 for 72 h at 37 °C, were fixed, washed and permeabilised, as described in the Methods. After blocking, the slides were incubated with the relevant primary antibodies overnight at 4 °C: anti-ACE2 (1:100; ab15348; Abcam) or anti-SARS-CoV-2 Nucleoprotein (N) Antibody (1:100; No. 35-579, ProSci), followed by the relevant secondary anti-mouse Alexa Fluor 488 (1:200; ab150113; Abcam) and anti-Rabbit Alexa Fluor 546 (1:200; A-11035; ThermoFisher), respectively. DNA was stained with DAPI (1:5000; #62254; Thermo Fisher). Microscopy images were obtained with the Elyra 7 platform (Zeiss) with the optical Lattice SIM technology, using the 63 × oil immersion objective. (b) Quantification of the mean fluorescence intensity was performed by using the ZEN software (Zeiss, black edition). (c) Cell extracts were analyzed by RT-PCR for measuring the expression of N1 viral gene and the levels of the indicated cytokines. In parallel, the extract of uninfected cells was used as negative control.