Fig 1.
Schematic of validation procedure of UV inactivation protocol for SARS-CoV-2.
Samples were generated with 3 biological replicates under the conditions that lead to no detectable virus. Fresh cells were treated with the UV irradiated samples, and these treated cells were passaged for three weeks to test for viral replication. The inactivation protocol is the same for HSV-1 and HCMV, except for differences in the number of cells and passaging times, which are described in the Materials and Methods section.
Fig 2.
Mixing cells during irradiation increases inactivation efficiency.
Vero B4 cells were infected with HSV-1 and irradiated in tissue vials. Cells were treated with the indicated irradiation dose in a single interval (No Mixing, black line) or were treated repeatedly with a fluence of 2,500 mJ/cm2 followed by mixing for the total dose stated (With Mixing, green line). Sample inactivation was evaluated by plaque assay with a limit of detection (LoD) of 5x102 PFU/mL. Each dose curve was performed with n = 1.
Fig 3.
Inactivation of HSV-1 infected cells.
Vero B4 cells infected with HSV-1 were UV-inactivated. (A) The virus titres of samples taken during inactivation validation were determined with a limit of detection (LoD) of 5 PFU/mL. The before inactivation and UV inactivated samples were performed with biological replicates, n = 3, and the standard deviation is shown. The untreated control sample was performed with n = 1. (B) Immunofluorescence imaging of cells treated with the UV-inactivated infected cells was performed with biological replicates, n = 3. Cells were stained for the HSV-1 protein ICP0 and with DAPI. The scale bar represents 100 μm.
Fig 4.
Inactivation of HCMV infected cells.
HFF-1 cells infected with HCMV were UV-inactivated. (A) The virus titres of samples taken during inactivation validation were determined with a limit of detection (LoD) of 5 PFU/mL. The before inactivation and UV inactivated samples were performed with biological replicates, n = 3, and the standard deviation is shown. The untreated control sample was performed with n = 1. (B) Immunofluorescence imaging of cells treated with the UV-inactivated infected cells was performed with biological replicates, n = 3. Cells were stained for the HCMV proteins IE1/2 and with DAPI. The scale bar represents 100 μm.
Fig 5.
Inactivation of SARS-CoV-2 infected cells.
Vero E6 cells infected with SARS-CoV-2 were UV-inactivated. (A) The virus titres of samples taken during inactivation validation were determined with a limit of detection (LoD) of 5 PFU/mL. The before inactivation and UV inactivated samples were performed with biological replicates, n = 3, and the standard deviation is shown. The untreated control sample was performed with n = 1. (B) Immunofluorescence imaging of cells treated with the UV-inactivated infected cells was performed with biological replicates, n = 3. Cells were stained for the SARS-CoV-2 protein N and with DAPI. The scale bar represents 100 μm.