Fig. 5.

Effect of varying peptide PN19 time of administration and adsorption with SARS-CoV-2 cell mixtures and substrate cells on SARS-CoV-2 replication. A- SARS-CoV-2 infection of Vero E6 cells at MOI of 0.01 in presence of peptide PN19 at 0.1, 1, 10 and 100 μM concentration added at 1 h before infection (T-1), at the time of infection (T0) and 1 h (T1) and 2 h (T2) after infection. SARS-CoV-2 infection exposed to the indicated doses of PN19 was assayed with the viral plaque reduction assay. B- In the adsorption treatment Peptide PN19 (1 mM solution) was incubated at 4°C for 1 h with the indicated material: SARS-CoV-2 adsorbed to Vero E6 cells (5 × 10⁵) (Cell-SARS-CoV-2) or Vero E6 cells (5 × 10⁵) (Cell-mock) alone for 1 h at 4°C or at 37°C. Then, peptide solution after adsorption treatment was centrifuged at 600 X g for 15 min (to remove cells) followed by 20,000 X g for 90 min (to remove residual virions), and then assayed at the concentration indicted for inhibition of the same SARS-CoV-2 used in PN19 adsorption treatment, by the standard procedure. The peptide PN19 solution after such treatment inoculated alone in the Vero E6 cells exhibited absence of virus infectivity. Values shown are means ± standard deviations (SD) of the inhibitory values obtained in 3 independent experiments. Asterisks indicate significative difference at * p<0.05, ** p<0.01, *** p<0.001 (Student's t-test).