Figure 2

Effect of peptides on plaque formation. (a) Photos show plaque formation at 10 × 10 magnification (infected by 100 pfu of MDV without peptides, i.e., 100% plaque formation) and 0% plaque formation (infected by 100 pfu MDV with 50 μM gHH2 in cell-pre treatment assay, i.e., 100% plaque formation inhibition). (b) The plaque formation using immunofluorescent (IFA) staining with 1:100 diluted antibody anti-pp24, and plaque formation inhibition are shown from left to right, respectively. (c) Five peptides (gHH1, gHH2, gHH3, gHH5, and gBH1) with IC₅₀ values below 12 μM were selected for further study. In addition, NHR2 (i.e. NDV HR2) and gHH6 were selected as control proteins in the paper. Note: The IC₅₀ are the means ± standard deviations determined from three independent experiments. (d) CEF cells were exposed to peptides at concentration of 25 μM either prior to infection (cell pre-treatment, cell pre-), during entry (co-treatment, co-) or after virus penetration (post-treatment, post-), or alternatively, the virus was pre-incubated with peptides for 1 h at 37°C before addition to the cells (virus pre-treatment, virus pre-). Experiments were performed in triplicate, and the plaque formation percentages were calculated. Peptides gHH1, gHH2, gHH3, gHH5, gBH1, NHR2, gHH6, and NHR1 (i.e. NDV HR1) are shown from left to right, respectively.