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. 2017 Jul 27;91(16):e00438-17. doi: 10.1128/JVI.00438-17

TABLE 1.

Cell permeabilization

Cell type EC50a (μM)
EBOV peptides
RESTV peptides
MelP5b
E40ox E40red E23ox E23red E17ox E15ox E14ox R42ox R42red R25ox R25red
MDCK 5.5 I 11 I 14 16 I ND ND ND ND 2.8
MDCKc 25 I 72 I ND ND ND ND ND ND ND 9.0
HeLa 19 I 16 I 15 21 I ND ND ND ND 3.1
Vero 20 I 22 I 52 37 I I I 56 I 3.6
Verod 18 ND 11 ND ND ND ND 100 ND 49 ND 1.0
CHO 5.4 I 17 I 15 21 I I I 68 I 1.6
RBCe >200 ND >200 ND >200 >200 I I ND >200 ND 3.6
a

EC50, concentration required for 50% lytic or toxic effect. Oxidized EBOV or RESTV peptides (ox) have a disulfide cross-link between the conserved cysteines, while reduced peptides (red) do not. Except where noted, all measurements are based on Sytox green entry into cells after 1 h of incubation of serially diluted peptide with a cell monolayer in the presence of 100 nM Sytox green. Sytox green entry, which does not occur in unperturbed cells, is measured by the dramatically increased fluorescence of the probe when it binds to nuclear DNA (Fig. 3). I, less than 5% permeabilization was observed at the highest concentration studied, 200 μM for hemolysis and 50 or 100 μM for Sytox green entry; >200, more than 5% hemolysis was observed at the highest concentration, but the EC50 is greater than 200 μM peptide; ND, the experiment was not done. All values are the means of the results of ≥3 experiments. The standard deviations had an average value of 30% of the EC50s listed.

b

MelP5 is a lytic control peptide derived from the bee venom toxin, melittin (23).

c

Loss of transepithelial electrical resistance in a confluent monolayer of MDCK cells.

d

Cytotoxicity of peptides after 24 h of incubation with VERO cells, measured using alamarBlue fluorescence.

e

Hemolysis of human erythrocytes, measured by assessing the peptide-induced release of hemoglobin.