Fig. 6.

Effect of substituting and adding amino acids at the N-terminus of S-pep7. (A) Amino acid substitutions or additions introduced at the N-terminus of S-pep7. The N-terminal Glu¹²²² in S-pep7 was replaced by a single Val (S-pep7A), two Val (S-pep7B), a single Arg (S-pep7C), or two Arg (S-pep7D). All altered amino acids are italicized and underlined. (B) In vitro processive DNA synthesis conducted by recombinant proteins of HSV-1 UL42 and UL30 in the presence of increasing concentrations of each modified S-peptide. (C) HSV-1 plaque reduction assay. Following 1 h absorption of HSV-1 onto Vero cells, S-pep7A and S-pep7B were added at increasing concentrations and plaques counted after 55 h (left and middle). For direct comparison, inhibition of HSV-1 plaques by Acyclovir (ACV) was also performed (right). (D) Cytotoxicity of S-pep7B. Vero cells were treated with S-pep7B at two-fold serial dilutions for 24h and measured for intracellular ATP content and LDH leakage. Data represents mean ±SD obtained from at least two independent experiments performed in triplicate. (E) Specificity of S-pep7B as shown by its inability to block both in vitro processive DNA synthesis conducted by vaccinia virus proteins (Left) and vaccinia virus infection (Right). The data represents mean ±SD from at least two independent experiments performed in duplicate.