FIG. 6.

Neutralization of BPV1 infection by αL2 36-49 antibody can be competed with a peptide corresponding to residues 36 to 49. (A and B) Pseudovirus-encapsidated DNA of 8fwb encodes the GFP cDNA, and infections were analyzed by FACS. C127 cells were infected with pseudovirions alone (gray bar) (same data in A and B) in the presence of affinity-purified αL2 36-49 antibody (white bar) (same data in A and B) or (A) antibody that was preincubated with BPV1 L2 peptide at residues 36 to 49 in increasing concentrations of 10 nM, 100 nM, and 1 μM (black bars). An increase in infection signifies a loss of neutralization in the presence of the added peptide. (B) Antibody was preincubated with scrambled BPV1 L2 peptide at residues 36 to 49 in increasing concentrations of 10 nM, 100 nM, and 1 μM (black bars). No increase in infection was observed; thus, scrambled peptide does not interfere with the neutralization by αL2 36-49. Data bars represent the averages of three experiments, and standard deviations are demonstrated by error bars. (C) Focus-forming assay of C127 cells infected with genuine BPV1 virions. Bar 1, number of foci formed from the addition of virions alone; bar 2, foci formed with the addition of αL2 36-49; bar 3, foci formed with antibody and scrambled BPV1 L2 peptide at residues 36 to 49 (no loss of neutralization was observed); bar 4, foci formed with antibody and 10 μM wild-type BPV1 L2 peptide at residues 36 to 49. A complete loss of neutralization was observed. C127 cell foci were visible after staining with methylene blue. Data represent average numbers of foci formed in three plates under the same conditions. Standard deviations are shown by error bars.