V-specific temporal antibody responses in mice immunized with different vaccination regimens: codon optimized V DNA vaccine alone (V-DNA), V DNA vaccine prime followed by V protein boost formulated with IFA (V-DNA+Prot/IFA), V protein formulated with IFA (V-Prot/IFA), V protein alone (V-Prot), or empty DNA vaccine vector alone (Vector). V-specific antibody responses were measured by ELISA at different time points using pooled mouse sera from each group against V protein. Each curve represents mean OD values with standard error of duplicated assays for each mouse group, at 1:500 serum dilution.