Serum IgG responses to MPER, MPER carrier and gp41 9 weeks after primary immunization. Mice were immunized with L(MPLA + HerHap-PEG-MPER carrier) (A, C, E) or L(MPLA + MPER carrier) (B, D), at weeks 0, 3 and 6. Each curve represents an individual mouse (5 mice/liposome formulation). Monoclonal antibodies 4E10 and WR339 (5 ng/well) were used as positive controls for the assay for gp41 antibodies (F). Values represent the mean ± standard deviation of triplicate determinations.