Total Ig and IgG isotype responses to the HIV-v polypeptide components. Responses were measured by ELISA in sera from HIV-v or NRP-v immunised HLA-A*0201 transgenic mice. Total Ig responses to the Vpr (A), Vif (B), Rev (C) and Nef (D) peptides are represented as average ng/ml (± SEM) versus sera dilution. IgG2c (E) and IgG1 (F) responses to Vif and Nef peptides were quantified in a 1:200 serum dilution. A positive response, indicated by an asterisk (*) was defined as an increment of at least 100% over the background response with a statistical significance of p < 0.05.