Figure 3.
Expression of P. vivax region II, P. knowlesi β region II, and chimeric domain CH4 as secreted proteins in COS cells. COS cells transfected with constructs designed to express P. vivax region II (A), P. knowlesi β region II (B), and chimera CH4 (C) as secreted proteins were metabolically labeled with [35S]Met/[35S]Cys. Recombinant domains were detected in culture supernatants (Sup) by immunoprecipitation (IMPT) with monoclonal antibody DL6 (Mab DL6) directed against HSV gD sequences in the fusion proteins. Supernatants were used either directly for immunoprecipitation (−) or after preabsorption with Duffy-positive human erythrocytes (D+), Duffy-negative human erythrocytes (D−), or rhesus erythrocytes (Rh). Radio-labeled culture supernatants were also used directly in erythrocyte-binding assays (EBA) with D+, D−, and Rh erythrocytes.