Association of antigens to ISCOMATRIX adjuvant using metal chelation leads to improved CTL responses

The association of antigen with ISCOMATRIX trade mark adjuvant has been shown to be important for the optimal induction of cytotoxic T lymphocyte (CTL) responses. Here, we describe a simple broadly applicable method for associating recombinant proteins with hexa-histidine tags to ISCOMATRIX trade mark adjuvant utilising metal-affinity chelating interactions. The metal chelation binding step can be performed in a wide range of buffers, including commonly used denaturants such as urea, which makes it an ideal strategy for formulating proteins which are otherwise insoluble. Following association of protein with the chelating ISCOMATRIX trade mark adjuvant, the denaturant can be removed. Further, we show enhanced CTL responses with a protein-associated chelating ISCOMATRIX trade mark vaccine compared to a non-associated ISCOMATRIX trade mark vaccine.