Heterologous expression of FMDV immunodominant epitopes and HSP70 in P. pastoris and the subsequent immune response in mice.

Mycobacterium tuberculosis heat shock protein70 (HSP70) is a major antigen with both chaperone and cytokine functions. It has been used as an adjuvant to induce or potentiate humoral and cellular immunity, both in the form of a mixture with peptide antigens, and as a fusion protein. We have evaluated the effects of HSP70 on foot and mouth virus (FMDV) subunit vaccines. FMDV VP1, and a synthetic multi-epitope FMDV (EG), and VP1-HSP70 and EG-HSP70 fusion proteins were all heterologously expressed in the yeast Pichia pastoris, and used as antigen in mice. The recombinant VP1 and EG alone was able to induce both humoral and marginal cell-mediated immune responses, while the HSP70 fusions markedly enhanced both the humoral and cell-mediated immune responses. The most prominent immune responses arose from vaccination with the EG-HSP70 fusion product. Both fusion protein-induced Th1-like cytokine (IFN-gamma) and Th2-like cytokine (IL-4) were identified.