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An effective immune response against viral infections depends on the activation of cytotoxic T cells that can clear infection by killing virus-infected cells. Proper activation of these T cells depends on professional antigen-presenting cells, such as dendritic cells (DCs). In this review, we will discuss the potential of peptide-based vaccines for prevention and treatment of viral diseases. We will describe features of an effective response against both acute and chronic infections, such as an appropriate magnitude, breadth, and quality and discuss requirements for inducing such an effective antiviral immune response. We will address modifications that affect presentation of vaccine components by DCs, including choice of antigen, adjuvants, and formulation. Furthermore, we will describe differences in design between preventive and therapeutic peptide-based vaccines. The ultimate goal in the design of preventive vaccines is to develop a universal vaccine that cross-protects against multiple strains of the virus. For therapeutic vaccines, cross-protection is of less importance, but enhancing existing T cell responses is essential. Although peptide vaccination is successful in inducing responses in human papillomavirus (HPV) infected patients, there are still several challenges such as choosing the right target epitopes, choosing safe adjuvants that improve immunogenicity of these epitopes, and steering the immune response in the desired direction. We will conclude with an overview of the current status of peptide vaccination, hurdles to overcome, and prospects for the future.

The hydrophobin SC3 belongs to a class of small proteins functioning in the growth and development of fungi. Its unique amphipathic property and remarkable surface activity make it interesting not only for biological studies but also for medical and industrial applications. Biophysical studies have revealed that SC3 possesses at least three distinct conformations, named "soluble-state SC3" for the protein in solution, and "␣-helical-state SC3" and "␤-sheet-state SC3" for the different states of the protein associated at a hydrophobic-water interface. The present fluorescence study shows that the microenvironment of the dansyl-labeled N terminus of soluble-state SC3 is relatively hydrophobic, whereas it is hydrophilic for ␣-helical-state and ␤-sheet-state SC3. Fluorescence collisional quenching indicates that the N terminus of soluble-state SC3 is more solvent-accessible than those of ␣-helical-state and ␤-sheet-state SC3, with Stern-Volmer constants for acrylamide of 4.63, 0.02, and 0.2 M −1 for the different states, respectively. Fluorescence resonance energy transfer measurements show that soluble-state SC3 tends to associate in solution but dissociates in TFA. Fluorescence energy transfer was eliminated by conversion of soluble-state SC3 to ␣-helical-state SC3 on a hydrophobic surface, indicating a spatial separation of the molecules in this state. By inducing the ␤-sheet state, structural changes were observed, both by CD and by fluorescence, that could be fit to two exponentials with lifetimes of about 10 min and 4 h. Molecules in the ␤-sheet state also underwent a slow change in spatial proximity on the hydrophobic surface, as revealed by the reappearance of fluorescence resonance energy transfer in time.Keywords: Hydrophobin; circular dichroism spectroscopy; fluorescence collisional quenching; fluorescence resonance energy transfer Hydrophobins are a class of small proteins that play an important role in fungal growth and development, for example, the formation of aerial hyphae and the attachment of hyphae to hydrophobic surfaces (Wösten et al. , 1994avan Wetter et al. 1996van Wetter et al. , 2000. These proteins are remarkable in that they self-assemble into an amphipathic membrane at hydrophobic-hydrophilic interfaces. This makes them interesting not only from a biological point of view, but also for medical and industrial applications (Wessels 1997;Scholtmeijer et al. 2001). Two different types of hydrophobins, class I and class II, have been distinguished based on the differences in their hydropathy patterns and biophysical properties (Wessels 1994).SC3, secreted by Schizophyllum commune, is the best characterized class I hydrophobin. It contains eight cysteine Reprint requests to: G.T. Robillard, BioMaDe Technology Foundation, Nijenborgh 4, 9747 AG Groningen, The Netherlands; e-mail: Robillard@ biomade.nl; fax: 031-50-3634321.Abbreviations: CD, circular dichroism spectroscopy; ATR-FTIR, attenuated total reflection-Fourier transform infrared spectroscopy; TFA, trifluoroacetic acid; FRET, fluor...

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