T cell epitope mapping of the e-protein of West Nile virus in BALB/c mice.

West Nile virus (WNV) is a zoonotic virus, which is transmitted by mosquitoes. It is the causative agent of the disease syndrome called West Nile fever. In some human cases, a WNV infection can be associated with severe neurological symptoms. The immune response to WNV is multifactorial and includes both humoral and cellular immunity. T-cell epitope mapping of the WNV envelope (E) protein has been performed in C57BL/6 mice, but not in BALB/c mice. Therefore, we performed in BALB/c mice a T-cell epitope mapping using a series of peptides spanning the WNV envelope (E) protein. To this end, the WNV-E specific T cell repertoire was first expanded by vaccinating BALB/c mice with a DNA vaccine that generates subviral particles that resemble West Nile virus. Furthermore, the WNV structural protein was expressed in Escherichia coli as a series of overlapping 20-mer peptides fused to a carrier-protein. Cytokine-based ELISPOT assays using these purified peptides revealed positive WNV-specific T cell responses to peptides within the different domains of the E-protein.