Construction of West Nile virus and dengue virus chimeras for use in a live virus vaccine to prevent disease caused by West Nile virus

A nucleic acid chimera comprising a first nucleotide sequence encoding two structural proteins from a West Nile virus, wherein the structural proteins are premembrane/membrane (prM) and envelope (E), and a second nucleotide sequence encoding capsid (C) and nonstructural proteins from a dengue virus and comprising:

• a cleavage site for joining the dengue virus capsid protein and the West Nile virus prM protein, wherein the West Nile virus prM protein contains aspartic acid (Asp) at a position 3 amino acids downstream of the cleavage site and contains threonine (Thr) at a position 6 amino acids downstream of the cleavage site, wherein the cleavage site corresponds to amino acid position 3 of SEQ ID NO:
• 3;
• and
• a mutation encoding a threonine at a nucleotide corresponding to nucleotide position 4891 and/or a mutation encoding a proline at a nucleotide corresponding to nucleotide position 4995 of SEQ ID NO:
• 38.