Generation and purification of monoclonal antibodies. BALB/c mice were primed and boosted at 3-week intervals with insect cell-generated, purified, recombinant WNV E protein (25 µg) that was complexed with adjuvant (RIBI Immunochemical). Approximately 1 month after the last boost, we harvested serum and tested it for immunoreactivity against solid-phase purified E. Mice with high titers (>1/10,000) were boosted intravenously with purified E protein (5 µg) in PBS. We harvested splenocytes 3 d later and fused them to P3X63Ag8.653 myeloma cells to generate hybridomas according to published procedures 40 . We purified monoclonal antibodies against WNV or other control antigens by stan-dard protein A or protein G chromatography according to the manufacturer's instructions (Pharmacia).