Proposed mechanism of N-NS4B/WARF4 synthesis. In the center the WNV 3′ genomic organization is shown. WARF4 is dashed, the first and the last base of the alternative reading frame are pointed by stars. On the top, the synthesis of NS4B by canonical translation mechanism in 0 frame and maturation is shown. Below is displayed the proposed mechanism of N-NS4B/WARF4 synthesis through translation in −1 frame. The amino acids sequences of the two proteins are showed, the different COOH terminals of the two proteins are underlined.