Figure 1.
A. DV virions are enveloped, containing three structural proteins; the envelope (E) and membrane (M) proteins (dark and light blue, respectively) are anchored to the viral membrane (green), and the capsid protein (C) (orange) covers the viral genome (red) (kindly provided by Dr. Richard J. Kuhn). B. The dengue genome is a single-stranded, positive-polarity RNA with a unique open reading frame flanked by 5′ and 3′ untranslated regions (UTR). It encodes for three structural and seven nonstructural proteins, represented by colored, stylized boxes. The name of DV viral proteins is indicated. C. Diagram of chimeric DV vaccine approach. Chimeric flaviviruses are constructed by swapping the prM and E coding sequences from an attenuated backbone for those of a heterologous DV strain. Viral RNA is obtained in vitro and transfected. Vero cells are used to amplify the infectivity of the chimeric virus, which is formed by the respective DV serotype envelope proteins with the replication machinery (represented by gears) of an attenuated, related flavivirus.