Structural Differences Observed in Arboviruses of the Alphavirus and Flavivirus Genera

Figure 4

The 5′ terminus of the genome is capped and the polyprotein is expressed as a single polypeptide. The 3′ terminus is not polyadenylated but rather forms a loop structure. The locations of the nsP and structural proteins are switched with respect to the 5′ end of the RNA compared with the alphaviruses. It has been proposed that this switch occurred via recombination in an ancient precursor, thus retaining the structural glycoprotein folds. Capsid protein, preM, and E proteins are proteolytically processed as indicated by the enzymes shown by the arrows and arrowheads Virus DB: VBRC genome browser.