The dengue virus is a tiny structure that can only replicate inside a host organism. The four closely related dengue viruses — DEN-1, DEN-2, DEN-3, and DEN-4 — are found in the same regions of the world. The dengue virus is a roughly spherical structure composed of the viral genome and capsid proteins surrounded by an envelope and a shell of proteins. After infecting a host cell, the dengue virus hijacks the host cell's machinery to replicate the viral RNA genome and viral proteins. After maturing, the newly synthesized dengue viruses are released and go on to infect other host cells.