Dengue virus surface protein molecule. Computer model showing the molecular structure of the envelope glycoprotein found on the surface of the dengue haemorrhagic fever (DHF) virus. The function of this protein is to bind to the surface of its target cell and allow the viral genes into the cell, where replication occurs. The type of protein displayed by a virus determines its host. Symptoms of dengue fever can range from a mild fever and joint pain to spontaneous bleeding of the skin and circulatory failure, which are often fatal.