Dengue virus protein and antibody. Molecular model of a dengue virus 2 envelope protein (red) complexed with antibody Mab 4E11 (blue). The function of the protein is to bind to the surface of its target cell and allow the viral genes into the cell, where replication occurs. Antibodies bind to the envelope proteins to prevent this. The dengue virus (DENV), transmitted by mosquito bites, causes the tropical disease dengue fever in humans. Symptoms can range from a mild fever and joint pain to spontaneous skin bleeding and death due to circulatory failure.