Dengue fever (DF) is a mosquito-borne viral disease widely distributed in most tropical and subtropical regions. An estimated 50â100 million human cases occur annually. One of the important features of this disease is the presence of its severe form, dengue hemorrhagic fever (DHF). Approximately 250,000â500,000 cases of DHF have been reported every year. The causative agent of DF and DHF is any of four types of dengue virus (dengue type 1â4 virus; designated DENV1â4), members of the genus Flavivirus in the family Flaviviridae. There are currently no approved vaccines and no specific antiviral drugs available against the dengue virus. Epidemiological evidence indicates that once an individual becomes infected with one type of dengue virus they are usually protected from subsequent homotypic infection, but disease severity can progress from DF to DHF mostly following heterotypic infection. One of the potential mechanisms that leads tothis increased disease severity is the presence of non-neutralizing cross-reactive antibodies and/or cross-reactive memory T lymphocytes induced by an earlier infection. Therefore, a tetravalent vaccine that can induce immune responses against all four types of dengue virus would be required for developing a safe and effective dengue vaccine. It is highly probable that neutralizing antibodies constitute an immunological correlate of protection for dengue, although this is still being debated.
Last date updated on June, 2014