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Therefore, an effective vaccine against dengue virus must induce a simultaneous and strong immune response against all four serotypes.
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The leading hypothesis to explain pathogenesis of dengue virus is the antibody-dependent enhancement of infection which suggests cross reactive sub-neutralizing antibodies may enhance the severity of infection. Individuals with secondary dengue infection produce cross-reactive and non-neutralizing antibodies and also memory T cells, which can enhance virus replication and over production of cytokines, that in turn are risk factors for DHF.
![editseq editseq](https://d3i71xaburhd42.cloudfront.net/556532d1629aaed021e87d8fc604ba679373791c/32-Table2.13-1.png)
One of the challenges of dengue infection is that, although antibodies produced against the infecting serotype confer lifelong immunity against the infecting serotype, re-infection by another serotype has been associated with sever disease. There is still no approved vaccine or drug for this virus. Dengue fever, dengue hemorrhagic fever (DHF), and dengue shock syndrome are important viral diseases caused by any of the four serotypes. It is estimated that more than 2.5 billion people are at the risk of infection by dengue virus. The dengue virus group comprises an independent serogroup of four closely related but antigenically distinct serotypes 1, 2, 3, and 4. They are transmitted via mosquito Aedes aegypti. Dengue viruses are belonging to genus Flavivirus of the family Flaviviridae.