The mosquito-transmitted Dengue virus (DV) is the causative agent of dengue fever (DF), the most prevalent arthropod-borne viral illness in humans with 50-100 million afflicted individuals.
DF is characterized by high fever, chills, body aches and skin rash and ranges from mild, flu-like symptoms to severe forms, the so called dengue hemorrhagic fever (DHF), and the dengue shock syndrome (DSS). About 250,000 individuals per year manifest these severe forms, which have a mortality rate of about 10 percent. DV infection has been described in more than 100 countries, with 2.5 billion people living in dengue endemic areas. Given the dramatic geographic expansion of epidemic DF and DHF, the World Health Organization has classified this disease as a major international public health concern.
Geographic Pattern of DENGUE Prevalence
Four serologically distinct serotypes that are distinguishable by neutralization and complement fixation tests have been described. Infections with one serotype confers a long-lasting immunity to re-infection with the same DV serotype but on the other hand increases the risk of severe dengue manifestation upon infection with a heterologous serotype.
It is assumed that antibody-mediated enhancement substantially contributes to an accelerated virus spread, replication and viremia. Other mechanisms that are under debate are reactivation of an inadequate T-cell immune response during secondary infection, viral factors of pathogenesis and host genetics.
Current therapy is symptomatic and primarily based on fluid replacement. Neither selective therapy nor an approved vaccine are available. The problem in DV vaccine development is to achieve a rapid and robust protection against all 4 serotypes at the same time.