Background
Dengue fever is an important mosquito-borne viral disease, caused by one of the four closely related but antigenically distinct dengue virus serotypes (DENV-1 to 4). According to World Health Organization (WHO), the annual incidence of dengue infection is 100 million, of which approximately 500,000 patients develop dengue hemorrhagic fever (DHF) that may lead to dengue shock syndrome (DSS) with a mortality rate of more than 2.5 % [1–3]. DENV has a positive sense RNA genome (genus Flavivirus; family Flaviviridae) of approximately 11 Kb in size. Infection with one serotype does not provide immunity against other serotypes, so a person living in an endemic area could have up to four DENV infections during his/her life span [4, 5]. All four serotypes of dengue are able to produce DHF or DSS in humans after infection is established [6]. In the tropical and subtropical climates of the world, the incidence of dengue is continuously on the rise due to suitable climatic conditions for dengue vector growth [7]. Furthermore, antibodies raised against the membrane protein prM are known not to neutralize the virus but they can cause the antibody-dependent enhancement (ADE) [8–10]. Due to ADE, and in order to protect individuals from DENV infections, it becomes critical to survey the dengue serotypes in any particular area.