Virus-Like Particle Secretion and Genotype-Dependent Immunogenicity of Dengue Virus Serotype 2 DNA Vaccine

Abstract

Dengue virus (DENV), composed of four distinct serotypes, is the most important and rapidly emerging arthropod-borne pathogen and imposes substantial economic and public health burdens. We constructed candidate vaccines containing the DNA of five of the genotypes of dengue virus serotype 2 (DENV-2) and evaluated the immunogenicity, the neutralizing (Nt) activity of the elicited antibodies, and the protective efficacy elicited in mice immunized with the vaccine candidates. We observed a significant correlation between the level of in vitro virus-like particle secretion, the elicited antibody response, and the protective efficacy of the vaccines containing the DNA of the different DENV genotypes in immunized mice. However, higher total IgG antibody levels did not always translate into higher Nt antibodies against homologous and heterologous viruses. We also found that, in contrast to previous reports, more than 50% of total IgG targeted ectodomain III (EDIII) of the E protein, and a substantial fraction of this population was interdomain highly neutralizing flavivirus subgroup-cross-reactive antibodies, such as monoclonal antibody 1B7-5. In addition, the lack of a critical epitope ( Dengue virus (DENV) is the most important and rapidly emerging arthropod-borne pathogen and imposes substantial economic and public health burdens, especially in tropical and subtropical countries (1, 2). It is transmitted to humans through the bite of Aedes mosquitoes. A recent study estimated that 390 million DENV infections occur annually worldwide, with 500,000 of these cases being severe and with 25,000 cases resulting in death, mostly among children (3). Despite the impact of this disease, neither a licensed vaccine nor a specific antiviral drug is available; vector control is the only control measure available (4, 5). There are four antigenically distinct serotypes of the virus (DENV serotype 1 [DENV-1] to DENV-4), and each can cause a wide spectrum of clinical manifestations, including asymptomatic infection, self-limited flu-like dengue fever (DF), and the severe life-threatening dengue hemorrhagic fever and dengue shock syndrome (DHF/DSS) (2, 6).

Secretion of dengue virus envelope protein ectodomain from mammalian cells is dependent on domain II serotype and affects the immune response upon DNA vaccination

“…Although there are a number of studies describing DNA vaccines against dengue Azevedo et al, 2011;Galula et al, 2014;Khanam et al, 2006;Konishi et al, 2006;Ocazionez Jimenez & Lopes da Fonseca, 2000;Prompetchara et al, 2014;Ramanathan et al, 2009;Raviprakash et al, 2001Raviprakash et al, , 2006, to date there has been only one human clinical trial for a dengue DNA vaccine involving a Phase 1 study of a plasmid expressing the PrM and E proteins of DENV1 . In all cases, these vaccines have been proved to be safe and well-tolerated in humans, although low immunogenicity is still a concern associated with genetic vaccines in general (Coban et al, 2011;Danko et al, 2011).…”

Scanning Mutagenesis Studies Reveal a Potential Intramolecular Interaction within the C-Terminal Half of Dengue Virus NS2A Involved in Viral RNA Replication and Virus Assembly and Secretion

“…An antigen-capture enzyme-linked immunosorbent assay (ELISA) was performed to detect and quantify the level of secretion of virus particles harvested from HEK-293 cells transfected with WT or NS2A mutant plasmids (39). Briefly, flat-bottom 96-well MaxiSorp Nunc-Immuno plates (Nunc, Roskilde, Denmark) were coated with 50 l of rabbit anti-DENV2 VLP serum at 1:500 in carbonate buffer (0.015 M Na 2 CO 3 , 0.035 M NaHCO 3 , pH 9.6) and incubated overnight at 4°C, and the wells were blocked with 200 l of 1% bovine serum albumin in PBS for 1 h at 37°C.…”

Thioguanine-based DENV-2 NS2B/NS3 protease inhibitors: Virtual screening, synthesis, biological evaluation and molecular modelling

“…DENV carries a positive single strand RNA in its genome and five serotypes (DENV-1 to 5) have been identified. DENV-2 is the most prevalent type in dengue epidemic, especially in the South East Asian region and has been associated with severe dengue cases [9]. The new serotype (DENV-5) [10] was discovered in 2013 in Sarawak, Malaysia further complicates the prevention and treatment of the disease.…”