Development of a Novel ELISA to Detect anti-DENV NS1 IgG in sera from DENV Preimmune Mice Models

Abstract

Dengue is a single-stranded positive-sense RNA virus and has become one of the most critical public health concerns in tropical and subtropical regions. Severe dengue cases can result in dysfunction in the endothelium integrity and increased vascular permeability, leading to severe shock syndrome. The efforts to develop a safe and effective vaccine to prevent dengue virus (DENV) have faced many challenges, particularly in creating one to offer protection against all four antigenically different serotypes. The non-structural glycoprotein 1 (NS1) of the dengue viral genome is found to be mainly associated with intracellular membranes and organelles in infected cells and is highly conserved. It has been proven helpful for diagnosing acute dengue infections and is a likely target for developing a vaccine candidate. DENV research and development is restricted by the need for more available animal models that can fully mimic the pathogenesis of human disease. Mice and other rodents have shown resistance to DENV infection and do not sustain signs of the disease. One approach to utilizing mice models to study the pathology of DENV is to use immunocompetent mice with deficiencies in their host defense response. AG129 mice, direct descendants of the 129S6/SvEv mouse, have null alpha, beta, and gamma receptor interferon (Type II) and are vulnerable to DENV infection. Since NS1 is detectable in the sera of DENV-infected mice as early as one-day post-onset of symptoms, we developed a novel ELISA to measure NS1 IgG antibodies in 129S6, and AG129 immunized mice models. This thesis aimed to investigate the immunogenicity of a tetravalent vaccine candidate against DENV. In order to ensure serotype specificity and broad coverage, mice were vaccinated with a tetravalent test article under different stress conditions. Notably, both mice models exhibit significant responses, with observations suggesting a potential for a specific NS1 capture assay. Our findings suggest that the 129S6 mice model did not exhibit sensitivity to the type of immunogens, as intact interferon interferes with any live virus in the test articles. Alternatively, in the AG129 mice model, two stressed test articles (pH and freeze-thawed) provided different NS1 responses. These data will help build the foundation of a particular NS1 capture assays for all four DENV serotypes. However, despite promising outcomes, further optimization and validation of the ELISA is necessary to quantify antibody response and immunogenicity assessment.