Investigation of zika virus (ZIKV) antigens to develop serological tests and vaccine approaches

Abstract

The recent Zika virus (ZIKV) epidemic created a sense of urgency to develop a vaccine to prevent and control ZIKV infection, especially because of the complications observed in pregnant women and newborn. The administration of a vaccine in pregnant or fertile age women increases the needed of safe vaccine strategies. Thus, the main goal of this project is to work on different vaccine approaches, using inactivated viral particles as well as subunits of ZIKV proteins. Both strategies demand the addition of adjuvants in order to induce the production of neutralizing antibodies able to block the infection of host cells.Importantly, different aspects related to the vaccine production and monitoring have been extensively performed by researchers in laboratories at University of Sao Paulo (USP) and Butantan Institute (IB), where the conditions of ZIKV culture and modifications that are important for a final product that will be adequate to be used in humans have been performed. The conditions of virus inactivation and concentration were stablished by the researchers; and the immunogenicity and the induction of protection have been experimentally tested.Therefore, the PD researcher will work directly on these experiments as well as testing structural and non-structural ZIKV proteins and their fragments, particularly the domain III of protein E and the C-terminal NS1 fragment. In addition, the vaccine strategies will include the use of several adjuvants and vehicle of administration (Non-toxic derivatives of LT and ETEC, MPLA, flagellin of Salmonella, spores of B. Subtilis, liposomes, and VLPs), parenteral administration (intramuscular and subcutaneous), and mucosal administration (sublingual and nasal). Notably, the different vaccine formulations will be monitored both in vitro and in vivo assays frequently used in USP laboratories. In vitro assays include the use of different cell lines and sera samples of patients to perform plaque assays, qPCR and flow cytometry technologies, that will be frequently used to increase the results robustness. On the other hand in vivo assays consist of using interferon ±/² receptor knockout mice susceptible to ZIKV infection (AG129 e AB6) as a model to study vaccine immune protection. Assays as Plaque Reduction Neutralization Test (PRNT) and Antibody-dependent enhancement (ADE) will be used to monitor the antibody`s virus neutralization capacity. Additionally, humoral and cellular responses produced by vaccinated mice will be investigated by the presence of specific antibodies and T cells (CD4+ and CD8+) in different tissues including the mucosa. These experiments will enable the determination of the vaccine efficacy as well as the cross-reactivity of anti-DENV e anti-ZIKV on virus neutralization or amplification. The proposed techniques in this project were established by our research group and they are all described in previously published scientific articles. Importantly, this study will contribute to define new vaccine strategies and applicable experimental models for ZIKV studies.