Structural biology and drug development against the protein NS5 Zika virus

Abstract

Zika virus is a member of the Flavivirus family, with a genome consisting of a single positive strand of RNA encoding for three structural and seven non-structural proteins. Its occurrence in Brazil was first reported in April 2015 and since then 148.905 cases have been reported. Typical symptoms are mild fever, rash, arthralgia, headache and conjunctivitis, similar though less intense, to the symptoms of dengue. The biggest impact of the epidemic stems from the occurrence of a large number of cases of microcephaly in infants and fetuses of pregnant women who were infected with the virus. Given these facts many studies are being carried out to search for a possible drug candidate against ZIKV, since it is has been spreading not only in Brazil but also in many countries of South and Central America. Structure-Based Drug Design (SBDD) is one of the preferred methodologies available for the discovery of new drug candidates. Based on the three dimensional structure of validated target proteins, this method uses various computational techniques, always integrated with the experimental procedures of synthesis and evaluation of the designed compounds, and have been increasingly used to develop new drugs. The nonstructural protein NS5 ZIKV contains two domains that play central functions for viral RNA replication in the infected cell: a RNA-dependent RNA Polymerase domain (RdPd) and a methyltransferase domain. The specific blocking of any of these functions is lethal to virus replication. This project proposes the expression, purification and structure determination by X-ray crystallography of the NS5 ZIKV protein (integral and functional domains) as well as the search for ligands of this protein, possible drug candidates using natural products or synthetic substances developed in the Center for Research and Innovation in Biodiversity and Drug Discovery (CIBFar-CEPID). Once hits (molecules with promising activity) are identified, these will be optimized by cycles of design-chemical synthesis-biochemical/biological evaluation, focusing both criteria of affinity and specificity for the target, as well as the pharmacokinetics and toxicology adequate to pharmacological applications. The ultimate goal is to develop at least ONE anti-zika drug candidate, able to enter into preclinical and clinical studies. (AU)