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Envelope Protein Structure of Zika Virus - A Target For Vaccine Development And Therapeutics

Sidra Shafique

Zika Virus epidemic is expanding from Brazil to Americas. ZV is of immense public health concern, as it’s infection is resulting in physical as well as mental health issues in the people, especially among the pregnant women of the affected area. ZV infection causes neurological complications in adults and Congenital Zika Syndrome in infected fetuses. Unlike other viruses of this family, ZV escapes the host immune system, survives at higher temperatures and crosses the anatomical barriers of human body. Still there are structural similarities between ZV and Dengue Virus (DV) that are the mainstay of the research regarding its structure and viral-host immune system interactions.. Zika virus (ZV), a member of Flavivirus Family, has a positive sense RNA genome, a capsid and an outer shell. The envelope (E) protein is the major component of the shell that is the first interface interacting with host immune system, internal environment and the cell membranes infecting the host cells. Outermost shell of ZV is icosahedral in protein configuration with 180 E proteins in total, arranged in finger-like dimers. Three dimers line parallel to each other creating a diamond shaped asymmetric structure which can be further subdivided into symmetric triangles having half of the dimers triplicates. E protein is anchored by M protein in viral lipid membrane via a stem and a loop structure. A lipid membrane lines underneath the outer shell which covers the innermost chamber, the capsid. Capsid contains the genome, responsible for translation of three structural and seven nonstructural proteins. The potential targets for vaccine and drug development are in the Fusion Loop of Domain II in E protein monomers and NS1, NS2B, NS3, NS5, the nonstructural proteins. The identified targets are aimed to halt the replication and infectivity of the ZV at different stages of its maturity. Understanding of ZV structure is the key to identify the effective targets for prospective advancements in the vaccine and therapeutics development.