Chikungunya virus E protein ectodomain（CHIKV-E）

Chikungunya virus (CHIKV) belongs to the Semliki Forest antigenic group of the genus Alphaviridae, which includes other arthritogenic alphaviruses, such as o’nyong-nyong, Ross River, Barmah Forest, and Mayaro viruses.Its genome is closely related to that of o’nyong-nyong virus, and consists of a single 11.8-kbp strand of positive sense RNA, which encodes a 2472 amino acid nonstructural and a 1244 amino acid structural polyprotein.3 The polyproteins give rise to the four nonstructural proteins (nsP1-4) that make up the viral replication machine, and five structural proteins. Each spherical viral particle is approximately 70 nm in diameter and is comprised of a strand of genomic RNA, encapsidated by capsid (C) proteins, surrounded by a host cell–derived lipid bilayer spiked with heterodimers of envelope proteins E1 and E2.4 The other two structural proteins, 6K and E3, are leader peptides for E1 and E2, respectively, and are not observed in abundance in the mature virion.