Table 1.

Functions of the various structural and non-structural Proteins of CHIKV

Protein	Size(aa)	Function
Non-structural Proteins	2474	P1234 precursor protein
nsP1	535	Methyltransferase and guanylyl transferase activities capping and methylation of new viral RNAs; is the only membrane anchor for the replication complex
nsP2	798	C-terminal cysteine (auto)protease activity cleaves initial polyprotein into individual non-structural proteins thus enabling viral replication; has also N-terminal helicase, nucleoside triphosphatase and RNA triphosphatase activities; interferes with the host cells mRNA transcription & translation and inhibits interferon signalling
nsP3	530	Interacts with several host proteins, possibly modulates protein poly- and mono-ADP-ribosylation; influences host cells stress response; Phosphoprotein, important for RNA minus-strand synthesis
nsP4	611	RNA-dependent RNA polymerase (RdRp) essential for viral replication; presumed terminal transferase activity
Structural Proteins	1244	Structural precursor protein
C (Capsid)	261	Forms nucleocapsid core by encapsidating genomic RNA; carboxyl domain is an autocatalytic serine protease
P62/PE2	487	Precursor/Intermediate, later cleaved into E2 and E3 by host furin protease
E1	435	Surface protein; Type II fusion protein; mediates fusion of viral envelope and cellular membrane by fusion peptides
E2	423	Surface protein; major target of neutralizing antibodies; mediates binding to receptors and attachment factors on host cell membrane
E3	64	N-terminal domain is uncleaved leader peptide of E2, suspected to shield fusion peptide in E1 during egress
6 K	61	Leader peptide of E1; presumed ion channel; may enhance particle assembly and release
TF	76	Transframe protein, produced via ribosomal frameshifting, presumed ion channel, may enhance particle release, shares N-terminus with 6 K

Aa amino acid number; C capsid; nsP non-structural protein; RdRp RNA-dependent RNA polymerase; TF transframe protein