Virus Characteristics: Chikungunya virus (CHIKV) is an enveloped, single-stranded, positive-sense RNA virus classified within the genus Alphavirus of the family Togaviridae. Virions are spherical, approximately 60-70 nm in diameter, and possess a lipid envelope with icosahedral symmetry. The genome is ~11.6-11.8 kb in length, capped at the 5' end with a 7-methylguanosine cap and polyadenylated at the 3' end. It encodes four non-structural proteins (nsP1, nsP2, nsP3, nsP4) and five structural proteins (capsid and envelope glycoproteins E1, E2, E3, and 6K). The nucleocapsid core-formed by 240 copies of the capsid protein-encloses the genomic RNA, while the outer envelope displays 80 trimeric spikes composed of E1/E2 heterodimers. The E2 glycoprotein mediates binding to host-cell receptors, whereas the E1 glycoprotein drives membrane fusion. CHIKV is primarily transmitted by Aedes aegypti and Aedes albopictus mosquitoes. It is sensitive to heat, desiccation, and common disinfectants and exists in multiple genotypes; among them, the ECSA genotype's E1-A226V mutation enhances adaptability to A. albopictus.

Genome Structure, Protein Expression, and Virus Assembly of Chikungunya Virus