Table 1.

General properties of togaviruses

Virus aspectDescription of property
VirionSpherical particle measuring 50–70 nm in diameter
Virion envelope composed of host-derived lipid bilayer embedded with spikes made up of the E2, E1, and sometimes E3 glycoproteins
Icosahedral core comprising the viral genome, which is encapsidated with multiple copies of the capsid proteins
GenomeSingle-stranded, positive-polarity RNA
3 × 106 to 4 × 106 Da in size
Methyl7guanosine capped at the 5′ terminus and polyadenylated at the 3′ terminus
Two ORFs; the 5′-proximal ORF encodes ns proteins, and the 3′ ORF encodes structural proteins
ReplicationThe genomic RNA, subgenomic RNA, RI representing partial dsRNA, and RF representing fully dsRNA are produced in RV-infected cells
Virus-modified endosomes/lysosomes termed replication complexes are sites of RV replication
The genomic and subgenomic RNA serves as the mRNA for the synthesis of ns and structural proteins, respectively