CTV has filamentous virions 2000 × 10–12 nm in
size, composed of one molecule of single stranded
RNA of positive polarity and two capsid proteins
(CP) of 25 kDa (p25) and 27 kDa (p27) that coat 95%
and 5% of the particle length, respectively, conferring
to the virions a rattlesnake structure (Agranovsky et
al. 1995; Febres et al. 1996). The CTV genomic RNA
has 19.2 kb (Karasev et al. 1995) and is organized in
12 open reading frames (ORFs) and untranslated regions
(UTRs) at the 5’ and 3’ termini. ORF1a encodes
a 349 kDa polyprotein containing two papain-like
protease, methyltransferase and helicase-like domains.
Translation of the polyprotein is thought to
occasionally continue through the polymerase-like
domain (ORF1b) by a +1 frameshift mechanism
(Karasev et al. 1995).