Notes on Genus: Trichovirus
Type member: Apple chlorotic leaf spot virus
The genus Trichovirus
(named from the Greek thrix
=hair) is one of the genera in the family Betaflexiviridae
. It contains viruses originally included tentatively in the genus Closterovirus
, but which have shorter virions, a very different genome organisation and a poly(A) tail.
Virions filamentous and flexuous, not enveloped, 640-800 nm long and 12 nm in diameter. Nucleocapsids are cross-banded, obliquely striated, and with rope-like features (depending on the negative staining method).
Virions composed of 5% nucleic acid.
Monopartite, linear, single stranded, positive sense RNA, 6300-7600 nucleotides long. The 3' terminus has a poly(A) tract. The 5' terminus probably has a methylated nucleotide cap.
Genus Genomic Organization
The genome is translated by means of 3 slightly overlapping ORFs. The largest ORF (ORF1) is probably involved in replication, while ORF2 (putative movement protein) and ORF3 (coat protein) are expressed from subgenomic mRNAs.
Type Member Genomic Organization
The genome is believed to be translated by means of three open reading frames:
- 216.5 kDa polyprotein: putative replicase
- 50.4 kDa Movement protein
- 21.4 kDa Coat protein