ViroidsViroids

Lyndsay MurrowBMS 265

NomenclatureNomenclature

Viroid = “virus- like”

Adapted from Flores R et al (1998) Arch Virol 143, 623-629.

1974: Confirmation that viroids are non-coding

1973: Electron micrograph shows viroid’s hairpin structure

DiscoveryDiscoveryEarly 1960s: Raymer and O’Brien develop a bioassay for the agent causing potato spindle tuber disease

1965: Raymer teams up with Diener; they show that agent is not a typical virion

1971: Diener demonstrates that the agent is a free non-coding RNA, coins the term viroid

1968: Characterization of chrysanthemum stunt and citrus exocortis as non-typical viruses

1978: PSTVd is sequenced

1976: EM shows that viroids form closed circular RNAs

Example MembersExample MembersGenus Pospiviroids:PSTVd (potato spindle tuber)

Genus Hostuviroids:HSVd (hop stunt)

Genus Cocadviroids:CCCVd (coconut cadang-cadang)

Genus Apscaviroids:ASSVd (apple scar skin)

Genus Coleviroids:CbVd 1 (coleus blumei 1)

Genus Avsunviroids:ASBVd (avocado sunblotch)

Genus Pelamoviroids:PLMVd (peach latent mosaic)

Pospiviroidae: Nuclear, CCR, no hammerhead self-cleavage

Avsunviroidae: Chloroplastic, no CCR, hammerhead self-cleavage

Evolution and ConservationEvolution and Conservation

Diener TO (1996) Virus Genes 11, 119-131.William G. Scott

BiogenesisBiogenesis

Adapted from Daròs J et al (2006) EMBO Reports 7, 593-598.

Cellular Functions (Pathogenicity)Cellular Functions (Pathogenicity)

Pray LA (2004) The Scientist 18, 23.

Mechanism of ActionMechanism of Action

Martick M and Scott WG (2006) SSRL Research Highlight 11, 119-131. http://ssrl.slac.stanford.edu/research/highlights_archive/ribozyme.html http://rnaworld.bio.ku.edu

Potential as a ToolPotential as a Tool

Citti L and Rainaldi G (2005) Curr Gene Ther 5, 11-24.