Plant Viruses Online   

Descriptions and Lists from the VIDE Database

Hop trefoil 2 betacryptovirus

Index

• Nomenclature
• Host range, transmission and symptoms
• Physical and biochemical properties
• Taxonomy and relationships
• Comments and References

Data collated by E. Luisoni, 1991.

Nomenclature

Acronym

HTCV-2

ICTV decimal code

49.0.4.0.003

Host range and symptoms

Natural host range and symptoms

• Medicago lupulina - symptomless.

Transmission

Transmitted by means not involving a vector. Virus not transmitted by mechanical inoculation; not transmitted by grafting; not transmitted by contact between plants; transmitted by seed.

Geographical distribution

Found, but with no evidence of spread, in in Italy, in plants grown from seeds from Denmark and Poland, probably widespread elsewhere.

Experimental host range

Few (<3) families susceptible.

Maintenance and propagation hosts

Medicago lupulina.

Susceptible host species

• Medicago lupulina

Families containing susceptible hosts

• Leguminosae-Papilionoideae (1/1)

Sources of host-range data

Boccardo et al. (1987); Luisoni et al. (1987).

Physical and biochemical properties

Properties of particles in sap

Leaf sap contains few virions (very few). Electron microscopy: use ISEM. To aid negative stain adhesion of purified preparations, it is best to use carbon-coated Formvar-film that has been treated with glow-discharge in air at 0.1 torr.

Purification method

Luisoni et al. (1987).

Particle morphology

Virions isometric; not enveloped; 38 nm in diameter; rounded in profile; with a conspicuous capsomere arrangement.

Biochemical properties

Genome consists of RNA; double-stranded; linear. Total genome size 5.15 kb (pairs). Genome of three parts (in the mixture hop trefoil cryptic viruses 2 and 3); largest (or only) genome part the largest 2.05 kb (pairs); the 2nd largest 1.65 kb (pairs); the 3rd largest 1.45 kb (pairs). Genomic nucleic acid isolated by Boccardo et al. (1985); Luisoni et al. (1987).

Taxonomy and relationships

Betacryptovirus: Partitiviridae

Virus(es) with serologically related virions

Red clover 2 and white clover 2 betacryptoviruses.

Additional comments on relationships

No serological relation to alphacryptoviruses.

Best tests for diagnosis

ISEM and decoration may distinguish between hop trefoil 2 betacryptovirus and hop trefoil 1 and 3 alphacryptoviruses. ELISA may be useful but it does not distinguish between 1, 2 and 3. The detection by PAGE of dsRNAs similar to those found for the mixture hop trefoil cryptic viruses 2 and 3 can confirm serology.

Comments and References

References

• Boccardo, G., Milne, R.G., Luisoni, E., Lisa, V. and Accotto, G.P. (1985). Virology 147: 29.
• Boccardo, G., Lisa, V., Luisoni, E. and Milne, R.G. (1987). Adv. Virus Res. 32: 171.
• Luisoni, E., Milne, R.G., Accotto, G.P. and Boccardo, G. (1987). Intervirology 28: 144.

Cite this publication as: Brunt, A.A., Crabtree, K., Dallwitz, M.J., Gibbs, A.J., Watson, L. and Zurcher, E.J. (eds.) (1996 onwards). `Plant Viruses Online: Descriptions and Lists from the VIDE Database. Version: 20^th August 1996.' URL http://biology.anu.edu.au/Groups/MES/vide/

Dallwitz (1980) and Dallwitz, Paine and Zurcher (1993) should also be cited.