title: Characterisation of a virus infecting the wall-free prokaryote Spiroplasma citri.
abstract: A short-tailed polyhedral virus (ai) with a plaque morphology typical of temperate phages has been purified from the wall-less prokaryote Spiroplasma citri. Adsorption of the virus to host cells and isolated membranes was dependent on pH and divalent cation concentration. One-step growth curves and premature lysis experiments coupled with immunodetection of intracellular viral antigens showed a steady accumulation of viral products from 2 hr after infection. Mature virus was present after 3-4 hr. Virus release started after 5-6 hr and continued for a further 4-5 hr. The virus had antigens in common with other type 3 spiroplasma viruses and purified DNA hybridised to specific pieces of DNA from these related viruses. A physical map of the virus genome has been constructed. Unlike those of related viruses, the genome of ai can form noncovalently closed circles and multimers. The significance of this in relation to the biological properties of the virus is discussed.
authors.affiliation: Department of Virus Research, John Innes Institute, Colney Lane, Norwich NR4 7UH, England.
authors.forename: M J
authors.initials: MJ
authors.lastname: Dickinson
authors.forename: R
authors.initials: R
authors.lastname: Townsend
authors.forename: S J
authors.initials: SJ
authors.lastname: Curson