Anemone necrosis, a disease caused by a strain of tobacco ringspot virus

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Abstract
SUMMARY: A strain of tobacco ringspot virus (TRSV) was isolated from severely necrotic Anemone coronaria plants in Somerset in 1957, and was named anemone necrosis virus (ANV). ANV infected, by sap‐rubbing inoculation, fifty‐eight of 103 plant species tested, in twenty‐one out of thirty‐two families. Experimental infection of anemone plants induced symptoms of necrosis and die‐back, but less virulent than those seen in the field. The virus was cultured and assayed in Nicotiana clevelandii or N. tabacum. The in vitro properties in crude sap were: maximum infective dilution 1/125 to 1/10,000 according to the source plant; thermal inactivation point (10 min.) 70°C.; survival in vitro 21 but not 28 days at 18°C., and at least 12 weeks at 0°C. Preparations preserved by vacuum sublimation (freeze‐drying) were still infective after 5 years. Some N. tabacum plants could be freed from ANV by growing at 37°C. for 4–6 weeks.Although less easily than TRSV, ANV was purified by extraction of N. clevelandii leaves macerated for 1–5 days at 0°C. in butanol + phosphate buffer, followed by differential centrifugation. Purified preparations were highly infective, serologically active, gave specific light‐scattering zones in density‐gradient centrifugation, and contained numerous angular particles (c. 29 mμ diam.) in electron micrographs. Antisera to ANV and to TRSV had specific titres up to 1/16,384. The two viruses were serologically closely related, very similar in host range and symptoms, in vitro properties, density‐gradient zones and particle form; they differed principally in the ways in which they could be purified.Anemone necrosis disease is apparently localized in Britain and its incidence small.