Comparison of Two Strains of Kalanchoë Latent Virus, Carlavirus Group

Abstract

A carlavirus isolated from Kalanchoe blossfeldiana ''Texas Sunset'' and designated KV-2 was compared with a previously characterized carlavirus isolated from cv. Rotkappchen and designated KV-1. The isolates had similar host ranges, thermal inactivations (.apprx. 75.degree. C), buoyant densities (1.30 g/cm3) and capsid protein MW (33,000-34,000 daltons). KV-2 was distinguished from KV-1 in that KV-2: systemically infected Chenopodium spp. that were only locally infected by KV-1; had a normal length that was .apprx. 30 nm longer than that of KV-1; and was degraded by reagents such as 1% Triton X-100, 5 mM EDTA and chloroform CCl4 that did not degrade KV-1. KV-2 was purified from C. quinoa by clarification of phosphate-buffered crude sap extracts with 1,1,2-trichloro-1,2,2-trifluoroethane (Freon), precipitation with 6% polyethylene glycol and centrifugation on 10-40% linear CsCl density gradients. Sodium dodecyl sulfate degraded KV-1 and KV-2 formed lines of partial fusion in Ouchterlony gel double diffusion tests. Isolate-specific antibodies were found in each homolgous antiserum in intragel cross-absorption tests. Both isolates reacted in indirect ELISA (enzyme-linked immunosorbent assay) with antisera to carnation latent, chrysanthemum B, lily symptomless and potato S viruses, but not to elderberry A, hippeastrum latent, red clover vein mosaic or narcissus latent viruses. Since only minor differences were found in most of the properties of the 2 viruses, KV-1 and KV-2 are concluded to be strains of the same carlavirus, here designated kalanchoe latent virus.