Serological Relationships among Tombusviruses

Abstract
Serological differentiation indices (SDIs) based on serum titrations in agar-gel double diffusion tests were determined for all ten definitive tombusviruses known at present, namely artichoke mottled crinkle, carnation Italian ringspot, cymbidium ringspot, eggplant mottled crinkle, Moroccan pepper, pelargonium leaf curl, petunia asteroid mosaic, the BS3 and type strains of tomato bushy stunt, and tombus Neckar viruses. More than 2000 titrations using 222 antisera from 36 rabbits were done. The SDIs ranged from 1 to > 9, and all intermediate values were found. Simple trigonometry and computer methods were used to classify the results. There was no correlation between the serological relatedness of the particles of these viruses and the homology of their genome nucleic acids previously assessed by hybridization tests. In this respect they resemble the tymoviruses but not the tobamoviruses. The electrophoretic migration of the particles of 12 tombusviruses was studied in 1% agarose containing 20 mM-phosphate buffer pH 7.0. Some serologically indistinguishable tombusvirus strains migrated at different rates.