Serological Studies on the Relationships of Some Isometric Viruses of Gramineae

Abstract

SUMMARY Particles of 17 isolates of viruses from Gramineae were purified and the virus relationships assessed by different serological techniques. From the reaction end-points of antisera in agar gel double diffusion tests the serological differentiation indices of reciprocal tests were calculated. These indices were used to construct a scheme of serological interrelationship. Spur formation tests were used to distinguish between closely related, non-identical viruses. The isolates were shown to belong to four groups, one of which (the cocksfoot mild mosaicpanicum mosaic virus group) contains most of the isolates and can be subdivided into two main clusters (typified by cocksfoot mild mosaic and panicum mosaic viruses, respectively). Additional information was obtained by immunoelectrophoresis of the viruses with their homologous antisera and by the determination of the mol. wt. of the coat protein subunits using SDS-polyacrylamide gel electrophoresis. The data obtained by both methods agree with the above mentioned results, although some minor differences were found between the immunoelectrophoretic patterns of panicum mosaic virus and its relatives and also the three isolates of Cynosurus mottle virus. Reversed rocket electrophoresis did not provide any information of use in virus grouping. Brome mosaic virus did not react with the antisera to the 17 viruses, but tobacco mosaic virus reacted weakly with all the antisera and also with one of the antisera to brome mosaic virus. These and other recently published results are discussed.