CROSS-PROTECTION STUDIES BETWEEN STRAINS OF SUGARCANE MOSAIC, MAIZE-DWARF MOSAIC, JOHNSONGRASS MOSAIC, AND SORGHUM MOSAIC POTYVIRUSES

Cross-protection was studied between strains of viruses comprising the sugarcane mosaic virus (SCMV) subgroup, namely Johnsongrass mosaic, m aize dwarf mosaic, sorghum mosaic, and SCMV, in 53 different combinati ons using differential hosts and Western blot immunoassays. Cross-prot ection occurred only between SCMV-MDB and SCMV-BC when the former was inoculated first and the latter used as the challenge strain, but neit her vice versa nor in any other combinations including the 19 that inv olved recognized strains of the one virus, SCMV. The unidirectional pr otection between SCMV-MDB and SCMV-BC and the negative cross-protectio n results between other strains of SCMV appear to correlate with diffe rent sequence motifs present in the hypervariable region of the coat p rotein N-terminus of the SCMV strains.