CAPSID PROTEIN-PROPERTIES OF COWPEA APHID-BORNE MOSAIC-VIRUS AND BLACKEYE COWPEA MOSAIC-VIRUS CONFIRM THE EXISTENCE OF 2 MAJOR SUBGROUPS OFAPHID-TRANSMITTED, LEGUME-INFECTING POTYVIRUSES

study of the capsid proteins of different legume-infecting potyviruses using specific monoclonal antibodies on immunoblots of crude extracts from infected plants revealed that cowpea aphid-borne mosaic virus (C AMV) and blackeye cowpea mosaic virus (BICMV) have coat protein M(r). values of 32K and 35K, respectively. Immunoblot comparisons of BlCMV, peanut stripe mosaic virus (PStV), bean common mosaic virus (BCMV) and azuki bean mosaic virus (AzMV) revealed equal reactivity of their 35K coat proteins. Similar comparisons between CAMV and the necrotic stra in of BCMV (isolate NL3) showed a serological relationship between the ir 32K coat proteins, results providing the first evidence of a possib le similarity between CAMV and BCMV NL3. Peptides from trypsin digests of the coat proteins of several of these legume-infecting potyviruses were analysed by HPLC. Comparison of the peptide profiles confirmed t he serological results in distinguishing the two subgroups. Peptide pr ofiles of coat protein from BlCMV, PStV, AzMV and BCMV were almost ide ntical, results suggesting that they could be considered as strains of one virus. In contrast, peptide profiles of various CAMV serotypes an d BCMV NL3 were distinct from the first group and exhibited limited si milarities to each other.