Evidence that cowpea aphid-borne mosaic and blackeye cowpea mosaic viruses are two different potyviruses

The immunoreactivity of a panel of polyclonal antibodies and monoclonal antibodies (MAbs) raised against African isolates of potyviruses from cowpea and African yam bean was examined in ELISAs. A serological study including reference isolates followed by further characterization in differential hosts resulted in separation of the potyviruses into two distinct serogroups, one containing blackeye cowpea mosaic virus (BlCMV) and the other containing cowpea aphid-borne mosaic virus (CAMV). Using biotin-labelled MAbs, the BlCMV isolates were further subdivided into two serotypes and the CAMV isolates into five serotypes. Because both BlCMV and CAMV induce a very similar mosaic disease in cowpea, different ELISA procedures using mixed MAbs were evaluated and a single protocol was developed which allowed reliable diagnosis of both viruses.