SEROLOGICAL AND BIOLOGICAL VARIABILITY AMONG PAPAYA RINGSPOT VIRUS TYPE-W ISOLATES IN FLORIDA

Six distinct monoclonal antibodies (MAbs) were obtained to the viral structural protein of a Florida isolate of papaya ringspot virus type-W (PRSV-W). These MAbs were distinguished by their reactivity in indirect ELISA with 10 Florida isolates of PRSV-W, five additional isolates of PRSV-W, and with single isolates of the papaya strain of PRSV (PRSV-P) and a strain of PRSV from Guadeloupe (PRSV-T). MAb-1 and MAb-2 reacted with all 15 of the PRSV-W isolates and with PRSV-P. MAb-1 reacted with PRSV-T but MAb-2 did not. MAb-3 and MAb-4 reacted with eight of the 10 Florida isolates and with the other five isolates of PRSV-W. Neither MAb-3 nor MAb-4 reacted with PRSV-T. MAb-4 reacted with PRSV-P but MAb-3 did not. MAb-5 reacted with seven of the 10 Florida isolates of PRSV-W, the other five isolates of PRSV-W, with PRSV-P, and with PRSV-T. MAb-6 reacted only with the PRSV-W isolate used for immunization. When the PRSV isolates in this study were inoculated to different melon (Cucumis melo) cultivars, three biological variations were seen among the three isolates of PRSV-W that did not react with MAb-5. Isolate 2030, like the 12 other isolates of PRSV-W, gave compatible reactions in Edisto 47 and Vedrantais. Isolate 2052 gave incompatible reactions in Edisto 47 and compatible reactions in Vedrantais. Isolate 2040, like PRSV-T, gave incompatible reactions in both Edisto 47 and Vedrantais. The Florida isolates 2030, 2052, and 2040 also did not react with the Agdia "potyvirus group" MAb. The remaining PRSV-W isolates did react with this MAb. Our results indicate that the Florida population of PRSV-W is antigenically and biologically variable. This information has implications for the diagnosis and control of this virus in Florida.