Identification and Geographic Distribution of Serotypes of Potato Virus Y

From a panel of 10 monoclonal antibodies (MAbs) prepared against specific isolates representing the three recognized strain groups of potato virus Y (PVY), i.e., common (PVY^O), tobacco veinal necrosis (PVY^N), and stipple streak (PVY^C), seven were selected for serotype analysis. These MAbs were tested for reactivity with 52 PVY strains representing all three strain groups from an international collection. Within the PVY^N strain group, five serotypes were identified and designated N₁ to N₅. The PVY^O strain group was more diverse, and nine serotypes were defined and designated O₁ to O₉. Only one serotype, designated C₁, was defined) within the PVY^C strain group. The same panel of MAbs was used to test 632 PVY samples collected from potato seed certification plots in North America. Although no PVY(N) serotypes were found, all of the PVY^O serotypes were identified, and several samples, tentatively assigned to the C₁ serotype, were found.