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Serological Grouping of Tomato Ringspot Virus Isolates: Implications for Diagnosis and Cross-Protection. M. W. Bitterlin, Former graduate research assistant, Department of Plant Pathology, Cornell University, New York State Agricultural Experiment Station, Geneva 14456, Present address: BIOREBA AG, Gempenstrasse 27, CH-4008 Basel, Switzerland; D. Gonsalves, Professor, Department of Plant Pathology, Cornell University, New York State Agricultural Experiment Station, Geneva 14456. Phytopathology 78:278-285. Accepted for publication 9 September 1987. Copyright 1988 The American Phytopathological Society. DOI: 10.1094/Phyto-78-278.

This study was done to determine the serological relationships between a wide range of tomato ringspot virus isolates and to identify a model system for studies of cross-protection. Polyclonal antisera were prepared to the “standard isolates”: Chickadee, grape yellow vein, peach yellow bud mosaic, and West Virginia-18. Thirty-three isolates, collected from different areas of North America and Europe, were then compared by serology and a limited host range. The isolates could be classified into five serogroups by direct double-antibody sandwich enzyme-linked immunosorbent assay, using the antisera to the standard isolates. None of the antisera was able to detect all of the isolates. Indirect enzyme-linked immunosorbent assay was less specific but only suitable with purified or partially purified antigen. Agar double-diffusion tests confirmed that the standard isolates were related but not identical. Some isolates could be clearly distinguished by their virulence on Nicotiana benthamiana. Chickadee and peach yellow bud mosaic were found to be serologically and biologically distinct isolates that provide an excellent system for studies of cross-protection with tomato ringspot virus.