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Etiology

Purification and Serology of Papaya Ringspot Virus. D. Gonsalves, Department of Plant Pathology, New York State Agricultural Experiment Station, Cornell University, Geneva 14456; M. Ishii, Department of Plant Pathology, University of Hawaii, Honolulu 96822. Phytopathology 70:1028-1032. Accepted for publication 25 April 1980. Copyright 1980 The American Phytopathological Society. DOI: 10.1094/Phyto-70-1028.

An isolate of papaya ringspot virus (PRV-HA) obtained from Hawaii was purified, and antiserum to the virus was produced. Papaya infected with PRV-HA had severely distorted leaves, while infected zucchini squash showed intense mosaic and some leaf distortion which was similar to that caused by watermelon mosaic virus 1 (WMV-1). Infectivity of PRV-HA in zucchini leaves was highest 21–25 days after inoculation. Virus was purified by Cs₂SO₄ density gradient centrifugation after clarification of tissue extracts by chloroform/carbon tetrachloride and concentration of virus particles by polyethylene glycol. Aggregation of virus particles was reduced by using EDTA in extraction and resuspension buffers. Antiserum produced to isolated capsid protein of PRV-HA reacted with PRV in sodium dodecyl sulfate (SDS)-immunodiffusion tests. Antiserum produced to “intact” particles of PRV-HA did not generally react with PRV in SDS-immunodiffusion tests but gave strong reactions in enzyme-linked immunosorbent assay (ELISA) tests. Sensitivity of ELISA was increased markedly if high molarity buffer (>0.2 M potassium phosphate) or EDTA was used to extract virus from tissues. With antisera to PRV-HA, no serological difference could be detected between PRV-HA, a Florida isolate of PRV, and WMV-1. Antisera to PRV-HA did not react to three other viruses in the potyvirus group.