VIEW ARTICLE

Physiology and Biochemistry

Purification, Characterization, and Immunological Analysis of Nuclear Inclusions Induced by Bean Yellow Mosaic and Clover Yellow Vein Potyviruses. C. -A. Chang, Plant Pathology Department, University of Florida, Gainesville, Florida 32611, Present address: Department of Plant Pathology, Taiwan Agriculture Research Institute, Taichung, Taiwan, Republic of China; E. Hiebert, and D. E. Purcifull. Plant Pathology Department, University of Florida, Gainesville, Florida 32611. Phytopathology 78:1266-1275. Accepted for publication 2 March 1988. Copyright 1988 The American Phytopathological Society. DOI: 10.1094/Phyto-78-1266.

The nuclear inclusions (NI) induced by the PV-2 isolate of bean yellow mosaic virus (BYMV-PV-2) and the Pratt isolate of clover yellow vein virus (CYVV-P) were partially purified by treating infected tissue extracts with Triton X-100 followed by low-speed centrifugations. Purified NI from both viruses had cubic symmetry, but from the surface view the NI induced by BYMV-PV-2 were square-shaped, while those induced by CYVV-P were diamond-shaped. The NI of both viruses contained two distinct types of protein monomers with estimated M_r of 54,000 (54K) and 49K for BYMV-PV-2 and 60K and 49K for CYVV-P. The large NI monomers of both viruses were antigenically and chemically distinct from their respective small NI monomers. The NI proteins also were antigenically distinct from cylindrical inclusion and capsid proteins. A 98K protein and a 100K protein were consistently associated with NI preparations of BYMV-PV-2 and CYVV-P, respectively. These high M_r proteins were shown by immunological analyses and by peptide mapping to be polyproteins that contained sequences of both the large and the small NI monomers. Antisera prepared against SDS-dissociated NI proteins reacted specifically with NI in immunofluorescence studies of infected tissues. The large NI protein monomers of tobacco etch virus (TEV), BYMV-PV-2, and CYVV-P were serologically closely related to each other, while the small NI protein monomers of these three viruses were more viral specific as determined by SDS-immunodiffusion and by immunoprecipitation tests. In the cases of nine out of 14 potyviruses, extracts from infected tissues gave positive reactions for large NI protein-related antigens by indirect ELISA.