VIEW ARTICLE

Purification of Cocoa Necrosis Virus from Cocoa Leaves. D. Adomako, Research Biochemist, Cocoa Research Institute, P.O. Box 8, New Tafo, Ghana; G. K. Owusu(2), and K. K. Oduro(3). (2)Research Virologist, Cocoa Research Institute, P.O. Box 8, New Tafo, Ghana; (3)Lecturer in Biochemistry, Department of Biochemistry, University of Ghana, Legon, Ghana. Phytopathology 64:1325-1330. Accepted for publication 14 May 1974. DOI: 10.1094/Phyto-64-1325.

Cocoa necrosis virus (CNV) was isolated from infected cocoa (Theobroma cacao L.) leaves by precipitation of virus with 10% polyethylene glycol 6000 (PEG 6000), chromatography on Celite 545 using decreasing concns of polyethylene glycol as eluent, or by purification of resuspended PEG-precipitated virus by differential centrifugation. The problem of effectively removing host-plant materials from the mucilaginous extracts was overcome by the chromatography on Celite or by treating the crude extracts with 0.2% pectinase prior to precipitation of the virus with PEG. Both methods enabled further purification of virus by gel-filtration, but recovery of virus was better with the differential centrifugation procedure than with chromatography on Celite. Gel filtration with Sephadex G200 and Sepharose 4B (4% agarose) greatly enhanced the infectivity of preparations made from source material consisting largely of moderately necrotic leaves; infectivities of preparations made from highly necrotic leaves were not affected. This is attributed to removal of a high molecular wt inhibitor which presumably becomes degraded in the highly necrotic tissues. Purified preparations contained numerous isometric particles, 25-28 nm in diam. Some in vitro properties of the virus are described.