Date of Award

1994

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Biology

Abstract

Cowpea mottle virus (CPMoV) is a small isometric plant virus which causes severe diseases on cowpea plants. At present, it is a proposed member of Tombusviridae, carmovirus group according to some of its biophysical-chemical properties. In this study, the positive strand RNA of CPMoV composed of 1,029 nucleotides was clone and sequenced. Comparison of the nucleotide and the deduced amino acid sequences of CPMoV to those of other viruses revealed significant sequence homology to the sequences of Tombusviridae, especially the carmovirus group. The deduced amino acid sequence of the second major open reading frame (ORF2), the putative RNA replicase or part of it, has 53% and 41% sequence homology to the replicases of carmovirus and tombusvirus. These data support the assignment of CPMoV to the Tombusviridae, carmovirus group. The 1.5 kb RNA replicase gene (ORF2) of CPMoV was cloned into the expression vector pGEX-2T for expression as a fusion protein with glutathione S-transferase (GST). However, the recombinant fusion vector failed to express the 83 kD fusion protein. The possible reasons for the failure are discussed.

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