
Full text loading...
Citrus tristeza virus (CTV) contains approximately 20000 bases of positive-sense ssRNA, encapsidated by a coat protein of approximately 25000 M r that has previously been reported to consist of at least two size variants, cp1 and cp2. In the present study, a cDNA library of the T36 isolate of CTV was prepared in a protein expression vector and screened with a polyclonal antibody against the coat protein. Five immuno-positive clones produced proteins in Escherichia coli that reacted with monoclonal as well as polyclonal antibodies to the CTV coat protein. Nucleotide sequence analysis of a region common to the five clones revealed the presence of a 669 nucleotide open reading frame flanked by numerous in-frame termination codons. The encoded protein has a predicted M r of 24909 and an amino acid composition consistent with that previously reported for the CTV coat protein. Comparison of the predicted amino acid sequence of the coat protein with the amino-terminal sequences of cp1 and cp2 indicated that these coat protein species arise from the same primary translation product, as a result of post-translational proteolysis at sites approximately 12 to 15 and 26 amino acids from the amino terminus respectively. These results are the first reported cloning and sequencing of a CTV gene and provide evidence that CTV may be translated using subgenomic RNA.
Article metrics loading...
Full text loading...
References
Data & Media loading...