Molecular cloning and nucleotide sequencing of the 3'-terminal region of a South African isolate of ryegrass mosaic virus RNA and in vitro expression of the coat protein gene.

The 2094 nucleotides at the 3'-terminus of a South African isolate of ryegrass mosaic virus (RGMV) was cloned and sequenced. Two putative polyprotein cleavage sites were found: Q/L and E/A, both of which are novel in the Potyviridae. The RGMV-SA cDNA was cloned into an expression vector, pUEX, and a fusion protein of 185 kDa was obtained which reacted strongly to anti-RGMV-SA antiserum. Alignment of the predicted amino acid sequence of RGMV-SA with those of other Potyviridae members showed limited identity, indicating that RGMV-SA is a definite and distinct virus.