cDNA cloning and sequencing of 54kDa fragment of the 75kDa readthrough protein gene from beet necrotic yellow vein virus.

With viral RNA extracted from purified beet necrotic yellow vein virus (BNYVV) isolated from Inner Mongolia, the first strand of cDNA encoding a 54kDa fragment of the 75kDa readthrough protein on the RNA2 was synthesized by reverse transcription. A double-strand cDNA fragment of 1.5 kb was obtained after 30 cycles of PCR amplification. The fragment was ligated into and mapped on pGEM-7Zf(+). The result of sequence analysis shows that the 54kDa readthrough domain is 1509 nucleotides (nt). Compared with F13 isolate, the fragment shares 94.97% identity in terms of nucleotides with 3 nt deletion and 96.42% identity of deduced amino acids.