Genetic stability of recombinant potato virus X virus vectors presenting foreign epitopes

We investigated the genetic stability of recombinant potato virus X vectors presenting beet necrotic yellow vein virus (BNYVV) epitopes. Following N-terminal PVX coat protein (CP) fusion of the BNYVV epitopes, we inoculated Nicotiana benthamiana plants with recombinant (r)PVX and carried out five serial passages through systemically-infected plants. RT-PCR investigation of the BNYVV epitope sequences revealed the accumulation of several point mutations and deletions, predominantly affecting positively-charged residues. A comparison of the isoelectric point (pI) values and charges of the wild type and rCPs showed that the initial high rCP pI values had changed to values closer to that of the wild-type CP.