Baulcombe D C, Lloyd J, Manoussopoulos I N, Roberts I M, Harrison B D
Sainsbury Laboratory, Norwich Research Park, Colney, U.K.
J Gen Virol. 1993 Jul;74 ( Pt 7):1245-53. doi: 10.1099/0022-1317-74-7-1245.
A British isolate of potato aucuba mosaic potexvirus (PAMV) was transmitted by aphids (Myzus persicae) which had fed previously on a source of potato Y potyvirus (PVY). Nucleotide sequence analysis of the PAMV coat protein gene indicated that amino acid residues 14 to 16 from the N terminus of the coat protein have the sequence DAG, which is also found in the coat proteins of potyviruses and is required for their aphid transmissibility. A recombinant virus isolate (TXPA7) was produced in which a segment of the coat protein gene of PAMV encoding the 40 N-terminal amino acids was inserted in the genome of potato X potexvirus (PVX) in place of the segment encoding the 28 N-terminal amino acids of PVX coat protein. This isolate, and a second similar recombinant (TXPA5) in which the DAG motif was changed to YTS, were mechanically transmissible to intact plants, in which they caused slightly milder symptoms than PVX. Particles of TXPA7 reacted in immunosorbent electron microscopy with PVX- and PAMV-specific antibodies and so were antigenically distinguishable from PAMV and PVX particles, which reacted only with their homologous antibody, and from TXPA5 particles, which reacted only with the PVX antibody. Recombinant TXPA7 was transmitted by aphids that had already fed on a source of PVY whereas TXPA5 and PVX were not. TXPA7 was not transmitted by aphids that had not fed on a PVY source. It is concluded that (i) the potyvirus-dependent aphid transmissibility of PAMV results from possession of a domain which includes the DAG motif and is located near the N terminus of the virus coat protein, and (ii) potyvirus-dependent aphid transmissibility can be conferred on PVX, a non-aphid-borne potexvirus, by substituting this domain for the N-terminal part of its coat protein.
一株英国分离的马铃薯奥古巴花叶马铃薯X病毒（PAMV）可由先前取食过马铃薯Y病毒（PVY）的蚜虫（桃蚜）传播。对PAMV外壳蛋白基因的核苷酸序列分析表明，外壳蛋白N端第14至16位氨基酸残基的序列为DAG，这一序列也存在于马铃薯Y病毒属病毒的外壳蛋白中，且是其蚜虫传播性所必需的。构建了一种重组病毒分离株（TXPA7），其中PAMV外壳蛋白基因编码40个N端氨基酸的片段被插入到马铃薯X病毒（PVX）基因组中，取代了编码PVX外壳蛋白28个N端氨基酸的片段。该分离株以及第二种类似的重组体（TXPA5，其中DAG基序被改为YTS）可通过机械接种传播到完整植株上，它们在植株上引起的症状比PVX略轻。在免疫吸附电子显微镜下，TXPA7的病毒粒子与PVX和PAMV特异性抗体发生反应，因此在抗原性上可与仅与同源抗体反应的PAMV和PVX病毒粒子以及仅与PVX抗体反应的TXPA5病毒粒子区分开来。重组体TXPA7可由已经取食过PVY的蚜虫传播，而TXPA5和PVX则不能。未取食PVY来源的蚜虫不能传播TXPA7。由此得出结论：（i）PAMV依赖马铃薯Y病毒属病毒的蚜虫传播性是由于拥有一个包含DAG基序且位于病毒外壳蛋白N端附近的结构域；（ii）通过将该结构域替换其外壳蛋白的N端部分，可使非蚜虫传播的马铃薯X病毒获得依赖马铃薯Y病毒属病毒的蚜虫传播性。
