A variety of noncirculatively transmitted viruses have evolved a vector transmission strategy that involves, in addition to virions, virus-encoded proteins that are not constituents of virions. These "helpers" and the genes encoding them have been characterized for viruses in the genera Potyvirus and Caulimovirus. Several lines of evidence support the hypothesis that these helpers act by mediating retention of virions in regions of the vector's alimentary tract from which they subsequently can be egested to initiate an infection. The possible advantage this convergently evolved strategy could confer to noncirculatively transmitted virus quasispecies is discussed.

中文翻译：

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植物病毒的依赖辅助载体的传播。

多种非循环传播的病毒已经进化出一种载体传播策略，除了病毒体之外，还涉及不是病毒体组成的病毒编码蛋白。这些“辅助物”和编码它们的基因已经在波多病毒和花椰菜花叶病毒属中被表征为病毒。有几条证据支持以下假说：这些辅助分子通过介导病毒在食物消化道区域的滞留而起作用，随后可据此诱使它们启动感染。讨论了这种融合进化策略可能赋予非循环传播病毒准种的可能优势。