The paradigm that viruses can move directly, and in some cases covertly, between contacting target cells is now well established for several virus families. The underlying mechanisms of cell-to-cell spread, however, remain to be fully elucidated and may differ substantially depending on the viral exit/entry route and the cellular tropism. Here, two divergent cell-to-cell spread mechanisms are exemplified: firstly by human retroviruses, which rely upon transient adhesive structures that form between polarized immune cells termed virological synapses, and secondly by herpesviruses that depend predominantly on pre-existing stable cellular contacts, but may also form virological synapses. Plant viruses can also spread directly between contacting cells, but are obliged by the rigid host cell wall to move across pore structures termed plasmodesmata. This review will focus primarily on recent advances in our understanding of animal virus cell-to-cell spread using examples from these two virus families, and will conclude by comparing and contrasting the cell-to-cell spread of animal and plant viruses.

病毒可以在接触靶细胞之间直接移动，在某些情况下可以秘密移动的范例现在已经为几个病毒家族建立了良好的基础。然而，细胞间传播的潜在机制仍有待完全阐明，并且可能因病毒退出/进入途径和细胞趋向性而大不相同。在这里，举例说明了两种不同的细胞间传播机制：首先是人类逆转录病毒，它依赖于极化免疫细胞之间形成的瞬时粘附结构，称为病毒突触，其次是主要依赖于预先存在的稳定细胞接触的疱疹病毒，但也可能形成病毒突触。植物病毒也可以直接在接触细胞之间传播，但必须由刚性宿主细胞壁移动穿过称为胞间连丝的孔结构。