Viral cell-to-cell spread: Conventional and non-conventional ways.

A critical step in the life cycle of a virus is spread to a new target cell, which generally involves the release of new viral particles from the infected cell which can then initiate infection in the next target cell. While cell-free viral particles released into the extracellular environment are necessary for long distance spread, there are disadvantages to this mechanism. These include the presence of immune system components, the low success rate of infection by single particles, and the relative fragility of viral particles in the environment. Several mechanisms of direct cell-to-cell spread have been reported for animal viruses which would avoid the issues associated with cell-free particles. A number of viruses can utilize several different mechanisms of direct cell-to-cell spread, but our understanding of the differential usage by these pathogens is modest. Although the mechanisms of cell-to-cell spread differ among viruses, there is a common exploitation of key pathways and components of the cellular cytoskeleton. Remarkably, some of the viral mechanisms of cell-to-cell spread are surprisingly similar to those used by bacteria. Here we summarize the current knowledge of the conventional and non-conventional mechanisms of viral spread, the common methods used to detect viral spread, and the impact that these mechanisms can have on viral pathogenesis.

病毒生命周期中的一个关键步骤是传播到新的靶细胞，这通常涉及从受感染细胞释放新的病毒颗粒，然后这些病毒颗粒可在接下来的靶细胞中引发感染。虽然释放到细胞外环境中的无细胞病毒颗粒对于远距离传播是必要的，但这种机制存在一些弊端。这些弊端包括免疫系统成分的存在、单个颗粒感染成功率低以及病毒颗粒在环境中相对脆弱。对于动物病毒，已经报道了几种直接的细胞间传播机制，这些机制可以避免与无细胞颗粒相关的问题。许多病毒可以利用几种不同的直接细胞间传播机制，但我们对这些病原体的不同使用方式的了解还很有限。尽管病毒之间细胞间传播的机制不同，但都普遍利用了细胞骨架的关键通路和成分。值得注意的是，一些病毒的细胞间传播机制与细菌所使用的机制惊人地相似。在此，我们总结了目前关于病毒传播的常规和非常规机制的知识、用于检测病毒传播的常用方法以及这些机制对病毒致病性的影响。