Recombinant viruses are the workhorse of modern neuroscience. Whether one would like to understand a neuron’s morphology, natural activity patterns, molecular composition, connectivity or behavioural and physiologic function, most studies begin with the injection of an engineered virus, often an adeno-associated virus or herpes simplex virus, among many other types. Recombinant viruses currently enable some combination of cell type-specific, circuit-selective, activity-dependent and spatiotemporally resolved transgene expression. Viruses are now used routinely to study the molecular and cellular functions of a gene within an identified cell type in the brain, and enable the application of optogenetics, chemogenetics, calcium imaging and related approaches. These advantageous properties of engineered viruses thus enable characterization of neuronal function at unprecedented resolution. However, each virus has specific advantages and disadvantages, which makes viral tool selection paramount for properly designing and executing experiments within the central nervous system. In the current Review, we discuss the key principles and uses of engineered viruses and highlight innovations that are needed moving forward.

重组病毒是现代神经科学的主力军。无论是想了解神经元的形态、自然活动模式、分子组成、连接性还是行为和生理功能，大多数研究都是从注射工程病毒开始的，通常是腺相关病毒或单纯疱疹病毒，以及许多其他类型. 重组病毒目前能够实现细胞类型特异性、回路选择性、活性依赖性和时空解析的转基因表达的某种组合。病毒现在通常用于研究大脑中已识别细胞类型中基因的分子和细胞功能，并使光遗传学、化学遗传学、钙成像和相关方法的应用成为可能。因此，工程病毒的这些有利特性能够以前所未有的分辨率表征神经元功能。然而，每种病毒都有特定的优点和缺点，这使得病毒工具的选择对于在中枢神经系统内正确设计和执行实验至关重要。在当前的评论中，我们讨论了工程病毒的关键原则和用途，并强调了向前发展所需的创新。