Caught in the act of copying: The genomes of double-stranded RNA (dsRNA) viruses consist of about a dozen dsRNA segments enclosed by a protein coat. Inside the host cell, the coat remains intact, and the dsRNAs have to replicate within the coat. Liu and Cheng used cryo–electron microscopy of cypovirus particles to catch the dsRNAs in the act of being copied. The structures revealed that the RNA formed a liquid-crystalline array on which viral enzymes carry out multiple rounds of transcription to replicate the viral genome. Science , this issue p. 1347

Focusing in on herpesvirus: The herpesvirus family includes herpes simplex virus type 1 (HSV-1), which causes cold sores, and type 2 (HSV-2), which causes genital herpes. Herpesviruses comprise a large DNA genome enclosed in a large and complex protein cage called a capsid (see the Perspective by Heldwein). Dai and Zhou used electron microscopy to determine a high-resolution structure of the HSV-1 capsid bound to the tegument proteins that occupy the space between the capsid and the nuclear envelope. The structure suggests how these components may play a role in viral transport. Yuan et al. describe a higher-resolution structure of an HSV-2 capsid, providing insight into how the shell assembles and is stabilized. Science , this issue p. eaao7298 , p. eaao7283 ; see also p. 34

Significance: Many double-stranded DNA (dsDNA) viruses, including the tailed dsDNA bacteriophages and herpesviruses, use molecular machines at a unique vertex of the capsid for genome delivery. Bacteriophage T7 provides a tractable model for the study of dsDNA viruses. Here, we report the structure of the mature bacteriophage T7, as well as the structures of the full and empty T7 particles in complex with their cell receptor lipopolysaccharide. The symmetry-mismatch machines at the vertex, including internal ejection proteins, have been resolved at near-atomic resolutions in our structures. The structures of the T7 particles at different stages reveal a series of structural rearrangements after viral genome delivery.

The optical imaging guided tumor vessels and vascular malformation visualization by using the second near infrared emission beyond 1500 nm (NIR-II) is emerged as the next generation fluorescence imaging technique for early tumor diagnosis and identification of tumor-associated vascular features. On the other hand, developing theranostic probes for NIR-II imaging guided photothermal therapy (PTT) is of great significance, which is rarely explored. Herein, a high performance theranostic nanoplatform based on the core-shell structured NaLuF₄ nanorods@polydopamine (denoted as NRs@PDA) by integrating the new advanced NIR-II imaging beyond 1500 nm with PTT function was developed for tumor-associated vascular malformation visualization and imaging-guided PTT.