Detailed single-cell mapping of the transcriptional response to a virus infection driven by copy-back viral genomes.

The antiviral response to several clinically significant viruses, including respiratory syncytial virus and parainfluenza virus, is driven by copy-back viral genomes (cbVGs) generated during virus replication. However, the broader impact of cbVGs on the functional states of host cells remains undefined. Here, we developed a single-cell RNA-sequencing and computational framework to map cbVG-driven host responses during Sendai virus infection. Unsupervised profiling identified distinct transcriptional states throughout the course of infection, highlighting a shift from early antiviral signaling to later inflammatory and remodeling programs. Stratifying infected cells by cbVG status demonstrated that cbVG-positive cells initiate interferon and chemokine programs, which later spread to cbVG-negative cells. At later stages, cbVG-positive cells acquire additional signaling, cytoskeletal, transcriptional, and stress-adaptation programs, which are absent in cbVG-clean infection. This work defines the broader cbVG-driven layered and dynamic host response and provides a valuable high-resolution resource of the temporal cellular response to a virus infection.