library_construction_protocol: Lungs were harvested on day 3, lung cells were isolated using the gentleMACS Dissociator (Miltenyi Biotec) according to the manufacturer's standard protocol. Sequencing was performed in paired-end mode (read1: 28 bp; read2: 90 bp) using a DNBSEQ-G400 sequencer (MGI Tech, Shenzhen, China).