Early Transcriptome of Pseudomonas aeruginosa PAO1 Infected With vB_Pae_QDWS, a Short‐Latent Lytic Phage

ABSTRACT Phage adsorption, genome injection, and immediate activation of host genes are critical steps that determine whether phages can complete their infection cycle. Elucidating the early molecular dynamic network of phage‐host interactions is essential for understanding the dynamic balance between phage invasion and bacterial defense. In this study, Pseudomonas aeruginosa PAO1 was used as a model to investigate the early transcriptional responses during infection by lytic phage vB_Pae_QDWS, which features an extremely short latent period. Transcriptomic analysis at 0, 3, 6, and 20 min postinfection revealed a transient expression of early phage genes ( gp01 – gp08 , gp13 ). Concurrently, the host exhibited broad transcriptional reprogramming, particularly in genes related to receptors such as flagella, pili, and lipopolysaccharide (LPS) biosynthesis, as well as quorum‐sensing (QS) regulators including lasI , lasR , and rhlI . Correlation analyses revealed strong associations between specific early phage genes and host QS‐related genes. Notably, the early phage gene gp08 exhibited a strong negative correlation with the QS regulator lasR , implying a potential inhibitory interaction. This study highlights the critical role of early phage gene expression in the initial takeover of the host and demonstrates the host's rapid transcriptional response under phage pressure, offering new insights into phage–host interactions and phage‐based control strategies.