Ribosome profiling reveals translational dynamics between an archaeal virus and its host

Host-virus interactions remain poorly understood in archaea, whose information processing systems harbor a mosaic of bacterial and eukaryotic features. Here, we used complementary multiomics to investigate interactions between Haloferax tailed virus 1 (HFTV1) and the halophilic archaeon Haloferax gibbonsii ( Hg ), capturing global translational and transcriptional dynamics across the infection cycle. This revealed co-regulatory expression patterns across HFTV1 and Hg genes. Post-transcriptional regulation was observed for several early HFTV1 genes and the late HFTV1 gene gp17 , and the HFTV1 tRNA co-sedimented with Hg ribosome complexes. Infection reshaped the translational landscape of Hg , causing a slow decline in information processing activity, a complex transcriptional response, and amino acid starvation. An unannotated Tat-dependent fimbrial system of Hg was co-regulated with early HFTV1 genes and was correlated with increased biofilm formation, suggesting a potential antiviral defense system. These findings provide high-resolution insight into archaeal host-virus interactions at the evolutionary interface between bacteria and eukaryotes.