Updated project metadata. Host factors are essential for efficient amplification of Dengue virus (DENV), yet the current knowledge of these cellular proteins remains limited. Here, we used quantitative thiouridine cross-linking mass spectrometry (qTUX-MS) to cross-link proteins to viral RNA during a live DENV infection in cell culture. We identified 79 novel host proteins that have not been previously implicated in DENV infection, and demonstrated the reliability of qTUX-MS by validating a subset of these factors. Analysis of proteome changes revealed critical pathways up- and down-regulated during DENV infection, while the levels of qTUX-MS identified factors remained largely unchanged. Knockdown of HMCES, RBMX and hnRNP F reduced the levels of both intracellular viral RNA and DENV titers, suggesting roles in viral amplification prior to packaging and release. In contrast, knockdown of hnRNP M or NONO caused a dramatic drop in viral titers without impacting viral RNA accumulation, indicating a role downstream of DENV replication. Importantly, none of these five host factors were essential for cell viability or amplification of an unrelated virus, adenovirus, demonstrating that knockdown of these host factors did not reduce cell fitness for viral amplification. Thus, qTUX-MS can be used to identify host factor interactions for any RNA virus.