A Potent Inhibitor of Human Cytomegalovirus Infection Works Post-Entry Specifically in Differentiating Myelo-Monocytic Cells

Human cytomegalovirus (HCMV) remains an important medical problem in multiple patient settings despite the availability of antivirals. In part, this is linked to resistance, cost and restrictions on use in several patient settings. More generally, it remains attractive to increase our arsenal of anti-viral approaches to target HCMV. We previously characterized a potent inhibitor of HCMV infection, DIDS, that displays cysteine reactivity, allowing it to bind virions and neutralize HCMV infection of fibroblasts. We now show that DIDS is inhibitory to cell-free and cell-associated infection of multiple cell types, including cells of the haematopoietic lineage-cells important for latency and dissemination. Consistent with this broad activity, DIDS partially inhibited gB (but not SARS-CoV-2 spike) fusion activity. Intriguingly, further characterization of DIDS activity in myeloid cells revealed that, unlike in all other cell types, DIDS blocked a post-entry event in CD14+ monocytes and also dendritic cell derivatives. Despite viral entry, entry was largely silent, with a failure to activate innate immunity and cell survival pathways known to be activated by HCMV. In contrast, HCMV infection was observed to activate host miRNA expression in CD14+ cells, suggesting a DIDS-insensitive viral function was responsible or, alternatively, that host miRNA expression is a potential anti-viral response to viral internalization. Thus, we report the further characterization of a broad-acting inhibitor of HCMV infection, which may also prove a useful tool to study unique events for the infection of monocytic cells by HCMV-a cell type that is crucial for HCMV dissemination and pathogenesis in vivo.