Engineered Biomolecular Condensates Limit Tobacco Mosaic Virus Accumulation and Symptom Development.

Artificial condensates formed by liquid-liquid phase separation (LLPS) have been extensively studied in the field of synthetic biology for their ability to control cellular functions in a reversible and tunable manner. Although cellular condensates can restrict viral accumulation, the potential to employ LLPS as a platform for targeted antiviral strategies remains understudied. Here, we engineered tobacco mosaic virus (TMV) to harbour MS2 bacteriophage hairpins that are specifically bound by the MS2 coat protein (MCP). Using well-studied intrinsically disordered regions (IDRs) as scaffolds, we engineered artificial condensates that could target MS2-tagged TMV, inhibiting TMV accumulation up to fivefold following transient expression in Nicotiana benthamiana. TAR DNA-binding protein 43 (TDP-43)-based condensates inhibited MS2-tagged virus accumulation by over twofold, independent of the global translational repression observed during condensate expression. Following manual inoculation of MS2-tagged TMV onto leaves transiently expressing TDP-43:MCP condensates, systemic virus accumulation was reduced by over 10-fold, which was associated with a significant decrease in symptom severity. These results provide a foundation for developing artificial biomolecular condensates to mitigate plant virus accumulation and disease severity.