A receptor-Fc based SFV replicon Trim-Away platform for targeted viral protein degradation

Developing effective antiviral strategies is urgently needed during global viral pandemics. Traditional approaches, including small-molecule inhibitors, neutralizing antibodies, and RNA interference (RNAi), often face challenges such as drug resistance, limited specificity, and inefficient delivery. These limitations highlight the pressing need for innovative strategies focused on the targeted degradation of viral proteins.

We developed an optimized Trim-Away system employing a receptor-Fc fusion protein strategy. This system integrates the E3 ubiquitin ligase TRIM21 with engineered receptor-Fc proteins to ensure highly specific recognition and intracellular degradation. A key innovation is the use of the Semliki Forest virus (SFV) self-amplifying replicon (pSFV). This platform enables sustained and robust expression of the Trim-Away components. Furthermore, this plasmid-based delivery eliminates the need for protein purification, thereby streamlining the process and improving delivery efficiency.

The system effectively degrades diverse viral targets. Specifically, it successfully degraded the spike proteins of both wild-type SARS-CoV-2 and its Omicron variant. It also targeted adeno-associated virus (AAV) capsid proteins. In vivo assays further confirmed that the self-amplifying replicon markedly reduces AAV-encoded luciferase expression. These data demonstrate that the system maintains high potency even at low dosages.

Our findings demonstrate that the pSFV-driven Trim-Away system is a powerful tool for viral protein degradation. The receptor-Fc strategy provides a significant advantage against rapidly mutating viruses. This study establishes a versatile and adaptable platform for future antiviral intervention.