BACKGROUND
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.
METHODS
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.
RESULTS
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.
CONCLUSIONS
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.
Chimeric antigen receptor (CAR)-T cell therapy targeting CD19 has demonstrated notable clinical efficacy in the treatment of B-cell acute lymphoblastic leukemia (B-ALL), but its wider clinical applicability is constrained by long manufacturing processes, substantial costs, and severe adverse events. A potentially safer and more accessible alternative is provided by CAR-Natural killer (CAR-NK) cell therapy. Currently, most CAR-NK cells are generated using viral transduction, which is labor-intensive and associated with risks of genomic integration. Electroporation of CAR-encoding mRNA provides a non-integrating alternative but results in only transient CAR expression. Circular RNA (circRNA), owing to its enhanced stability and prolonged protein expression capacity, has recently emerged as a promising alternative to linear mRNA. To overcome the limitations of transient mRNA expression, we generated circRNA using a Group II intron-mediated cyclization system incorporating a newly selected Coccidioides immitis-derived Group II intron. The newly established Coccidioides immitis-derived Group II intron circularization system efficiently generated circRNA and supported more durable EGFP expression than linear mRNA in both HEK293T and NK92 cells. Using this system, we successfully developed a circRNA-based CD19-targeted CAR-NK platform. CircRNA-engineered CD19-targeted CAR-NK92 cells maintained more durable CAR expression and showed stronger antitumor activity at later time points. In mouse models of B-ALL, circRNA-engineered CAR-NK92 cells demonstrated better tumor control and extended survival compared with their linear mRNA-engineered counterparts. These results support the potential of circRNA-based CAR-NK therapy as an effective approach for enhancing the safety and efficacy of cancer immunotherapy.
Qisheng Dong, Ying Liu, Na Chen et al.· International Immunopharmaco...· 0 citations