T311 Intron Expression System
A proprietary intron fragment and hybrid promoter system engineered for durable, high-level transgene expression while preserving AAV packaging capacity for advanced regulatory elements.
-
Advanced Expression for Safer, More Effective Gene Therapy
The T311 fragment is Elisigen’s proprietary gene expression technology, engineered to overcome limited durability and the finite packaging capacity of AAV vectors. Through systematic sequence engineering, we screened the naturally occurring human EF-1α intron. By preserving only essential RNA splicing domains and truncating the internal length, we successfully isolated a highly condensed 95-base pair fragment. This EF-1α-derived fragment enables intron-mediated enhancement (IME), robustly amplifying gene expression in eukaryotic cells. Crucially, it drastically reduces the native intron length, maximizing effective payload capacity within the AAV vector. Its modular design also ensures seamless compatibility with diverse promoters, enabling tailored therapeutic configurations. -
Engineered for Ocular Gene Therapy: CAT311
Building upon the T311 fragment, we developed the CAT311 promoter—the expression system driving our lead ocular program, NG101. CAT311 is an optimized hybrid architecture integrating the CMV enhancer and chicken β-actin core promoter with our T311 intron fragment. The industry-standard CAG promoter occupies ~1,724 base pairs, severely limiting AAV packaging capacity. By integrating T311, we condensed CAT311 to just 899 base pairs— approximately half the size of CAG. This freed-up space allows the inclusion of advanced regulatory elements, like miR-142-3p target sequences, to suppress immune responses. Furthermore, CAT311 is deliberately designed with fewer CpG sites, reducing the risk of TLR9 activation and mitigating unwanted ocular inflammation. -
Proven Superiority in Preclinical Models
The differentiated performance of CAT311 has been validated across distinct preclinical ocular models. In mice, CAT311 drove therapeutic transgene expression more than three times higher than the conventional CAG promoter. Its superior long-term durability was also confirmed, sustaining robust expression over a 51-week observation period.
