TrialLineage Concept
Viral vectors / AAV
Viral vectors are engineered viruses stripped of their ability to cause disease and repurposed to deliver therapeutic genes into human cells. Adeno-associated virus (AAV) has become one of the most widely used vectors in gene therapy because of its safety profile, ability to transduce non-dividing cells, and long-term gene expression without integrating into the host genome.
In plain language
What is a viral vector?
Viruses are naturally efficient at entering cells and delivering genetic material. Scientists realized they could harness this ability by removing the viral genes that cause disease and replacing them with a therapeutic gene. The result is a “vector” — a delivery vehicle that carries genetic cargo into cells without causing infection.
AAV is a small, non-pathogenic virus that was first discovered as a contaminant in other virus preparations. It infects humans without causing known disease, which made it an attractive starting point for engineering. Different AAV serotypes (variants) target different cell types, allowing researchers to choose vectors suited to specific organs.
Why viral vectors matter
Without a safe and effective delivery mechanism, gene therapy remains a theoretical concept. The development of AAV vectors solved a critical bottleneck: how to get genetic material into target cells reliably, with minimal immune response, and with durable expression.
The choice of vector determines safety, tissue targeting, expression duration, manufacturing feasibility, and immune profile. AAV’s advantages for the eye — stable expression in non-dividing photoreceptors, low immunogenicity in a relatively immune-privileged space — made it the vector of choice for retinal gene therapy.
Connection to inherited retinal disease
AAV serotype 2 was used in the first successful retinal gene therapy trials and in the approved product voretigene neparvovec. The vector carries a functional RPE65 gene to retinal pigment epithelium cells via subretinal injection. The development path from laboratory AAV to clinical-grade vector required advances in manufacturing, purification, quality control, and regulatory science.
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