An Adenovirus Vector with Genetically Modified Fibers Demonstrates Expanded Tropism via Utilization of a Coxsackievirus and Adenovirus Receptor-Independent Cell Entry Mechanism

TLDR

Recombinant adenoviruses are widely used gene therapy vectors, yet their efficiency is limited in cells with low coxsackievirus and adenovirus receptor (CAR) expression. The authors sought to enable CAR‑independent gene transfer by altering the adenovirus fiber protein. They engineered the fiber knob’s HI loop to display an Arg‑Gly‑Asp (RGD) peptide, thereby redirecting viral entry to an alternative receptor. The RGD‑modified vector achieved 2–3 orders of magnitude higher transduction of ovarian cancer cells and efficiently transduced primary tumor cells, demonstrating expanded tissue tropism and potential therapeutic value for CAR‑deficient neoplasms.

Abstract

ABSTRACT Recombinant adenoviruses (Ad) have become the vector system of choice for a variety of gene therapy applications. However, the utility of Ad vectors is limited due to the low efficiency of Ad-mediated gene transfer to cells expressing marginal levels of the coxsackievirus and adenovirus receptor (CAR). In order to achieve CAR-independent gene transfer by Ad vectors in clinically important contexts, we proposed modification of viral tropism via genetic alterations to the viral fiber protein. We have shown that incorporation of an Arg-Gly-Asp (RGD)-containing peptide in the HI loop of the fiber knob domain results in the ability of the virus to utilize an alternative receptor during the cell entry process. We have also demonstrated that due to its expanded tissue tropism, this novel vector is capable of efficient transduction of primary tumor cells. An increase in gene transfer to ovarian cancer cells of 2 to 3 orders of magnitude was demonstrated by the vector, suggesting that recombinant Ad containing fibers with an incorporated RGD peptide may be of great utility for treatment of neoplasms characterized by deficiency of the primary Ad type 5 receptor.