Subconjunctival vs. Intravitreal Administration for Gene Delivery and Expression of an Adenovirus Encoding Human Interferon Alpha–2b

Abstract

Abstract: : Purpose: To compare levels of adenovirus DNA and induced interferonalpha–2b protein (IFN) expression in ocular rabbit tissuesafter subconjunctival and intravitreal administration of adenovirusvector encoding human IFN (rAd–IFN).Methods: 9 NZW rabbits in three groups (3/group) were anesthetizedby intramuscular injection of ketamine and xylazine. 100ul ofrAd–IFN (8.4e10 particles) was delivered unilaterallyby subconjunctival injection (Group 1) and intravitreal injection(Group 2). Animals in the control group (Group 3) received a100ul subconjunctival injection of vehicle. 24h post injection,animals were euthanized and samples of conjunctiva, sclera,and choroid from the treated eyes and retina from both eyeswere dissected and frozen. The amount of rAd–IFN DNA wasdetermined by PCR. Human IFN protein content was determinedusing ELISA.Results: 

 

*t–test p<0.05 Minimal background signals for rAd–IFN DNA or IFN proteinwere detected in the control group. Neither rAd–IFN DNAnor IFN protein were detected in the contralateral eyes.Conclusions: Delivery of rAd–IFN DNA to the inside ofthe eye was substantially less efficient by subconjunctivalinjection than intravitreal injection, while delivery of IFNprotein was greater in the choroid and similar in the retinafollowing subconjunctival injection. Subconjunctival gene transfermay provide a less–invasive alternative to intravitrealgene transfer for protein delivery to the posterior segmentof the eye.

Keywords: adenovirus • gene transfer/gene therapy • choroid