Neutralizing antibody titer against AAV post AAV-mediated intravitreal injection in cynomolgus monkeys.

Abstract

Purpose : The adeno-associated virus (AAV) vector is an ideal tool for retinal gene therapy. Vitreal administration using a AAV vector has high safety without the retinal detachment. However, the transduction efficiency in the primates is extremely low. We already reported that surgical inner limiting membrane (ILM) peeling before intravitreal AAV administration acquired the strong transduction efficiency in cynomolgus monkeys. Recently, it was reported the intravitreal administration of AAV vector cause the increase of neutralizing antibody in the blood and vitreous. In this study, it was examined to compare neutralizing antibodies (NA) in the blood at pre/post AAV intravitreal administration. Moreover, we examined to whether the AAV mediated gene expression occurred in the trabecular meshwork (TM) that is responsible for draining ocular humor.

Methods : The six eyes in the three female cynomolgus monkeys were penetrated by 30-G needle into the vitreous and 50 μl of triple-mutated self-complementary AAV2 vector (1.9 × 10¹³ v.g./ml) encoding green fluorescent protein (GFP) was administered. NA in the serum was calculated at pre-administration, 2 weeks and 6weeks post administration. GFP expression was analyzed at 19 weeks post administration.

Results : Each NA titer is 1:10, 1:20, 1:20 (Geometric mean; 15.9) for pre-administration, 1:100, 1:300, 1:1000 (310.7) for 2 weeks post administration and 1:300, 1:1000, 1:1000 (669.4) for 6 weeks post administration. GFP expression in surgical ILM peeled retina detected, but GFP expression in TM did not detected in all eyes.

Conclusions : Up to now, it was thought that there was little influence to the whole body by intravitreal administration due to ocular immune privilege. However, once of intravitreal administration showed that NA value of a serum rises about 40 times. Interestingly, from the point of no GFP expression in TM, AAV vector might be recognized by immune system in the ocular tissue. The measurement of NA may offer a key to successful ocular gene therapy for AAV intravitreal injection.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.