Neutralizing Antibodies Against AAV Serotypes 1, 2, 6, and 9 in Sera of Commonly Used Animal Models

Abstract

Adeno-associated virus (AAV)-based vectors are promising gene delivery vehicles for human gene transfer. One significant obstacle to AAV-based gene therapy is the high prevalence of neutralizing antibodies in humans. Until now, it was thought that, except for nonhuman primates, pre-existing neutralizing antibodies are not a problem in small or large animal models for gene therapy. Here, we demonstrate that sera of several animal models of cardiovascular diseases harbor pre-existing antibodies against the cardiotropic AAV serotypes AAV1, AAV6, and AAV9 and against AAV2. The neutralizing antibody titers vary widely both between species and between serotypes. Of all species tested, rats displayed the lowest levels of neutralizing antibodies. Surprisingly, naive mice obtained directly from commercial vendors harbored neutralizing antibodies. Of the large animal models tested, the neutralization of AAV6 transduction by dog sera was especially pronounced. Sera of sheep and rabbits showed modest neutralization of AAV transduction whereas porcine sera strongly inhibited transduction by all AAV serotypes and displayed the largest variation between individual animals. Importantly, neutralizing antibody titers as low as 1/4 completely prevented in vivo transduction by AAV9 in rats. Our results suggest that prescreening of animals for neutralizing antibodies will be important for future gene transfer experiments in these animal models.

Primary Effect of SERCA2a Gene Transfer on Conduction Reserve in Chronic Myocardial Infarction

“…All pigs were subjected to extensive anterior MI (procedure described below) and cage‐housed for 1 month to develop chronic HF with marked left ventricular (LV) dysfunction compared with control pigs as we have previous reported 8. Animal sera were collected at the time of MI to screen for neutralizing antibodies against AAV1 9. Only animals with neutralizing antibody titer of <1/2 qualified for AAV1.SERCA2a treatment.…”

Adaptive Immune Responses Elicited by Baculovirus and Impacts on Subsequent Transgene Expression In Vivo

“…As the control, HeLa cells were transduced with Bac-CE, and the total fluorescence was measured. The neutralizing titer was defined as the dilution at which transduction was inhibited by Ͼ50% compared to transduction controls in the absence of serum (32). For gp64 antagonization, gp64 was first purified as described previously (33).…”

Cardiac gene therapy in large animals: bridge from bench to bedside

“…The relatively high prevalence of neutralizing antibodies for adeno-associated virus in large animals has been reported. 96 Therefore, prescreening of animals is required prior to enrolling them in gene transfer studies.…”