PEG conjugation moderately protects adeno-associated viral vectors against antibody neutralization

Abstract

AAV gene therapy vectors have significant clinical promise, but serum neutralization poses a challenge that must be overcome. We have examined the potential of conjugating the AAV surface with activated polyethylene glycol chains to protect the vector from neutralizing antibodies. Two key parameters were investigated: the polymer chain size and the PEG:lysine conjugation ratio. Transduction data revealed that the vector is fully infectious until a critical PEG conjugation reaction ratio was exceeded, and this critical level was found to vary with polymer chain size. At this key conjugation ratio, however, particles were moderately protected from serum neutralization, 2.3-fold over unmodified vector, demonstrating that there is a small window of PEGylation for which particles are still fully infective and benefit from antibody protection. TEM results and structural analysis indicate that the drop of infectivity as the PEG concentration is increased beyond the critical conjugation ratio may be due to a combination of steric interference with viral regions necessary for infection as well as reaction at important lysine residues. However, this first study analyzing the potential of PEG to protect AAV from serum neutralization shows that the approach has promise, which can be further enhanced if the locations of PEG attachment can be more finely controlled. ß

Single Amino Acid Modification of Adeno-Associated Virus Capsid Changes Transduction and Humoral Immune Profiles

“…To overcome AAV NAb inhibition of AAV vector transduction, several approaches have been exploited in the lab. One of them is to use a polymer to cover the AAV surface and block NAb recognition (11,32,33). The second approach is to use error-prone PCR to generate a library of AAV variants and select for NAb escape mutants in the presence of NAb in vitro (31,41,56).…”

“…These findings present a concern to the gene therapy community as to how we can avoid antagonistic NAb activity during systemic delivery of AAV vectors. To overcome this concern, several approaches have been exploited in our lab and by other groups, including (i) the utilization of polymers to cover the AAV capsid and block NAb recognition (11,32,33), (ii) the development of NAb escape mutants by error-prone PCR in vitro (31,41,56), (iii) the application of other types of AAV vectors (27,30,38,60,65), and (iv) the generation of chimeric types via AAV shuffling (2,36,37). In this study, we have systematically explored the possibility of using different types and AAV mutants as alternative vectors for intramuscular gene delivery in mice preimmunized against different AAV types.…”

Pegilasyon: PEG konjugatlarının hazırlanması ve uygulamaları

“…Pegilasyon işlemi sonucu elde edilen konjugatlar aşağıda belirtilen özellikleri göstermektedir(Şekil 4) [2,7,[8][9][10][11][12][13][14][15]]. …”

Protection of adenovirus from neutralizing antibody by cationic PEG derivative ionically linked to adenovirus

“…[15][16][17][18][19] However, studies have shown that chemical conjugation reduced infection activity of Adv, associated with steric hindrance from flexible polyethylene glycol (PEG) chains, resulting in a decreased gene transduction and transgenic expression. 16,20,21 This can be partially compensated for by a targeted ligand covalently conjugated to the PEG (ligand-PEG-Adv). 22,23 Moreover, chemical conjugation showed protection of Adv in a titer-related way, but still failed in complete avoidance of the immune response or a negligible influence by NAb.…”