Long-term expression and repeated administration of AAV type 1, 2 and 5 vectors in skeletal muscle of immunocompetent adult mice

Abstract

Adeno-associated viral (AAV) vectors promote long-term gene transfer into muscle in many animal species. Increased expression levels may be obtained by using alternative serotypes in combination with repeated administrations. Here we compared AAV vectors based on serotypes 1, 2 and 5 in immunocompetent mice and assessed the feasibility of multiple administrations of either identical (readministration) or different (cross-administration) serotype-based vectors. A 1-year-long dose-response study confirmed the superiority of recombinant (r)AAV1, achieving transduction levels 5 to 10-fold higher than rAAV2 and rAAV5 in mouse skeletal muscle, respectively. Repeated administration demonstrated that increased gene transfer level was achieved with a second injection of rAAV1 following the first administration of rAAV2 or rAAV5. A readministration study with a vector encoding a different gene allowed the evaluation of gene expression from the second vector only. All three rAAVs were inhibited when the animals were previously exposed to the same serotype. In contrast, no significant change in gene expression from the second vector was observed in cross-administration. A humoral immune response was elicited against the viral capsid for all three serotypes following the initial exposure. Neutralizing antibody (NAB) levels correlated with the vector dose injected. No significant cross-reactivity of NAB from a given serotype toward another was observed in vitro. These data provide the first direct comparative evaluation of re-and cross-administration of rAAV1, rAAV2 and rAAV5 in muscle, and further indicate that rAAV1 is capable of transducing muscle tissue when cross-administered.

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

“…The third approach is to randomly modify AAV capsids and to escape NAbs (2,36,37) and yield novel capsids with preferred tropism. The fourth approach is to use other types of AAV which have shown no or low NAb cross-reactivity in mice (27,30,38,60,65). To date, 12 types and several variants of AAV have been isolated and sequenced (15,16,22,23,47,50,61,65).…”

“…The prevalence of NAb in children is lower, ranging from 13 to 25% (9, 35). Although 11 additional types of AAV have been isolated for gene therapy purposes, little to no cross-reactivity of NAbs is demonstrated among these types in animals (27,30,38,60,65). In humans, recent studies have shown that different degrees of NAb cross-reactivity exist between AAV2 and other types (6,10,27,45).…”

“…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.…”

Immunity to adeno-associated virus vectors in animals and humans: a continued challenge

“…Numerous studies suggest that neutralizing capsid antibodies against one serotype have only limited cross-reactivity to other serotypes, thereby enabling sequential transduction of alternative serotypes. 5,71,72 Riviere et al 73 tested AAV vectors for their ability to escape capsid neutralization based on serotypes 1, 2 and 5 in immunocompetent mice and found that all three AAVs were inhibited by neutralizing antibodies upon secondary injections using the identical serotype. In contrast, gene expression was unaffected when alternative serotypes were used.…”

Efficient gene transfer in skeletal muscle with AAV-derived bicistronic vector using the FGF-1 IRES

“…14 Adeno-associated virus (AAV) derived vectors are highly effective for stable gene transfer in a number of tissues, including skeletal muscle, liver, retina and brain where long-lasting expression of therapeutic transgenes have been obtained in pre-clinical and human clinical studies. 19,20 AAV particles have a low packaging capacity and the size of sequences inserted into the vectors is strictly limited to less than 5 kb. 21,22 In this context, the use of short IRESs seems very attractive.…”