Biology subjects

Hirsch, M. L.

Publications and source records attributed to Hirsch, M. L..

3 recordsLinked to original sources

bioRxiv2026

Adeno-Associated Virus (AAV) Synthetic Inverted Terminal Repeats Enhance Tissue-Specific Transduction and Alter the Vector Induced Stress Response

While adeno-associated virus (AAV) vectors have shown therapeutic benefit in clinical applications, noted challenges include low transduction efficiencies, poor cellular targeting, and vector related adverse events. Recently, it was demonstrated that a rationally designed synthetic inverted terminal repeat (SynITR) altered the AAV vector-induced DNA damage response and abrogated apoptosis in human embryonic stem cells. To explore the utility of AAV-SynITR for diverse gene therapy applications, vector production, transduction, and the cellular response were evaluated in various contexts. Regarding production, SynITR preparations exhibited comparable titers to wtITR in a serotype/transgene-independent manner. Despite slightly decreased transduction efficiency in various cell lines, intravenous administration of AAV8 vectors showed SynITR enhanced transduction in a tissue-specific manner in liver (>7-fold) and kidney and pancreas (>2-fold) at equivalent vector copy numbers; however, no differences were observed in muscle/heart/spleen tissues. Interestingly, persistent {gamma}H2AX, a marker of aging/chronic inflammation, was abundant in the liver and spleen following wtITR (but not SynITR) transduction. In human corneas, SynITR enhanced transduction up to 16-fold over wtITRs. These data demonstrate that SynITRs elicit tissue-specific transduction enhancement and alter the cellular stress response. Importantly, the SynITRs offer an alternative context to elucidate wtITR biology for targeted, enhanced, and potentially safer human gene therapy.

molecular biology↗

bioRxiv2022

AAV Vector Transduction Restriction and Attenuated Toxicity in hESCs via a Rationally Designed Inverted Terminal Repeat

Recombinant adeno-associated virus (rAAV) inverted terminal repeats (ITRs) induce p53-dependent apoptosis in human embryonic stem cells (hESCs). To interrogate this phenomenon, a rationally designed ITR (SynITR), deleted for p53 binding sites was evaluated for vector production and gene delivery. While SynITR genomes were decreased for transgenic genome replication compared to wtITRs, similar production titers indicated that replication is not rate-limiting. Packaged in the AAV2 capsid, wtITR and SynITR vectors demonstrated similar transduction efficiencies of human cell lines with no differences in reporter kinetics. Following rAAV2-wtITR infection of hESCs, rapid apoptosis was observed, in contrast, rAAV2-SynITR infection resulted in attenuated hESC toxicity with cells retaining their differentiation potential. While hESC particle entry and double stranded circular episomes was similar for the ITR contexts, reporter expression was significantly inhibited from transduced SynITR genomes. Infection of hESCs induced {gamma}H2AX in an ITR-independent manner, however, canonical activation of p53 was uncoupled using rAAV-SynITR. Further hESC investigations revealed 2 additional novel findings: i) p53{beta} is uniquely and constitutively active, and ii) rAAV infection, independent of the ITR sequence, induces activation of p53{psi}. The data herein reveal an ITR-dependent rAAV transduction restriction specific to hESCs and manipulation of the DNA damage response via ITR engineering.

molecular biology↗

bioRxiv2020

Wild type AAV, recombinant AAV, and Adenovirus super infection impact on AAV vector mobilization

Recombinant Adeno-associated viral vector (rAAV) mobilization is a largely theoretical process in which intact AAV vectors spread or "mobilize" from transduced cells and infect additional cells within, or external, of the initial host. This process can be replication independent (vector alone), or replication-dependent (de novo rAAV production facilitated by super-infection of both wild-type AAV (wtAAV) and Ad helper virus). Herein, rAAV production and mobilization with and without wtAAV were analyzed following plasmid transfection or viral transduction utilizing well established in vitro conditions and analytical measurements. During in vitro production, wtAAV produced the highest titer with rAAV-luc (4.1 Kb), rAAV-IDUA (3.7 Kb), and rAAV-NanoDysferlin (4.9 Kb) generating 2.5-, 5.9-, or 10.7-fold lower amounts, respectively. Surprisingly, cotransfection of a wtAAV and a rAAV plasmid resulted in a uniform decrease in production of wtAAV in all instances with a concomitant increase of rAAV such that wtAAV:rAAV titers were at a ratio of 1:1 for all constructs investigated. These results were shown to be independent of the rAAV transgenic sequence, size, transgene, or promoter choice and point to novel aspects of wtAAV complementation that enhance current vector production systems yet to be de fined. In a mobilization assay, a sizeable amount of rAAV recovered from infected 293 cell lysate remained intact and competent for a secondary round of infection (termed non-replicative mobilization). In rAAV infected cells co-infected with Ad5 and wtAAV, rAAV particle production was increased > 50-fold compared to non-replicative conditions. In addition, replicative dependent rAAV vectors mobilized and resulted in >1,000 -fold transduction upon a subsequent 2nd round infection, highlighting the reality of these theoretical safety concerns that can be manifested under various conditions. Overall, these studies document and signify the need for mobilization resistant vectors and the opportunity to derive better vector production systems.

microbiology↗