{
  "abstract": "Adeno-associated virus (AAV) vectors are widely used for gene delivery to the central nervous system, but natural capsid tropism is broad and cell-type restriction is typically imposed transcriptionally using promoters and enhancers that consume packaging capacity and often drive weak expression. Here, we engineer neuronal targeting directly into the AAV-DJ capsid by ablating its endogenous heparan sulfate proteoglycan (HSPG) affinity and genetically displaying a nanobody against the Group 1 metabotropic glutamate receptor mGluR5 within the VP1 subunit at a permissive capsid loop (T456), generating AAV-m5. Western blot confirmed incorporation of the nanobody-VP1 fusion into assembled capsids. In primary hippocampal neuron cultures, ablating HSPG binding abolished infectivity and nanobody display rescued transduction while restricting GFP expression almost exclusively to mGluR5-positive neurons. Heparin competition assays showed that, unlike wild-type AAV-DJ, AAV-m5 transduction was unaffected by exogenous heparin, confirming that entry occurs independently of HSPG binding. Packaged with a strong constitutive promoter (CAG), AAV-m5 achieved neuron-restricted expression comparable to or exceeding that of wild-type AAV-DJ driven by a neuron-specific promoter (hSyn) and produced negligible expression under an astrocyte-specific promoter (GFAP) despite promoter activity in glia, demonstrating that capsid-level targeting can substitute, or complement, transcriptional restriction. Following stereotactic injection into the mouse hippocampus, AAV-m5 achieved an eight-fold higher proportion of transduced neurons than wild-type AAV-DJ at equivalent titers. Delivery to Grm5-null hippocampus reduced both the intensity and the spatial extent of transduction, confirming that the broad hippocampal transduction achieved by AAV-m5 is mGluR5-dependent. Together, these results establish nanobody-functionalized AAV-DJ as a modular, single-component platform for precision CNS gene delivery that circumvents the packaging and expression trade-offs of promoter-based cell-type restriction, with potential for retargeting to additional CNS cell types and disease-relevant receptors.",
  "abstract_shown": true,
  "affiliations": [
    "University of Minnesota"
  ],
  "article_type": "New results",
  "arxiv": null,
  "author_total": 5,
  "authors": [
    {
      "name": "A. Extross"
    },
    {
      "name": "E. M. Fernandez de Velasco"
    },
    {
      "name": "Y. He"
    },
    {
      "name": "K. Wickman"
    },
    {
      "affs": [
        0
      ],
      "name": "D. Schmidt"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/5x7cw82mxzc0h.bib",
  "cited_by": 0,
  "doi": "10.64898/2026.09.18.752817",
  "fulltext_url": "https://www.biorxiv.org/content/10.64898/2026.09.18.752817v1.full",
  "id": "5x7cw82mxzc0h",
  "issns": [],
  "landing_url": "https://www.biorxiv.org/content/10.64898/2026.09.18.752817v1",
  "language": null,
  "licence": "CC-BY",
  "licence_label": "CC BY",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "biorxiv",
      "synthetic biology"
    ],
    [
      "openalex",
      "1311|Virus-based gene therapy research"
    ]
  ],
  "openalex": "W7214018288",
  "pdf_url": "https://www.biorxiv.org/content/10.64898/2026.09.18.752817v1.full.pdf",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-18",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/5x7cw82mxzc0h.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:23:47Z",
      "native_id": "10.64898/2026.09.18.752817",
      "source": "biorxiv",
      "url": "https://www.biorxiv.org/content/10.64898/2026.09.18.752817v1"
    }
  ],
  "subjects": [
    {
      "field": "biology",
      "origin": "biorxiv:synthetic biology",
      "subfield": "systems-synthetic"
    }
  ],
  "title": "Nanobody-Functionalized AAV achieves Promoter-independent Neuronal Targeting in the CNS",
  "title_text": "Nanobody-Functionalized AAV achieves Promoter-independent Neuronal Targeting in the CNS",
  "type": "preprint",
  "updated_at": "2026-10-30T12:23:47Z",
  "url": "https://research.draconitic.com/paper/5x7cw82mxzc0h",
  "venue": "bioRxiv",
  "versions": []
}