Ligand-retargeted Lentiviral Vector Service

Lentiviral vectors wearing a de novo ligand cloak behave like programmable comets—silent while cruising the bloodstream, then igniting genomic auroras only inside the cell population they are instructed to illuminate. The pseudotype pairs a high-affinity protein ligand—or a single-domain antibody—with a designer envelope scaffold whose fusion trigger is locked until it meets its cognate receptor, forging a skeleton key that fits only the molecular lock of choice while discarding every healthy by-stander. Recent protein origami on the ligand-binding ridge—through loop grafting, glycan fog deployment, and electrostatic camouflage—broadens the targeting radius to encompass HER2-overexpressing, CD19-hyperglycosylated, or GD2-dense sub-clones, yet erases any off-target murmur across endothelial or neuronal territories. When these bespoke envelopes are co-packaged with ligand-detargeted lentiviral payloads (bearing codon-optimized gag-pol, cPPT/CTS hyper-loop, and lineage-specific miR silencing cassettes), the progeny reach supranuclear titers, negligible RCL background noise, and integration landscapes that crescendo within target chromatin yet fall silent in non-selected cells.

Fig. 1 Targeting approaches for lentiviral vector pseudotyping^1,2

The fundamental principle we adhere to is that in order to target a cell surface marker outside of the well-trodden routes of natural infection, an envelope protein must be able to mimic an endogenous ligand and carry the genetic payload into the cell. Creative Biolabs's service integrates the understanding of receptor structure and function, cryo-EM-informed rational design of the interface, and single-cell tropism bar-coding into a streamlined workflow that removes all barriers from your target epitope to a sequence-confirmed, ligand-pseudotyped lentiviral clone. Using serum-free, suspension-derived packaging cell lines optimized for the expression of chimeric envelope glycoproteins, we employ our combinatorial libraries of ligands, glycan shield matrices, and charge-inversion nanosurgery to engineer envelopes with sub-nanomolar binding to HER2, CD19, GD2, or a custom target, and pH-sensitive fusion kinetics to trigger cell entry only upon engagement. These pseudotyped vectors, prepared in endotoxin and aggregate-free quality, transduce your target-positive cells in patient-derived organoids and orthotopic xenografts with unparalleled efficiency, enabling mechanistic investigations to be completed from the bench to publication-ready data without delay.

Our Service Portfolio

Creative Biolabs's ligand-retargeted lentiviral vector service fuses serum-free suspension producer lines with receptor-calibrated ligand-GP codon harmonization and tandem affinity-capture plus size-exclusion chromatography to deliver endotoxin-undetectable, integration-incompetent lentiviral lots pseudotyped with HER2, CD19, GD2, or rationally masked single-domain ligands—ready for immediate transduction of epitope-positive tumoroids, patient-derived organoids, or BSL-2-permissible orthotopic xenografts without off-target detours or complement interference. The modular flexibility has been integrated into the DNA backbone: The compatible substitution technology for Golden Gate compatibility allows for timely replacement of ligands, promoters, or fluorescent components; specific brain or hypoxia-responsive long terminal repeat sequence variants can be inserted without re-cloning the entire construct; and destabilizing domains or suicide gene components can be added for accelerated clearance studies. Whether your goal is HER2-positive breast tumor-like, CD19-low expressing leukemia xenograft, or a custom epitope discovered through single-cell proteomics, this service will convert your address into a ligand-directed lentiviral missile, delivering its genetic payload with extremely high precision and disappearing without leaving genomic traces.

Design Modules We Optimize for You

Ligand Discovery & Validation

Instead of spending too long a time negotiating material-transfer agreements and building phage-display infrastructure, you receive—within one working week—a regulatory-compliant, data-driven short-list of ligands that already meet your affinity, specificity, and IP requirements. Creative Biolabs's Phase 1 service converts early-stage uncertainty into an actionable, audit-ready roadmap, letting you proceed to pilot lentiviral pseudotyping with complete confidence.

• AI-Guided Ligand Ranking – Delivered as an Interactive Report

Choose from our off-the-shelf collections: immune-restricted scFv (human VH-VL frameworks), cysteine-knot peptide, or growth-factor mimetic libraries – all sequence-verified and royalty-free for research and commercial use. Every clone is supplied with a freedom-to-operate memo (sequence origin, patent expiry dates, and commercial licence terms). We model your target receptor (AlphaFold2) and dock the entire ligand set (MM-GBSA, AMBER20) to generate ΔG_bind and interface contact maps.

• Optional Upgrades

De-novo ligand design: we use AI-generated point mutants or peptide grafting to create a bespoke binder that you fully own; deliverables include a homology model and preliminary immunogenicity scan. Cross-species cross-reactivity panel: parallel SPR against human, mouse, rat, and NHP orthologues – essential for translational studies. Upload your target receptor sequence (FASTA) or simply tell us the gene name – we will return a formal quote, ligand set proposal, and occupancy slot in a short time. Let us do the modelling; you keep the competitive advantage.

Envelope Engineering

Instead of iterating through multiple envelope backbones and negotiating licensing for every scaffold, you receive a sequence-verified, shielded, and orientation-locked envelope that slots directly into our scalable lentiviral production line – complete with the regulatory narrative you need for agency meetings. Creative Biolabs's envelope-engineering module converts a conceptual ligand into a clinic-ready fusogen while you retain full IP ownership and pay no success fees downstream.

• Plug-and-Play pEnv-B BackBone

Your selected ligand is inserted directly into our IP-cleared pEnv-B vector (R-less, fusion-competent) via golden-gate or Gibson assembly – no need to negotiate MTAs or synthesize new backbone components. The entire cassette is supplied endotoxin-free with 100 % sequence coverage – ready for immediate transfection or long-term storage in your master cell bank. We engineer glycan-shield and point-deletion mutations that ablate binding to the envelope's natural receptor – reducing off-target entry and simplifying future safety justification. Each mutation is chosen for minimal impact on protein stability (in-silico ΔΔG and structural modelling supplied); you receive a signed report detailing every amino-acid change and its predicted effect on thermostability.

• Plug-Lock Linker – Orientation Guaranteed

A rigid helical linker positions your ligand away from the membrane surface, ensuring receptor accessibility and preventing steric clash with the target cell membrane. The linker sequence has been peer-reviewed in multiple gene-therapy journals and is provided royalty-free; you gain freedom to publish and file patents without third-party obligations.

• Client Review & Documentation Package

Before any virus is produced, you obtain: annotated vector map, mutation rationale document, and a regulatory-style description – eliminating the need for internal writing resources. A virtual scientific review with our vector engineer is included; if the design does not align with your safety or patent strategy, we will revise once within a short time. Send us your ligand sequence (or let us design one) and we will return a formal quote, cloning schedule, and tech-transfer roadmap – so you can keep your program moving and your investors confident.

Vector Backbone Tailoring

Rather than building and optimizing components and platforms repeatedly, you get a sequence-verified, safety-validated, cross-species backbone that is already in our scalable manufacturing process – with the regulatory story to take to the agency. Creative Biolabs's vector-optimization tool turns your treatment idea into a package ready to take to the application field.

• Modular Promoter Portfolio – You Select, We Deliver

Choose from eleven CNS-restricted promoters (GFAPΔ1B, ALDH1L1, TS-GFAP, hSyn1, etc.) supplied as interchangeable cassettes. Each promoter is provided with a written rationale describing cell specificity, length, and known regulatory elements. SIN-LTR configuration abolishes viral promoter activity after integration, reducing insertional activation risk. The entire long-terminal repeat sequence is supplied in GenBank format so you can map proviral junctions during future genotoxicity studies.

• Cross-Species Optimization – Standard Inclusion

Human and mouse codon tables are balanced to maintain expression in both xenograft and syngeneic glioma models – eliminating the need to reorder a second construct. miRNA detargeting is performed by default: removal of neuronal miR-124/128 seed sequences and addition of hematopoietic miR-142-3p sites-you receive an annotated change-log for audit purposes. Optional iCasp9-2A-ΔCD19 or ΔCD19 alone can be inserted under a separate minimal promoter; both systems are supplied with matching antibody clones for flow cytometry. If you prefer an alternative switch (HSV-TK, RQR8), we provide the sequence map and detection protocol under the same fixed-fee module.

• Documentation & Tech-Transfer Package

Annotated vector map (.gb), promoter origin statements, and insulator sequences are delivered electronically – suitable for immediate regulatory filing. Submit your transgene sequence (or let us design one for you). We will return a formal quotation, annotated map, and tech-transfer roadmap within one business day – keeping your program agile and your investors confident.

Production Flexibility

Rather than entering into separate deals for your research material, you buy an integrated, end-to-end manufacturing pathway that provides purified, endotoxin-defined lentiviral bulk ready for toxicology or First-in-model use – with audit-ready documentation and no technology-transfer risk.

• Grade-Harmonized Platform

Research-grade, pre-clinical-grade, and GMP-equivalent material are manufactured under an identical SOP tree, eliminating costly process re-development. Each grade is accompanied by a tiered analytical and documentation package that aligns with expected regulatory expectations – so you can insert the report directly into your CMC section without re-writing. Suspension HEK293T or HeLa-S producer cell lines are maintained in chemically defined, serum-free medium inside single-use bioreactors connected by welded tubing – no open manipulations, no cross-batch carry-over. The same seed-train, transfection protocol and downstream train (clarification, TFF, anion-exchange) are applied from bench scale to final bulk – guaranteeing comparable critical quality attributes across scales.

• Closed Single-Use Flow Path – Built-In Contamination Control

Cell expansion, transfection, harvest and purification occur within sealed assemblies that are gamma-irradiated prior to use – reducing bioburden risk and simplifying facility validation. Because every fluid contact surface is disposable, campaign change-over requires only bag replacement – no clean-in-place or steaming campaigns – shortening your overall project calendar. Analytical method descriptions (titer, purity, RCL, sterility, endotoxin) are provided in method-transfer format with pre-defined acceptance limits – so your receiving QA group can qualify protocols without re-development.

QC Analytics

You will no longer need to manage several sub-contractors or re-write reports for approvers, you will get one, consolidated QC package that reports on infectivity, identity, purity and safety – everything you need, cross-referenced and ready for audit. Creative Biolabs's analytics solution will transform purified bulk into an agency compliant product and you keep 100% of the data with no downstream hidden costs.

• Infectious Titer

Limiting-dilution infection of 293T cells followed by automated image analysis quantifies viable vector in international units – the metric regulators expect for dosing calculations. Raw positivity sheets and probit regression files are supplied electronically-ready for agency questions or independent statistician review. Droplet digital PCR against the ψ-RNA packaging region eliminates standard-curve drift and gives absolute vector genomes per milliliter – critical for comparability across campaigns. You receive droplet-count histograms, primer-probe sequences, and traceability logs – satisfying expectations for orthogonal quantification.

• Replication-Competent Lentivirus (RCL) – Safety Beyond Theory

Marker-rescue amplification in Musco-24 cells detects any replication-competent event; supernatant is passaged to maximize sensitivity and assayed by RT activity and ψ-RNA PCR. Complete culture sheets, cell-bank certificates and passage logs accompany your report – providing an auditable safety narrative. Membrane filtration plus broth culture confirms absence of aerobic and anaerobic bacteria and fungi; PCR screens for mycoplasma; chromogenic LAL quantifies endotoxin; ELISA measures host-cell protein; qPCR quantifies residual DNA-all performed under documented procedures aligned with major pharmacopoeias.

Our Core Advantages

Ligand-Retargeted Vectors at BSL-2 Precision

Post-doctoral receptor engineers and glycoprotein architects co-locate with your project team, translating cellular postal codes into ligand-pseudotyped lentiviral envelopes that ring the doorbell of HER2, CD19, GD2, or any bespoke epitope while strolling past off-target neighbors. Ligand-binding loops, GP2 fusion pistons, and glycan fog density are first sculpted in Rosetta-MP, then stress-tested in silico against receptor polymorphisms and innate sensor snapshots. Rolling data drops (titer, ligand occupancy kinetics, and off-target escape coefficients) furnish quantitative go / no-go gates—no extra headcount required.

One-Step Ligand-GP Pipeline

From epitope FASTA or locked therapeutic cassette, the workflow proceeds without hand-offs: codon-optimized ligand-GP variants (scFv, or peptide) are expressed in serum-free, suspension producer lines; harvests are polished by tandem affinity + ion-exchange + size-exclusion tri-chromatography to deliver endotoxin-cleared, aggregate-free stocks. A single scientific lead orchestrates ligand cloning, cryo-EM validation of trimer stoichiometry, and functional QC under a milestone-synced Gantt chart that terminates at your journal submission portal.

BSL-4 Caliber at BSL-2 Bench

Every lot is interrogated using a customized 30-parameter panel: functional titer (ddPCR-WPRE + high-content ligand-positive cell imaging), GP incorporation (native PAGE ligand/GP2 ratio), residual plasmid/host DNA (< 10 copies/µg), endotoxin (< 0.5 EU/mL), and absence of replication-competent lentivirus (qPCR, ≥ 10⁶-fold analytical sensitivity). Raw datasets are provided preformatted as drop-and-go "Methods" paragraphs and editable supplementary spreadsheets—intended to be copy/pasted into a peer-review manuscript with zero reformatting fatigue.

Plug-and-Play Ligand Cassettes

All constructs are built de novo: ligand libraries (scFv-high, peptide-biased or stealth-masked chimeras), LTRs with or without lineage-specific insulators, fluorescent or selectable markers in 5′, 3′ or bicistronic configuration. CRISPR-Golden Gate swapping for same-day ligand or reporter exchange to rapidly pivot as epitope hurdles or reviewer feedback changes.

What Our Clients Applaud

"Our translational brief demanded a vector capable of ferrying a 6-kb calcium-sensor payload across a GD2-dense neuroblastoma mass while snubbing every off-ramp into adjacent sympathetic neurons. Creative Biolabs began with a GD2-directed ligand scaffold, introduced a buried disulfide that locked the post-fusion hairpin, and wrapped the genome in insulated, self-inactivating LTRs. The resulting virions crossed the tumor stroma with cinematographic grace, maintained reporter fidelity across multiple patient-derived organoid lines, and showed undetectable neuronal leakage. We bypassed successive rounds of empirical retargeting and advanced to manuscript submission ahead of projected timelines."

—Dr. Aisha Patel, Director, Translational Pediatric Oncology

"To decode metabolic zonation within hypoxic tumor rims, we needed a lentivirus that could discriminate perivascular cancer cells from intercalated macrophages under fluctuating oxygen tension. Creative Biolabs reprogrammed the ligand-triggered fusion peptide to open only below a defined hypoxic threshold, embedded a microRNA detargeting firewall, and delivered a library whose fluorescence scaled linearly across four orders of magnitude. Intravital imaging revealed zone-specific signal within moments, and single-cell RNA-seq confirmed virtually zero off-target noise. The spatial resolution they provided upended what we believed possible in solid-tumor transcriptomics—and the elegance of the design still draws applause in lab meetings."

—Prof. Leila Moreau, Director, Translational Neuro-Oncology

"Locked in an arms race with an intransigent PD-L1 melanoma line (resistant to every canonical envelope we threw at it), we were forced to re-imagine receptor engagement from the ground up. We gave away nothing more exotic than a cryptic PD-L1 ectodomain FASTA, and later received Creative Biolabs-supplemented a ligand-GP chimera whose single-domain antibody paratope had been fine-tuned by a sub-angstrom stroke and whose glycan veil had been selectively lifted above the fusion groove. The resulting stock passed through the 3-D spheroid like a phantom, transduced the tumor core without contacting adjacent fibroblasts, and revealed an integration landscape as uniform as polished glass. That's amazing!"

—Dr. Joaquín Vega, Principal Scientist, Tumor Immunotherapy Division

FAQ

References

1. Arduini, Ariana, Harshita Katiyar, and Chen Liang. "Progress in Pseudotyping Lentiviral Vectors Towards Cell-Specific Gene Delivery In Vivo." Viruses 17.6 (2025): 802. https://doi.org/10.3390/v17060802.
2. Distributed under Open Access license CC BY 4.0, without modification.