LV-EF1a-tdTOMATO

What it means: EF1a is the human elongation factor 1 alpha promoter, a strong constitutive cellular promoter that resists silencing and gives stable long-term expression in a wide range of cell types, including stem cells and primary cells.

Why it matters:

• The promoter sets where and how strongly the cassette is expressed after transduction.
• EF1a is generally preferred over viral promoters when sustained expression is needed.
• Promoter choice also affects how quickly expression appears and whether it persists after weeks in culture or in vivo.

How to interpret here: in LV-EF1a-tdTOMATO, EF1a drives tdTomato, so expect the expression pattern described above in transduced cells.

Tip: when comparing constructs, keep the promoter constant — differences between EF1a and another promoter can be larger than the effect of the transgene itself.

What it means: tdTomato is a fluorescent protein reporter; transduced cells can be identified by fluorescence microscopy or flow cytometry.

Why it matters:

• tdTomato lets you confirm transduction and enrich or track positive cells without antibody staining.
• Choose imaging filters or flow cytometry lasers that match tdTomato, and keep reporter channels separate from other labels in the experiment.
• Reporter expression is also a convenient proxy for titrating MOI on a new cell type before running the actual experiment.

How to interpret here: cells transduced with this vector will express tdTomato; dim and bright populations usually reflect integrated copy number rather than failed transduction.

Tip: include non-transduced cells as the gating or exposure control so autofluorescence is not mistaken for tdTomato signal.

What it means: Constitutive — expression is continuous and not dependent on an inducer or recombinase.

Why it matters:

• No additional reagent or driver line is needed; expression begins after integration and continues in daughter cells.
• No inducer, recombinase, driver line or partner construct is needed, which keeps the experiment simple.
• The trade-off is that expression cannot be switched off or timed, so it continues from integration onward in every transduced cell.

How to interpret here: LV-EF1a-tdTOMATO expresses its cassette continuously from the EF1a promoter as soon as it has integrated.

Tip: compare against a control vector with the same backbone, promoter and selection marker rather than against untransduced cells, so transduction and selection effects can be separated from the cassette effect; ask us if a matching control is not listed.

What it means: None — no antibiotic resistance gene is included.

Why it matters:

• Without a resistance gene there is no drug step, so no stable pool can be enriched by selection; identify transduced cells by the tdTomato reporter, by FACS or by a functional readout.
• Leaving the marker out keeps the cassette smaller and avoids occupying a resistance gene that another construct in the same cells may need.
• It also means the transduced and untransduced fractions stay mixed unless they are physically sorted.

How to interpret here: the selection marker for this vector is None.

Tip: sort on the reporter to obtain a uniform population, and record the transduced fraction so downstream results can be corrected for it.

What it means: >1E+9 TU/mL is the functional titer in transducing units (TU) per mL — the number of particles that actually deliver and express the cassette, not the physical particle count.

Why it matters:

• Functional titer is what determines the multiplicity of infection (MOI) you can reach with a given volume.
• The value is stated as a minimum (>1E+9 TU/mL), so treat it as a floor when planning volumes rather than as an exact content figure.
• Functional titers are assay-dependent, so compare titers between vendors only when the titration method is the same.

How to interpret here: calculate MOI from >1E+9 TU/mL and your cell number; optimize MOI per cell type, since transduction efficiency differs between lines and primary cells.

Tip: keep the vector cold during dilution and avoid vortexing — titer loss from repeated freeze-thaw or rough handling is the most common reason a >1E+9 TU/mL stock underperforms.

What it means: BSL-2 is the biosafety containment level required for handling this lentiviral vector.

Why it matters:

• BSL-2 work requires a certified biosafety cabinet, appropriate PPE and decontamination of all waste and surfaces.
• Institutional biosafety approval is usually required before lentiviral work begins, and transfer between labs follows the same containment rules.
• Transduced cells and used media remain BSL-2 material until decontaminated.

How to interpret here: handle LV-EF1a-tdTOMATO under BSL-2 practices throughout storage, thawing, transduction and disposal.

Tip: check whether your institution requires enhanced BSL-2 practices for lentiviral vectors carrying particular transgenes; this varies between institutions.