MMLV Retrovirus Packaging

Recombinant Moloney murine leukemia virus (MMLV) retroviral vectors serve as efficient viral vector tools for introducing genes permanently into a wide variety of dividing cells. This retroviral system came into prominence as a gene delivery method for generating iPS cells.
VectorBuilder has developed a series of proprietary technologies and reagents that have greatly improved recombinant MMLV retrovirus production protocols in terms of titer, purity, viability and consistency, especially for the MMLV vector systems used in our vector cloning services. As a result, we have a growing base of highly satisfied customers who come back to us time after time for their MMLV vector cloning and MMLV packaging needs.
Click here to read detailed introduction of our MMLV vector systems
Click here to view citations of our MMLV
Click here to view user testimonials of our MMLV
How do I obtain MMLV retrovirus packaging services?

Click here to view an example of a finished MMLV vector design
Click here to view an example of an MMLV service proposal
Click here to view instructions on designing a vector on VectorBuilder
Click here to view instructions on placing an order on VectorBuilder
Types of MMLV retrovirus offered

We offer packaging services for VSV-G pseudotyped MMLV retrovirus.

Price and turnaround

Due to our technological advantage, our recombinant MMLV retrovirus services have the highest quality in the industry and are also faster and more affordable than those from other suppliers. Prices and turnaround times for different scales of MMLV packaging are shown below:

Scale Application Titer & Volume* Price (USD) Turnaround**
Pilot Cell culture >107 TU/ml, 10x25 ul, HBSS buffer $399 8-16 days
Medium Cell culture >107 TU/ml, 10x100 ul, HBSS buffer $599 8-16 days
Large Cell culture >108 TU/ml, 10x100 ul, HBSS buffer $999 8-16 days
Ultra-purified large Cell culture & in vivo >108 TU/ml, 10x100 ul, HBSS buffer $1499 8-16 days

TU = Transduction unit (aka infectious unit)

* Our titer guarantee only applies to vectors for which the region being packaged into virus (from 5’ MoMuLV LTR to 3’ MoMuLV LTR) is below MMLV cargo limit (8 kb). For sizes above this, it may still be possible to package the vector into virus, but the titer may be reduced. Additionally, we are not able to guarantee titer for the following vectors:

  • vectors containing sequences that could adversely affect the packaging process such as toxic genes (e.g. proapoptotic genes), genes that compromise the integrity of packaging cells or virus (e.g. membrane proteins that cause cell aggregation), and sequences prone to rearrangements or secondary structures (e.g. repetitive or highly GC-rich sequences);
  • customer-supplied plasmids containing undisclosed sequences or atypical MMLV functional elements (e.g. LTR) that may introduce uncertainties to packaging efficiency.

** Estimated turnaround is the time from production initiation to completion. It does not include waiting time for any customer-supplied materials (e.g. template DNA or viral vectors), QC of such materials, and transit time for shipping final deliverables to the customer.


If you choose pilot, medium or large scale MMLV packaging, each order includes the following deliverables:

  • Aliquots of custom MMLV at selected scale
  • Free: aliquots of control virus*
  • Free: Polybrene (5 mg/ml, 200 ul)

If you choose ultra-purified large scale MMLV packaging (in vivo grade), each order includes the following deliverables:

  • Aliquots of custom MMLV at selected scale
  • "Add-on" purchase (optional): aliquots of ultra-purified control virus*
  • Free: Polybrene (5 mg/ml, 200 ul)
* The control retrovirus vector is designed to match the biological application of the custom virus and to be used for testing retroviral transduction. For example, if the custom virus overexpresses a gene, then the control virus provided will be EGFP control retrovirus (MMLV retrovirus overexpressing EGFP). Detailed information for the various control viruses is shown below:
Vector System Control Vector Name Control Vector ID Custom Virus Packaging Scale Control Virus Amount Price (USD)
MMLV gene expression system pMMLV[Exp]-EGFP/Puro VB170316-1032yra Pilot >107 TU/ml, 100 ul in HBSS Free
Medium >107 TU/ml, 2x100 ul in HBSS Free
Large >107 TU/ml, 2x100 ul in HBSS Free
Ultra-purified large >108 TU/ml, 10x100 ul in HBSS $500
Production, purification and titration

For our MMLV retrovirus manufacturing, the transfer vector carrying the gene of interest (GOI) is co-transfected into packaging cells with our proprietary envelope vector encoding VSV-G and our packaging vector encoding Gag and Pol. After a short incubation period, the supernatant is collected and centrifuged to remove cell debris and then filtered. Viral particles are subsequently concentrated with PEG. For ultra-purified MMLV retrovirus (in vivo grade), viral particles are further purified and concentrated by sucrose cushion centrifugation. We use a qPCR-based approach to measure the functional titer of MMLV.

Quality control

For each recombinant MMLV retrovirus produced by VectorBuilder, quality control includes titer measurement, sterility testing for bacteria and fungi, and mycoplasma detection. If the transfer vector encodes a fluorescent protein, we would transduce cells with virus and detect corresponding fluorescence. Additionally, for ultra-purified MMLV, we routinely sample virus quality using the endotoxin assay.

Customer-supplied vectors

If customer-supplied MMLV retroviral plasmids are needed, please send them to us following the Materials Submission Guidelines. Please strictly follow our guidelines to set up shipment to avoid any delay or damage of materials. All customer-supplied materials undergo mandatory QC by VectorBuilder which may incur a $100 surcharge for each item. Please note that production may not be initiated until customer-supplied materials pass QC.


Please refer to our Vector FAQ for commonly asked technical questions. To get additional information about what we can offer, please contact VectorBuilder's service team following the contact information here.