FAQ

Yes. We offer piVector Designer, an online-tool to help you design the lentivirus plasmid. The plamid backbones of various application we provided in piVector Designer is experimentally validated by us, and we provide a vast library of gene elements including promoter, reporter/marker, regulatory elements and polyA. Also, our Ph.D. level techincal support team will evaluate

Customers only need to send us 10μg of plasmid for lentivirus production. We will amplify and QC the plasmid before use, with the plasmid prep cost and timeline included in the service fee. Typically, research-grade lentivirus requires 300ug for 5E7, 600ug for 1E8, while preclinical-grade lentivirus requires 1.5mg for 5E7, and 3mg for 1E8.

All equipment or tips in contact with lentivirus or virus-infected cells should be immersed in a 10% bleach solution for 20 minutes before disposal in biohazardous waste.

We use either 293T adherent cells or PCS01 suspension cells (a single-clone suspension cell line originated from HEK293 cells).

We utilize Opti-Medium as the buffer at a concentration of 50μl/mL for lentivirus storage.

Viral titers are typically reported in two forms: functional titer(infectious titer), expressed as transduction units (TU/mL), and physical titer, measured in viral particles (VP/mL). The physical titer indicates the total amount of virus present, often quantified by assessing levels of viral proteins like p24 or viral nucleic acids. In contrast, the functional titer(infectious titer) reflects the virus’s ability to infect cells and is usually 100 to 1000 times lower than the physical titer. Although direct measurement of functional titer(infectious titer) is more accurate for calculating the multiplicity of infection (MOI), it is often more labor-intensive. At PackGene, lentivirus scale is based on post-transduction titer, providing infectious titers that are significantly higher than the physical titer measured by p24, ensuring greater accuracy for experimental applications.

Since the transduction unit is determined after storage, we do not adjust the concentration to avoid additional freeze-thaw cycles that may significantly lower the titer. Customers can adjust the concentration as needed upon infection.

In contrast to the common practice among most vendors, who typically measure lentivirus titer directly using methods such as qPCR or p24 ELISA. The Traditional p24 ELISA kit is the most commonly published method for measuring lentiviral titer. The method is suitable for tittering native or purified recombinant virus. However, in crude (unpurified) lentiviral supernatant, significant concentrations of overexpressed p24 protein may be present that are not assembled into viral particles. This causes an extreme overestimation of lentiviral titer.

We employ a different approach. Our titer measurement focuses on the post-transduction titer determined by qPCR, which helps to eliminate any concerns regarding overestimation, providing infectious titers that are significantly higher (100-1000 times) than the physical titer measured by p24, ensuring greater accuracy and consistency for experimental applications.

Additionally, if the lentivirus carries a fluorescent protein, we can further validate the post-transduction titer by examining bright-field and fluorescent microscopy images obtained from serial dilutions of the virus.