virus packaging

How to titer retrovirus/lentivirus

A number of methods have been developed for determining the lentiviral/retroviral titers such as using ELISA to assess the amount of p24 antigen, enzyme assay to quantify reverse transcriptase activity, and real time RT-PCR to count viral RNA genome. However, these methods do not differentiate non-infectious from infectious virus particles that are present in the virus preparation; therefore, these measurements rely on some correlation factors to derive a titer, which can be inaccurate.

Because an accurate virus titer is critical for most experimental purposes, Allele Biotech’ pre-packaged viruses are measured by the number of genomic integration events to determine the infectious titer. This functional titering is done by first transducing TE671cells (selected for consistent transduction efficiency) followed by measuring the viral genome integrated into the cell genome with QPCR. The number of cellular genome copies is also measured, and the copy number of viruses is divided by that of cells to obtain active virus titer.
How to titer lentivirus retrovirus

A plot of quantitative PCR (Q-PCR) titering of virus preparation is provided above.
TE671 cells (1×105) were transduced with 2×10-3ml of a virus sample to be titered. Cells were harvested and DNA extracted for QPCR. The titer is determined as followed, transduction unit per ml (TU/ml)=N [X1/(X2/2)]/2×10-3ml, where N is the cell number, X1 is the copy number of integrated virus DNA, and X2 is the copy number of GAPDH DNA.

Take Advantage of Allele’s Essential Virus Grant Program, Have High Titer Virus for Your Research on Essential Human Genes

The number of Allele products in the form of viral particles is increasing quickly. Most of these products are also listed under product groups categorized according to their respective functions (e.g. iPS production under “Induced Pluripotent Stem Cells”, shRNA under “RNA Interference”, cytokines and enzymes under “Recombinant Proteins”). Additional background information, as well as related products, may be found on the landing pages of each product group.

The increase in scientific publications reporting the conversion of “dormant” genes into “active” ones has resulted in a significant demand for cDNA clones, antibodies, expression vectors, etc., all in short order. Providing reagents for the expansion of research on such genes is scientifically important and potentially rewarding if the market catches up. Allele Biotech works diligently to supply the most up-to-date and active researchers with pre-validated viral particles for expressing many of these “hot” genes, (e.g. iPS factors, light-activated ion channels, factors that induce neuronal cells from other cell types). Allele Biotech produces custom-packaged high titer lentivirus and retrovirus using unique technologies, as described under “Services by Category”-> “Viral Packaging”.
Under the Essential Virus Grant Program, Allele Biotech accepts custom viral packaging orders, including cDNA of shRNAs against recently established critical mammalian factors. The process begins with an evaluation of your one page application explaining why the factor can potentially be in demand by other researchers. If the application is accepted, Allele Biotech will waive the charges for the project and consider it an R&D effort. Allele Biotech will also offer it as a shelf product at a much lower cost than custom projects. Interested researchers please submit your applications with your order; our accounting department will promptly forward your request to our review group.

New Product of the Week 05-03-10 to 05-09-10: Essential Virus Grant Program

Promotion of the Week 05-03-10 to 05-09-10: for a limited time, pre-packaged, validated IL2 and IL15 lentiviruses.

Tags: , , , , ,

Wednesday, May 5th, 2010 Customer Feedback, Viruses and cells No Comments