GPCR: problems and resolutions in high content screening, Part II

2) Without a mark (continued from Part I by Niels Yuhui Ni, MD Ph.D. of Allele Biotech)

In this section, the author focused on the “Label-Free” system. “A newer alternative that has given hope” because these systems are closer to the real cellular conditions most GPCR studies are meant to address. However, label-free systems must depend on complicated detection system for high content analysis. As commented, “For some scientist though, this technology is simply still too new and for now, too expensive for many categorical assessments…” While I am a believer in label-free detection, however, here is my question, for this group of scientists, are there any good alternatives now, before the label-free systems become more accessible? Using the traditional over-expression cell lines seems less and less attractive (see Part I under the same blog topic here)? A system that combines immortalized primary cells and a non-integrated expression system could be a nice system that does not require high end equipment or heavy commitment in technology development especially if the components were commercially available. The third, critical component of this system could be the application of newer, brighter and monomeric and thus less toxic fluorescent proteins or FRET pairs as sensors. Obviously part of the reason that I thought about such a system was because our research team at Allele Biotech has the background in all 3 components, whereas others might have their own preferred methods. To me, it seems that immortalized primary cells present a renewable cell source, and for non-integration delivery, we prefer Baculo viral delivery vehicles for mammalian infection (called BacMam by some). Both platforms are being offered as products or services already or in the pipeline teed up for launching.

Baculo2Mam non-intergrated viral delivery system:
Many people may know about Baculovirus such as in the Bac-to-Bac system from Invotrogen or the Sapphire baculovirus system from Orbigen (acquired by Allele Biotech). But how many of us know that even though mammalian cells are not the nature host of baculovirus, they still can be infected with modest modifications on the virus. Both the safety and efficiency of Baculovirus for mammalian use are superb. Based on the data from our customers’ projects, most protein expression require baculoviral protein expression in insect cells, only about 10% require Baculo2Mam. We actually feel a sense of responsibility for introducing this technology to as many as researchers as possible.

The following list shows some of the advantages of Baculo2Mam I can list right now, for more details check back on our blog articles in coming days or contact us at any time for discussion.
1) Baculoviruses are Risk Group 1 or biosafety 1 agents.
They are produced in insect cells and can not replicate in mammalian cells. They express genes in human or mouse cells in non-integrated state for about 2 weeks (varies in different cells).
2) Baculoviruses can be easily generated in high titer and production rapidly scaled-up.
That is when compared with other viral systems. For example, baculovirus is a budding virus that is released into cell medium, unlike adenovirus that requires lysing cells during productions. Allele Biotech now provides Baculo2Mam viral packaging service at an affordable price for routine use. Your viral clones can be stored in Allele Biotech’s Baculo2Mam virus bank; if you need the virus again, you can just order a production service at an even lower price.
3) Broad host cell range including many primary cells.
Many terminally differentiated primary cells such as neuron, adipocytes have been tested in Allele Biotech’s lab as target for modified Boculovirus. To assess the infection efficiency, you can order a pre-made Baculo2Mam-mWasabi GFP or Baculo2Mam-LanRFP control for a test run. Once you order custom or regular Baculo2Mam products, the cost of the control will be credited back.
4) Up to now, little or no cytopathic effects were observed of using baculovirus in mammalian cell cultures.
5) Other points that may be related to GPCR assays in relevance to mimicking natural cellular environment:
a) Delivery of biosensor to cells just prior to assay without establishing cell lines
b) Large insert capacity for expressing long cDNAs.
c) Multiple virus transductions, simultaneous delivery of multiple genes
d) Expression level can be adjusted by viral titer
e) Finally, Baculo2Mam Viruses can be stably stored at 4oC for up to 3 months, and even longer as seed stocks (i.e. titer will drop but still amplifiable).

Promotion of the first week of 2010:

in the spirit of celebrating Allele’s 10th anniversary and in line with the ongoing “get oligos free for a month” program, we offer $20 off for oligos on 3’ TAMRA or FAM modifications.

New product of the week:

iPS specific gene promoter-fluorescent protein reporter lentiviruses.

Tags: bacmam, baculovirus for mammalian cells, biosensors, cell based assay, cell imortalization service, Fluorescent proteins, GPCR, GPCR assays, immortalizaed primary cells, label-free detection, membrane based assay, viral packaging service