What Does It Take to Bring New Nano Antibodies (nAbs) to the Hands of Researchers?

Judging from the hundreds of papers published using camelid VHH antibodies as reagents, there are probably thousands of researchers who have experience with this type of antibodies by now. We like to call the ~15kD camelid VHH antibody nano antibody or nAb^TM. Once someone experiences how well a nAb works for co-IP using a fluorescent protein as tag, they often wonder what it takes to bring nAbs to broader use.

The success of a nAb project starts with the antigen presentation. It is critical to build the capability to produce large quantities of recombinant antigen for immunization. At Allele, our scientists also established some unique presentation formats for traditionally difficult targets (e.g. large membrane proteins).

After llama immunization, the next step is screening. With the goal of creating large scale nano antibodies against diverse targets, we have developed multiple high throughput screening methods to cover very large, diverse libraries generated from immunized animals. The technologies will continue to evolve as the scale of nAb generation continues to expand. We have the ability to functionally screen for site-blocking antibodies and antibodies that only recognized natively folded targets, or targets in their naturally occurring presentations.

A nAb isolation project does not end with the obtaining of a cDNA clone. Or, if it does, the nAb is probably not as great as what Allele Biotech has been offering. In our hands, all nAbs go through an engineering step beginning with the generation of a 3D structural model of the isolated clone. We use structure-guided design to alter the protein, allowing us to improve its properties. This includes increasing affinity, solubility, or altering the protein to improve performance for specific applications. We also like to use known structures of traditional monoclonal antibodies to assist camelid VHH antibody engineering against specific targets.

With a finalized clone in hand, the next step is to establish protocols for commercial production. The Allele team spends a tremendous amount of effort aimed solely at high-yield, low-cost recombinant VHH antibody production in a variety of formats, so that the costs for other scientists to take advantage of these great reagents can be kept as low as possible.

Last but not the least, nAb labeling, including conjugating stable soluble VHH antibody to solid supports for immunoprecipitation or to fluorophores for detection, requires additional expertise and tight operation control. However, our vision is to have a modular system for antibody labeling that will enable the end user to select from a variety of fluorophores and other detection tags, which can be instantaneously and irreversibly coupled via simple mixing.

Note added: we work with commercial (diagnostic and clinical) partners from developing nAbs all the way to the market. We have expert scientists available to customers and licensees for consultation and troubleshooting antibody- and imaging-related questions and problems.

New Allele Biotech Publication on Stem Cells

Feeder-Free Reprogramming of Human Fibroblasts with Messenger RNA
Current Protocols in Stem Cell Biology • November 13, 2013
DOI: 10.1002/9780470151808.sc04a06s27

Authors: Luigi Warren, Jiwu Wang
This unit describes a feeder-free protocol for deriving induced pluripotent stem cells (iPSCs) from human fibroblasts by transfection of synthetic mRNA. The reprogramming of somatic cells requires transient expression of a set of transcription factors that collectively activate an endogenous gene regulatory network specifying the pluripotent phenotype. The necessary ectopic factor expression was first effected using retroviruses; however, as viral integration into the genome is problematic for cell therapy applications, the use of footprint-free vectors such as mRNA is increasingly preferred. Strong points of the mRNA approach include high efficiency, rapid kinetics, and obviation of a clean-up phase to purge the vector. Still, the method is relatively laborious and has, up to now, involved the use of feeder cells, which brings drawbacks including poor applicability to clinically oriented iPSC derivation. Using the methods described here, mRNA reprogramming can be performed without feeders at much-reduced labor and material costs relative to established protocols.

Allele iPSC Service and Technology Licensing Contact: http://www.allelebiotech.com/cell-line-and-culture-services/#ips-line

New Allele Product of the Month: FP-nAb™ products for 100% pull-down

When Great is not Good Enough—VHH Antibodies Engineered for 10 Fold Affinity Increase

http://blog.allelebiotech.com/2013/10/1697/

Single Domain antibodies (VHH fragments, nanobodies, or as we call them, nAbs) have been generated by injecting llamas with ligand-bound GPCR for the purpose of obtaining crystals of active-state structures. Such structural information could be critical in understanding drug functions and screening for new drugs. The unique ability of VHH fragments to fit into protein-protein complex crevices and hold proteins together was demonstrated by two Nature publications from Brian Kobilka’s group at Stanford ([1, 2], also see Allele Newsletter of Sep 4th, 2013). The nano antibody used in those studies, Nb80, showed affinity towards only the active state of the target GPCR.

However, even with an antibody as great as Nb80, the authors were only able to co-crystal GPCR beta2-adrenoceptor (b2AR) with high affinity agonists, not its natural agonists such as adrenaline. In yet another Nature paper published just now, the Kobilka lab showed that Nb80 could be further improved by 10 times in affinity, through in vitro evolution [3]. They presented Nb80 on the surface of yeast using an existing yeast display system, then applied standard limited mutagenesis and magnetic separation technologies for screening. After about 5 rounds of selection, a new version of VHH Nb6B9 was isolated that bound to ligand-loaded GPCR with a kD of 6.4 nM. For the first time, a co-crystal of b2AR-adrenoline was made.

Rasmussen et al. Nature, 2011 Structure of a nanobody-stabilized active state of the b2 adrenoceptor
Rasmussen et al. Nature, 2011 Crystal structure of the b2 adrenergic receptor–Gs protein complex
Ring et al. Nature, 2013 Adrenaline-activated structure of b2-adrenoceptor stabilized by an engineered nanobody

Top 10 List of Most Viewed AlleleBlogs in 2011

The ballot is in—among the “usual suspect” hot topics, iPS takes the top honor and most entries; Camelid antibodies, although not really presented as a typical AlleleBlog in 2011, made it to the top 3. shRNA cloning and RNAi screening are still on a lot of people’s minds, so it seems.

Method: total visits to each blog since our new webpage was launched in July was counted.

1) Fusion of the Transcription Domain to iPS Factors Radically Enhances Reprogramming
http://blog.allelebiotech.com/2011/10/fusion-of-the-transcription-domain-to-ips-factors-radically-enhances-reprogramming/

2) Methods of iPSC Generation Update
http://blog.allelebiotech.com/2011/08/methods-of-ipsc-generation-update/

3) About 50 Papers Cited the Use of GFP-Trap Camelid Antibody So Far in 2011
http://blog.allelebiotech.com/2011/09/about-50-papers-cited-the-use-of-gfp-trap-camelid-antibody-so-far-in-2011/

4) Big Potential in Using Protozoans for Producing Mammalian Proteins
http://blog.allelebiotech.com/2011/09/big-potential-in-using-protozoans-for-producing-mammalian-proteins/

5) How do you make shRNA-expressing viruses for function screening?
http://blog.allelebiotech.com/2011/11/how-do-you-make-shrna-expressing-viruses-for-function-screening/

6) Creating ground-state human iPSCs
http://blog.allelebiotech.com/2011/10/creating-ground-state-human-ipsc/

7) Recombinase-Mediated Cassette Exchange (RMCE) and Integrase Swappable in vivo Targeting Element (InSITE)
http://blog.allelebiotech.com/2011/03/recombinase-mediated-cassette-exchange-rmce-and-integrase-swappable-in-vivo-targeting-element-insite/

8) Development of Cell Lines from iPSCs for Bioassays
http://blog.allelebiotech.com/2011/11/development-of-cell-lines-from-ipscs-for-bioassays/

9) Choosing siRNA, shRNA, and miRNA for Gene Silencing
blog.allelebiotech.com/2010/02/choosing-sirna-shrna-and-mirna-for-gene-silencing/

10) Allele Biotech’s Box Swap Program
http://blog.allelebiotech.com/2009/07/allele-biotechs-box-swap-program/

Have a successful 2012!

From AlleleBlog: http://blog.allelebiotech.com/2011/12/top-10-list-of-most-viewed-alleleblogs-in-2011/

About 50 Papers Cited the Use of GFP-Trap Camelid Antibody So Far in 2011

With their ability to quantitatively pulldown GFP-tagged proteins, GFP-Trap (or RFP-Trap for DsRed-derived fluorescent proteins) beads have gained ground in becoming the reagent of choice for immuno-coprecipitation. The complexes isolated from GFP-Trap agarose or magnetic beads can be easily analyzed without interference from light or heavy IgG chains typically present after monoclonal or polyclonal antibody precipitation. Since the market launch of GFP-Trap, in each of the past 3 years, the number of publications citing GFP-Trap more has than doubled and there is no sign of that rate slowing down any time soon.

In 2011 alone, 48 research groups have published their results with data generated through use of GFP-Trap (not including other related products such as GFP-Booster, GFP-MultiTrap). Research topics in these recent publications include identification of domains of the zinc finger protein 638 (ZNF638) that interacts with C/EBP? when promoting adipocyte differentiation [1]; identification of phosphorylation site on Cdc42-associated kinase (Ack) by LC-MS/MS after immunoprecipitation [2]; and analysis of the activities of myosin heavy-chain kinases (MHCKs) in wild-type vs Htt mutant Dictyostelium discoideum, a cellular model for studying the Huntingon disease [3].

The use of GFP-Trap beads is a simple bind-wash-elute procedure that involves just one antibody already immobilized on either agarose or magnetic beads. Camelid antibodies, especially their VHH single domain fragments such as those used in GFP-Trap or RFP-Trap, are very stable (they can be shipped and temporarily stored at room temperature). The consistency of performance is very high; as a matter of fact, this line of products requires the lowest amount of technical support among all of our products. If you are still using tags like FLAG, V5, HA, etc., you should consider trying GFP as both a fluorescence and co-IP tag in your future experiments for obtaining results you previously could not obtain.

New Product of the Week: Non-Integrating iPSC Generation Kits. First of its kind on the market. Click to read more about mRNA-based reprogramming.

Promotion of the Week: Save 15% to save the environment by using EcoCulture Dishes at 30% less plastic for better imaging. Code: 091911DISH when call or email us.

Blog References:
[1] Meruvu, S. et al. “Regulation of Adipocyte Differentiation by the Zinc Finger Protein ZNF638″ JBC 2011
[2] Shen, H. et al. “Constitutive activated Cdc42-associated kinase (Ack) phosphorylation at arrested endocytic clathrin-coated pits of cells that lack dynamin” Molecular Biology of the Cell 2011
[3] Wang, Y. et al. “Dictyostelium huntingtin controls chemotaxis and cytokinesis through the regulation of myosin II phosphorylation” Molecular Biology of the Cell 2011

Expanding the Camelid Antibody Product Line

From AlleleBlog http://allelebiotech.com/blogs/

While Chromotek GFP-Trap resin has become one of the best sellers from the Allele Biotech’ Camelid Antibody product line, more products have been added that will prove to be great tools for GFP-related research.

GFP is a powerful tool to study protein localization and dynamics in living cells. However, the photo stability and the quantum efficiency of GFP are not sufficient for Super-Resolution Microscopy (e.g. 3D-SIM or STED) of fixed samples from cells expressing GFP-fusion proteins to visualize specific structures. Furthermore, many cell biological methods such as HCl treatment for BrdU-detection, the EdU-Click-iT™ treatment or heat denaturation for FISH lead to disruption of GFP signal.

Now we offer our GFP-Trap Booster for reactivation, boosting and stabilization of GFP, suitable for acquiring strong and long lasting signals from GFP-fusion proteins. It is based on a specific GFP-binding protein as in GFP-Trap but coupled to the fluorescent dye ATTO 488 (from ATTO-TEC). For information, please read the product description of this week New Product of the Week: GFP-Trap booster, ABP-CM-GBOOSTR, http://www.allelebiotech.com/shopcart/index.php?c=221&sc=158

Promotion of the week: All mTFP1 and mWasabi fusion plasmids are 30% off for this week only

Preview of future new product: a similarly high quality product, the RFP-Trap that pulls down DsRed derived proteins including mRFP1, mCherry, mOrange, mPlum but also mRuby and RFP-tagged fusion proteins.

Using 2A “self-cleaving” peptide in bicistronic mammalian expression

http://allelebiotech.com/blogs/2010/03/using-2a-%E2%80%9Cself-cleaving-peptide-in-bicistronic-mammalian-expression/

Multiple promoters or internal ribosomal entry sites (IRES) have been used for the production of multiple proteins from the same vector. Potential drawbacks with multiple promoters on viral vectors include unstable genome and interference between promoters. IRES is a relatively large sequence that can cause problems in virus packaging, especially for viruses with very limited genome size such as AAV. In addition, it is required that the start of the second ORF is fairly close to the IRES, adding difficulties to cloning.

2A or 2A-like peptide (collectively called 2A peptide here) is used by several families of viruses, the best known foot-and-mouth disease virus of the Picornaviridae family, for producing multiple polypeptides. Although called a "self-cleaving" peptide or protease site, the mechanism by the 2A sequence for generating two proteins from one transcript is by ribosome skipping. a normal peptide bond is impaired at 2A, resulting in two discontinuous protein fragments from one translation even.

The 2A-based bicistronic expression has been used for several years, but recently gained much more popularity due to its successful use in iPSC generation that required 2 to 4 factors working in concert. Even expression of all factors can be achieved when 2A peptides are used for multiple protein production, due to near 100% efficiency of the 2A "cleavage" at each site, and no interference between multiple 2A sites. Early work used a 36 amino acid sequence as 2A peptide, which was later reduced to about half that size from mutation and screening. Commercial vectors utilizing 2A for co-expression of cDNA and fluorescent protein and/or drug resistance genes have not been available until now. Allele Biotech has introduced a number of such plasmids, establishing another First-to-the-market as it has done many times previously in its 10 year history.

New product of the week 03-29-10 to 04-04-10:

Alleleustrious pmTFP1-2A Bicistronic mammalian expression vector, ABP-FP-T2A10, $399.

Promotion of the week 03-29-10 to 04-04-10:

Buy any GFP-Trap beads or kits, get polyclonal anti-GFP (ABP-PAB-PAGFP10) at half size for FREE!

Intracellularly Expressed Camelid Single-Domain Antibody (VHH) Counteracts Cytotoxicity Seen in Agricultural Epidemics

The advantages of camelid antibodies with only the heavy chains have been exploited for therapeutic use or as novel research tools such as immunoprecipitation trap (e.g. GFP-Trap). These so-called nanobodies are small in size (14-15kD), highly stable, and capable of binding to epitopes that traditional antibodies are normally not able to bind. Doyle et al. published a paper in JBC last week demonstrating that when expressed inside cells (intrabody), the VHH fragment can provide antitoxicity protection against deoxynivalenol (DON) or 15-acetyl0deoxynivalenal (15-AcDON), common toxins involved in agriculture infection Fusarium.



Camelid antibodies against low molecular weight 15-AcDON were isolated by immunizing llama with 15-AcDON-BSA protein conjugate as published earlier by the same group of researchers in Canada. As demonstrated previously, the small nanobody derived from camelid antibody can be highly expressed inside target cells without causing much cytotoxicity by itself. Images generated by confocal immuno-microscopy showed that VHH is evenly distributed throughout the cytosol. The antitoxin effects were specific, effective, and apparently dose-dependent.



This report, albeit using a yeast model system instead of natural targets of the relevant plant disease, opens doors to increased tests of using VHH fragments for broader applications in agriculture and more fields other than therapeutics.


Doyle et al. 09-2009

http://www.jbc.org/cgi/doi/10.1074/jbc.M109.045047

Allele Annouces New Products Based on Camelid Antibodies

090209 San Diego—Allele Biotech formally announced today that it has signed an agreement to distribute products from ChromoTek GmbH, a German company with a focus on camelid antibody fragment based precipitation and detection reagents. Single-domain antigen binding fragment, also called VHH or nanobody, can be derived from heavy chain-only antibodies produced by animals in the camel family. The small size and special structures of VHH enable their efficient binding into areas not normally accessible to larger IgG antibodies. Although GFP is a commonly used tag in fusion proteins for imaging, it has not yet become a widely used tag for precipitation. With the introduction of the first VHH-based research reagent GFP-Trap, GFP-fusions will become a desirable tool for pulldown. GFP-Trap is immobilized anti-GFP nanobody, which with a simple procedure, can result in quantitative depletion or isolation of GFP-fusions.



Applications of GFP-Trap may include ChIP-CHIP, CLIP, co-IP, enzyme activity analysis (see Allele Biotech’s product group main page for sample publications). Other products such as anti-RFP and anti-GFP monoclonal antibodies that may be used after GFP-fusion precipitation are now also available from Allele Biotech. “VHH fragments have great potentials in both therapeutic and basic research,” said Allele’s CEO Dr. Jiwu Wang, “The agreement will significantly strengthen Allele Biotech's position in the antibody field”. Allele Biotech started with a grant from the NIH in 2000 to develop ways to display and select antibodies. It participated in a collaborative project on yeast display for selecting antibodies against cancer antigens in 2007 for the NCI. After acquiring Orbigen in 2008, Allele has thousands of antibodies in its product line.

Camelid Antibodies--background

When it was discovered that animals in the camel family produce antibodies with no light chains, the idea that a single-domain fragment can bind as well as a full 4-chain antibody formed a breakthrough. So far it has been a relatively less known one.

Smaller antibody fragments have been tested for therapeutic uses because classical IgG antibodies are too bulky to penetrate tissues well, and very expensive to produce. Different combinations of antigen-binding variable regions are used, e.g. scFv, Fab, diabody, all to some degree of success. In comparison, the N-terminal domain of camelid antibodies, termed VHH domain, represents a naturally evolved, only 13-15 kD in size, fully functional target binding fragment with many advantages.

The only other known species outside camelidae family that has heavy chain antibodies is particular cartilaginous fish, nurse shark. Although the arrangement of CDRs is somewhat different between the camel and shark heavy chain variable regions, they share many characteristics such as extremely high stability (maintaining functions after100 C heat and extreme pH treatment).

Accumulating reports have demonstrated the therapeutic potentials of camelid antibody-based fragments in treating cancer, neural diseases, even use in hair dandruff preventing shampoo. For basic research, the tiny antigen binders can be used as tools for quantitative pull down with unmatched efficiency, recognizing previously inaccessible enzyme cleft as antigens, and providing libraries for binding partner selection.

Allele Biotech has been working on display antibody selection from its early days through an NIH grant, and recently carried out an NIH/NCI contract for scFv yeast display in collaboration with AvantGen. By working with Chromotek on camelid antibody products, we hope to combine our superior fluorescent proteins with the best antibody candidates and display technologies to move the capture and signaling fields forward in significant ways.

The product line will be formally announced by AlleleNews shortly.