List Labs currently has over 3300 citations with more being added every month! Within our citations page, we provide the ability to search and sort from over 100 cataloged items that are offered here.

We are honored to supply researchers worldwide with highly purified bacterial toxins that can potentially be instrumental in helping to change the world!

In this post, we’ve gathered all of our current citations for our Diphtheria product group. Please use these citations as a reference and resource for your potentially life-changing work!

Diphtheria Toxin & CRM

Corynebacterium diphtheriae is a Gram-positive, bacterium that infects epithelial cells of the upper respiratory tract and produces diphtheria toxin.  Diphtheria toxin is proteolytically cleaved forming a two-part toxin, held together by a disulfide bridge.  The amino-terminal carries the toxin’s enzymatic activity, capable of ADP-ribosylation and inactivation of translation elongation factor 2 (EF-2).  The carboxy-terminal domain binds to specific host receptors, the heparin-binding EGF-like growth factor (HB-EGF) on human epithelial cells, and translocates the catalytic domain into the cell.  After binding to the cell receptor, the diphtheria toxin is taken up by endocytosis, the pH of the endocytic vesicle drops, and the translocation region of the toxin helps guide the catalytic domain into the host cytoplasm where it is released.  Within the cytoplasm, the diphtheria toxin catalytic domain ADP ribosylates EF-2, terminating protein synthesis and causing the death of the cell.  Diphtheria toxin is highly potent, and as little as one catalytic domain is thought to cause cell death.  In cell culture, diphtheria toxin inhibits protein synthesis and causes death in cells carrying the HB-EGF receptor.  This toxin has been used to specifically eliminate receptor-expressing cells in transgenic mice.

View List Labs Diphtheria toxins for sale.

View some of List Labs Diphtheria related blogs:

Bacterial Toxin Terminology

Toxoids, Toxins and Vaccine Related Terminology

List Labs Reagents Used in Research – January ’18

Carrier Protein Used in Life-Changing Research

Cell Ablation Using Diphtheria Toxin (DT) is an Important Technique for Studying Regeneration in Living Animals

By: Mary N. Wessling, Ph.D. ELS

In this blog we will unravel the terminology describing bacterial toxins. In general, there are at least three ways that bacterial toxins are described in the literature:

• by their biological designation—the genus and/or species from which they come
• by the origin of the toxin, either as innate to the bacterial structure or released by the bacterium into surrounding body fluids
• by the body part that is damaged by the toxin

Below are examples of each:

Biological designation

When described by their biological designation a part of the genus or species name is used for the toxin. For example: Clostridium tetani produces Tetanus toxin and Corynebacterium diphtheriae produces Diphtheria toxin.

Origin of the toxin

Exotoxins (e.g. polypeptides) are toxins released by a cell, whereas endotoxins (e.g. lipopolysaccharides) are an integral part of the bacterial cell wall.

Body part damaged by the toxin

Bacteria may cause disease through their toxins that enter the body via the respiratory tract, gastrointestinal tract, genital tract, and the skin. Enterotoxins mostly affect the gastrointestinal tract. “Entero” comes from the Greek word “enteron” meaning intestine.

Bacterial enterotoxins include examples of exotoxins produced by some strains of Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli).Staphylococcal enterotoxin acts on intestinal neurons to induce vomiting; E. coli producing Shiga toxin causes serious dysentery and can lead to hemorrhagic diarrhea and kidney failure.

You will also see other terms used to designate toxins…

Superantigens: toxins that cause over-reaction

Antigens are characterized by their ability to activate T-cells and other immune system cells; while the T-cell response is a normal part of the immune process, over-activation of T-cells can cause an inflammatory response that can result in shock and multiple organ failure.

Pore-forming toxins that open host cell membranes

Pore-forming toxins (PFT) are toxin proteins with the ability to spontaneously self-assemble forming transmembrane pores in the membrane of target cells. Staphylococcal alpha toxin, also known as alpha-haemolysin, makes specific pores in target cells which are part of the pathology of infection and a valuable tool in construction of nanopores. Tetanolysin is another pore forming toxin produced by C. tetani which can make cells permeable to materials for experimentation.

Intracellular toxins

These toxins have two-part structures and are termed AB toxins. The A stands for “active”, the B for “binding”, for the ways that the two structures cooperatively cause cell damage. In most cases, the B structural element attaches to the cell membrane and provides an entry point for the other part, the A-enzyme component that causes damage to the inside of the cell through its enzymatic activity.

Some AB toxins have more than one B moiety: for example, the cholera toxin has five B proteins that provide entry for the A moiety, so it is designated AB₅. The A moiety is initially a coiled chain but once inside the cell it uncoils, where its enzymatic activity kills the enteric cell.

Ligand-receptor interactions

The actions of exotoxins and endotoxins depend on a process whereby a part of their molecular structure, a ligand, can bind or otherwise interact with a structure on the host cell being attacked, a receptor. Thus, this ligand–receptor interaction is crucial to most diseases produced by bacterial toxins.

Lethal dose 50%

Bacteria cause disease by toxin production, invasion and inflammation. All toxins damage or disrupt the functions of the host cells. The term that describes the level of danger presented to the host by a toxin is “Lethal Dose 50%”, abbreviated LD₅₀; the lower the LD₅₀, the lower the amount of toxin to cause death.

 

By: Mary N. Wessling, Ph.D. ELS

List Biological Laboratories’ (List Labs) catalog of products is related to furthering research in human health and preventing disease, most commonly as the starting materials for vaccine research & development or production around the world. Vaccines are mainly identified for their capacity to prevent diseases that the body’s innate defensive mechanisms (the skin and specialized cells in the blood, for example) can’t resist unaided. However, there are many other uses for these purified materials in medical research, and you will likely encounter wording on our website that is not part of everyday vocabulary for non-scientists. This article is intended to provide a basic understanding of some of the more frequently used terms and aid you in selecting the products most essential to your projects.

Toxin vs. Toxoid

For starters, what is the difference between “toxin” and “toxoid”. Broadly defined, anything that can cause harm to an organism is a toxin. However, for List Labs’ products and in biological usage, a toxin refers to a bacterial or viral product that has harmful effects when it enters the body (List Labs’ toxins are in a highly purified form). A toxoid is a chemically altered toxin that has reduced or no toxicity and is used for its remaining antigenic activity, which can stimulate an immune response.

Take, for example, cholera, a disease produced by Vibrio cholerae bacteria, possibly through contact with body fluids from a person ill with cholera or through contaminated water supply. Cholera causes severe diarrhea, and untreated, it can be fatal. However, the purified List Labs’ cholera toxin by chemical modification becomes a toxoid that lacks toxic activity but retains structures that make it useful for immunization of research animals or stimulation of immune cells in vitro.

How do Toxoids Impact the Immune Process? 

To understand how some List Labs products work, an overview of the immune process is helpful. During the course of a day, we frequently touch, ingest, or breathe in something that has potential to harm the body. Our cells react to this invader: is this a threat, or not, and if so, how serious is the threat?

What is the Innate Immune Response and Its Role in Disease Prevention? 

The innate immune response is the first order of defense in the immune process. There are many different cell types in our body. Some of these cells are equipped by their structural and biochemical components to destroy dangerous microbial invaders–pathogens–quickly. The inflammation that we experience from minor infections is often a sign of this process as cells from the blood destroy the pathogen. This happens quickly, within hours.

Adaptive Immune Response: How B-Cells and T-Cells Defend Against Invaders

Another cellular response system requires a longer time to react to the threat. These cells react by changing from an inactive form to one that will start a more complex defensive process: this is the second step, the adaptive immune response. There are two different classes of cells that comprise the adaptive immune response; they differ by the structures that give them their ability to bind antigens– the invading bacteria and viruses. Both these cells are called lymphocytes; individually, they are the B-lymphocytes (B-cells) and T-lymphocytes (T-cells). Both originate from stem cells in the bone marrow; B and T refer to the place in the body where they mature. T-cells mature in the thymus into several subclasses of T-cells that circulate in the blood and lymph. “Killer” T-cells recognize foreign antigens on cell surfaces (e.g. from viral infection or malignancy). “Helper” T-cells induce B-cells to produce antibodies. “Suppressor” T-cells dampen or regulate the immune response to prevent over-reaction. B-cells mature in the bone marrow and migrate to secondary lymphoid tissues (e.g. spleen and lymph nodes). When they encounter foreign antigens and/or helper T-cells, they are stimulated to divide and expand clonally to produce antibodies and differentiate into plasma cells.

The Importance of Immune Memory in Vaccine Development 

After the B and T-lymphocytes react to an antigen, two results are possible. The first, and desirable result, is that the invader is identified and defeated, leaving behind what might be called its criminal record: immune memory. When the antigen comes creeping back in the future, the adaptive immune system recognizes it and attacks. The second possibility is an over-reaction and lack of cessation of the adaptive immune process that is harmful to the body: an autoimmune condition.

Antigens, Epitopes and Their Role in Vaccines Design

Where do vaccines come into this process? An antigen is a substance that causes the body to mount an immune response against it. Antigens include toxins, bacteria, viruses, or other substances that the body recognizes as foreign or not “self”. Vaccines have structural features similar to structures of the toxin or invading pathogen that can elicit adaptive immunity.

An epitope is a specific molecular region on the surface of an antigen, typically one of many on the antigen, that elicits an immune response and is capable of binding with the specific antibody produced by the response. A toxin has many epitopes that can be recognized by the immune response. The epitopes that are required for toxicity have been altered chemically in toxoids or by specific genetic mutations in inactive mutants; however, many epitopes are retained and can stimulate an adaptive or memory immune response that will be effective against the toxin.

Toxins and Toxoid Products for Vaccine Research at List Labs

Below is a list of toxin and toxoid or inactive mutant pairs of products available to support your research.

Toxin and product numbers	Toxoid	Inactive Mutant
Botulinum Neurotoxin Type A from Clostridium botulinum – 130A, 130B, 9130A	133L
Botulinum Neurotoxin Type B, Nicked, from Clostridium botulinum – 136A, 136B	139
Toxin A from Clostridium difficile – 152C	153
Toxin B from Clostridium difficile – 155A, 155B, 155L	154A
Diphtheria Toxin, Unnicked, from Corynebacterium diphtheriae – 150	151	149
Enterotoxin Type B from Staphylococcus aureus – 122	123
Tetanus Toxin from Clostridium tetani – 190A, 190B	191A, 191B

 

 

By: Rachel Berlin, Marketing Manager

The List Labs website hosts a library of scientific article abstracts related to the research performed using our products called the Citations Page. Visitors can search this library to learn how others have used List Labs’ reagents in their research. This valuable resource is updated monthly with new articles from a wide variety of publications. Check out a few recent articles below:

Botulinum Neurotoxin

• High Yield Preparation of Functionally Active Catalytic-Translocational Domain Module of Botulinum Neurotoxin Type A That Exhibits Uniquely Different Enzyme Kinetics 
• Augmentation of VAMP-catalytic activity of botulinum neurotoxin serotype B does not result in increased potency in physiological systems
• Detection and Quantification of Biologically Active Botulinum Neurotoxin Serotypes A and B using Förester Resonance Energy Transfer-based Quantum Dot Nanobiosensor 

Carrier Proteins

• Complexation hydrogels as potential carriers in oral vaccine delivery systems 
• Efficacy, but not antibody titer or affinity, of a heroin hapten conjugate vaccine correlates with increasing hapten densities on tetanus toxoid, but not on CRM197 carriers

Clostridium difficile toxin

• Catch-slip behavior observed upon rupturing membrane-cytoskeleton bonds
• Immunization with Recombinant TcdB-Encapsulated Nanocomplex Induces Protection against Clostridium difficile Challenge in a Mouse Model
• Clostridium difficile chimeric toxin receptor binding domain vaccine induced protection against different strains in active and passive challenge models 

Lipopolysaccharide (LPS)

• A quantitative method for microstructural analysis of myelinated axons in the injured rodent brain
• Innate immune responses of equine monocytes cultured in equine platelet lysate
• Cationic peptides from peptic hydrolysates of rice endosperm protein exhibit antimicrobial, LPS-neutralizing, and angiogenic activities

Diphtheria toxin

• Auditory Neuropathy after Damage to Cochlear Spiral Ganglion Neurons in Mice Resulting from Conditional Expression of Diphtheria Toxin Receptors
• Monocytes Promote Crescent Formation in Anti-Myeloperoxidase Antibody-Induced Glomerulonephritis
• Myeloid progenitor cluster formation drives emergency and leukaemic myelopoiesis

Don’t see the reagent you’re interested in? You can search the citations by product, year, publication, or by the type of cell, animal, assay, protein or research. Check it out today!

By: Mary N. Wessling, Ph.D. ELS

Cross-Reacting Materials: The Motor Behind Conjugate Vaccines

Vaccines in history

The history and practice of vaccination as protection against viral infection is often thought to begin with Edward Jenner’s discovery that  cowpox, a viral infection of cows, prevented smallpox in humans. However, it had long been suspected that survivors of smallpox seemed to be immune to further infection. Attempts to induce this immunity, referred to as variolation, had likely been practiced in Africa, Asia, and China, and only introduced to Europe in the 18^th century. [1] Jenner, though, can certainly be credited for his scientific, experimental approach; his inoculation of an 8-year-old boy eventually was documented in his 1798 book An Inquiry into the Causes and Effects of the Variolae vaccinae. A disease discovered in the Western Counties of England [2]. The number of lives that have been saved from misery and death is impossible to grasp; estimates of mortality from the disease before Jenner range between 30 and 35%.

What are carrier proteins, and why are they important in immunology?

Vaccines are often less effective in very young children whose immune systems are immature. For the past 35 years, vaccines have been “conjugated”—combined with a carrier protein –a cross-reactive material (CRM)–that enhances the immunogenicity of polysaccharide antigens. [3] The carrier protein CRM197 (Product #149), under consideration here, is a mutant version of Diphtheria toxin, in which the single amino acid exchange of a glycine in position 52 to a glutamic acid renders the protein non-toxic: it is one of the most widely used and highly effective carrier proteins [5]. List Labs’ CRM197 has been used in a wide range of medical research, leading to a better understanding of the mechanism behind serious illnesses at all stages of the human life cycle. Most of the studies to date have employed animal models because direct research in humans would be ethically impossible.

Carrier protein CRM 197 could be used to protect premature infants from necrotizing colitis

Starting at the beginnings of life–necrotizing colitis (NEC) destroys the intestinal epithelium and is responsible for 20% to 50% of the mortality in premature infants, as well as causing significant long-term disability among its survivors. In an in vivo experiment using puppies exposed to NEC, Su et al (2013) used List’s CRM 197 as an antagonist to the epithelial protective E-cadherin/b-catenin complex. Their results suggest that administration of the heparin-binding epidermal-like growth factor could protect premature babies from developing NEC, and also that it could be used in treatment of diseases resulting in intestinal injury.

List Labs’ carrier protein used in Alzheimer’s research

A disease that causes misery at the other end of life, Alzheimer’s disease, is associated with amyloid plaques, specifically amyloid-beta, the subject of intense investigation. Vingtdeux et al (2016) in a murine study developed a novel vaccine against the pathologically relevant A-beta pE3 using List’s CRM197 as a carrier protein for epitope presentation.

CRM197 carrier protein impacts humans over a lifetime 

In mid-life, three of the research applications of List Labs’ CRM 197 have potential for bringing health to human populations. First, heroin addiction: Jalah et al (2015) sought to develop a vaccine against heroin addiction, one that would block its biological effects by sequestering the drug in the blood, preventing it from crossing the brain barrier. The researchers used List’s CRM197 along with a heroin/morphine hapten conjugate of previously established efficacy to improve its antinociceptive effects.

Another life-shortening threat, diabetic nephropathy is, in 40% of all cases, the leading cause of end-stage kidney disease. You et al (2013) injected CRM 197 in mice for 6 weeks to investigate the mechanism whereby the podocytes (cells in the Bowman’s capsule that filter the blood, foot-shaped, ergo podo…) are injured. The culprit was identified as the proinflammatory M1 subset of macrophages; finding a way to attenuate the effect of the M1 macrophages on the podocytes suggests a new therapeutic approach.

And a final example: Human disease can be caused by contamination of milk products by aflatoxins—certainly a life-long concern. Researchers immunized Holstein Friesian heifers with an experimental vaccine based on the immunogen anaflatoxin B1 AnAFB1] [10]. They then studied the response to AnAFB1 conjugated with List Labs CRM197 carrier proteins to determine the efficacy of inducing antibodies specific to AFB1.

 

REFERENCES

1. Riedel S. Edward Jenner and the history of smallpox and vaccination. Proceedings (Baylor University, Medical Center. 2005 May; 18(1):21-5. PMCID: PMC1200696
2. Lakhani S. Early clinical pathologists: Edward Jenner (1749-1823). Journal of Clinical Pathology. 1992 Sep; 45(9): 756–758. PMCID: PMC495097
3. Bröker M. Potential protective immunogenicity of tetanus toxoid, diphtheria toxoid and Cross Reacting Material 197 (CRM 197) when used as carrier proteins in glycoconjugates. Human Vaccines & Immunotherapeutics. 2016; 12(3): 664-667. PMCID: PMC4964734
4. Murphy K. Janeway’s Immunobiology, 8^th Ed. London: Garland Science, 2012:718.
5. Möwinger S, Resemann A, Martin CE, et al. Cross Reactive Material 197 glycoconjugate vaccines contain privileged conjugation sites. Scientific Reports 2016 Feb 4; 66:20488. doi: 10.1038/srep20488. PMID: 26841683
6. Su Y, Yang J, Besner GE. HB-EGF promotes intestinal restitution by affecting integrin-extracellular matrix interactions and intercellular adhesions. Growth Factors. 2013 Feb; 31(1):39-55. doi: 10.3109/08977194.2012.755966. PMID: 23305395
7. Vingtdeux V, Zhao H, Chandakkar P, et al. A modification-specific peptide-based immunization approach using CRM197 carrier protein: Development of a selective vaccine against pyroglutamate Aβ peptides. Molecular Medicine. 2016 Nov 28;22. doi: 10.2119/molmed.2016.00218. PMCID: PMC5263057
8. Jalah R, Torres OB, Mayorov AV, et al. Efficacy, but not antibody titer or affinity, of a heroin hapten conjugate vaccine correlates with increasing hapten densities on tetanus toxoid, but not on CRM197 carriers. Bioconjugate Chemistry. 2015 Jun 17;26(6):1041-53. doi: 10.1021/acs.bioconjchem.5b00085. PMID: 25970207
9. You H, Gao T, Cooper TK, et al. Macrophages directly mediate renal injury.  Am J Physiol Renal Physiol. 2013 Dec 15;305(12):F1719-27. doi: 10.1152/ajprenal.00141.2013. PMID: 24173355
10. Giovati L, Gallo A, Masoero F, et al. Vaccination of heifers with anaflatoxin improves the reduction of aflatoxin B1 carry over in milk of lactating dairy cows. PLoS One. 2014 Apr 8;9(4):e94440. doi: 10.1371/journal.pone.0094440. PMCID: PMC3979841

By: Suzanne Canada, Ph.D.

Diphtheria toxin is an important tool used for selective killing (ablation) of cells for research purposes.  Using this technique, dubbed “toxin receptor–mediated cell knockout” when it was first used [1], researchers can selectively remove a specific type of cell in a live mouse without having to generate transgenic “knockout” animals, which can be more time-consuming.  The animals are engineered to express a diphtheria toxin (DT) receptor on the surface of a specific cell type.  These animals are normal until exposed to DT, which acts as a potent inhibitor of protein synthesis and kills only those cells that express the DT receptor.  This technique is a powerful tool to explore the role of specific cell types in disease, and is being used to study both the recovery of pituitary cells and the role of T-cells in inflammatory colitis.

Applications in Pituitary Cell Regeneration

The pituitary gland plays an important role in the endocrine system, which presides over growth and development, stress response (adrenal glands), and metabolism (thyroid gland).  Willems and colleagues [2] have been studying the regeneration of the pituitary—research that could lead to methods or therapies to heal pituitary deficiencies.  Transgenic mice that express a DT receptor on the membrane of the growth hormone (GH) cells were treated with DT, which selectively killed those cells.  The researchers then monitored the ability of these ablated cells to regenerate.  Using this technique, they found that stem cells in the pituitary participate in the regeneration process.  Younger mice had a greater ability to recover from injury to the pituitary than older mice.  However, if the injury was prolonged (11 days compared with 3 days) the ability for stem cells to react and aid in recovery could be delayed or even blocked. These researchers may find how stem cells could be activated to boost regeneration of a damaged pituitary gland.

Insights into T-Cell Regulation in Inflammatory Diseases

Cell regeneration also plays an important role in the digestive system: researchers are studying how T-cells regulate inflammation in the gut.  Increases in activated T-cells are associated with active flare-ups of ulcerative colitis and Crohn’s disease [Kappler, 2000].  To that end, Boschetti and colleagues [3] used DT to selectively deplete CD4+, CD25+, and Foxp3+ regulatory T-cells [T-regs] in the gut of transgenic mice.  Using that process, the researchers were able to ablate >95% of the T-regs. The proliferation and recovery of the various T-cell subsets in the lymph nodes and colon was monitored using flow cytometry.  By monitoring the recovery of the T-regs, the researchers found that inflammation causes regulatory T-cells to move to the colon lamina propria, and that those cells could suppress proliferation of CD4+ effector cells in vitro.  Although the Foxp3+ T-regs could not completely prevent colitis in the mice, they did reduce the severity of inflammation in the gut.

This technique is a powerful approach to selectively remove certain cells in mice and other model systems where the animals do not naturally have a DT receptor.  The DT from List Labs is recommended for this purpose because its high purity produces the best desired effect.

To read about even more uses of Diphtheria Toxin and other List Labs products, browse our Citations page. Contact us today with any questions or inquiries regarding our CDMO products and services.

 

References

1. Michiko Saito , Takao Iwawaki , Choji Taya , Hiromichi Yonekawa , Munehiro Noda , Yoshiaki Inui , Eisuke Mekada , Yukio Kimata , Akio Tsuru & Kenji Kohno (2001) Diphtheria toxin receptor|[ndash]|mediated conditional and targeted cell ablation in transgenic mice. Nature Biotechnology 19, 746–750. PMID: 11479567
2. Willems, C; Fu, Q; Roose, H; Mertens, F; Cox, B; Chen, J; Vankelecom, H (2016) Regeneration in the Pituitary After Cell-Ablation Injury: Time-Related Aspects and Molecular Analysis.  Endocrinology 157 705-21. PMID: 26653762
3. Boschetti, G; Kanjarawi, R; Bardel, E; Collardeau-Frachon, S; Duclaux-Loras, R; Moro-Sibilot, L; Almeras, T; Flourié, B; Nancey, S; Kaiserlian, D (2016) Gut Inflammation in Mice Triggers Proliferation and Function of Mucosal Foxp3+ Regulatory T Cells but Impairs Their Conversion from CD4+ T Cells. J Crohn’s and Colitis advanced access publication 30 June 2016.  PMID: 27364948 
4. Kappeler A1, Mueller C. (2000)The role of activated cytotoxic T cells in inflammatory bowel disease.  Histol Histopathol. 2000 Jan;15(1):167-72. PMID: 10668207

By: Md. Elias, Ph.D, Senior Scientist

List Labs is one of the leading manufacturers of high quality adjuvants from bacterial sources. Our highly purified adjuvants for research and development are Tetanus Toxoid (Product #191), Cholera Toxin B Subunit (Product #104), Diphtheria Toxin CRM₁₉₇ Mutant (Product #149), Adenylate Cyclase Mutant, Cya-AC^– (Product #198L), Pertusis Toxin Mutant (Product #184), and LPS and its derivatives (Products #400, #401, #421, #423, #433, #434). GMP grade material is available by custom order.

In immunology, an adjuvant is a component that enhances and/or potentiates the immune responses (humoral and /or cell mediated) to an antigen and modulates it to achieve the desired immune responses. Adjuvants can be used for various reasons: (i) to enhance the immunogenicity of antigens; (ii) to reduce the amount of antigen or the number of immunizations needed for protective immunity; (iii) to improve the efficacy of vaccines in immune-compromised persons; (iv) to increase functional antibody titer; or (v) as antigen delivery systems for the uptake of antigens by the mucosa (1-3). Brief descriptions of List Labs products that have potential uses as vaccine adjuvants or immune modulators are provided below. For more details, please visit www.ListLabs.com.

Tetanus Toxoid (Product #191): Tetanus toxoid is prepared by formaldehyde inactivation of pure neurotoxin (Product #190). There are FDA approved vaccines that use a tetanus toxoid antigen to protect children and adult against tetanus such as DAPTACEL and Tripedia, and others that use it as a carrier in conjugate vaccines against various pathogens. For example, MenHibrix^® is an FDA approved vaccine where tetanus toxoid has been conjugated to Neisseria meningitidis serogroup C and Y capsular polysaccharides and Hib capsular polysaccharide. Several other tetanus toxoid conjugated vaccines are in research and investigation stages such as Type III group B streptococcal polysaccharide-tetanus toxoid conjugate vaccine (4). Information on our entire family of Tetanus products can be found at https://listlabs.com/products/tetanus-toxins-&-related-products/.

Cholera Toxin B subunit (Products #103B and #104): Cholera toxin B subunit (CTB) is the cell binding domain of cholera toxin protein complex. The holotoxin consists of a single A subunit bearing ADP-ribosyl-transferase activity surrounded by five B subunits that bind to GM1 ganglioside receptors on mammalian cell surfaces and facilitate entrance of the A subunit into cells. The non-toxic CTB has been shown to be an efficient mucosal adjuvant and carrier molecule for the generation of mucosal antibody responses and/or induction of systemic T-cell tolerance to linked antigens. Due to the ubiquitous presence of the GM1 ganglioside receptor on eukaryotic cell membranes, CTB has been extensively used as a conjugate and non-conjugate vaccine adjuvant in a wide variety of model systems.

A CTB-urease conjugated vaccine has been shown to prevent infection by Helicobacter pylori, a bacterium that infects greater than 50% of world population and can cause a variety of gastrointestinal diseases (5). A series of studies have been carried out to develop CTB carrier based vaccines to prevent HIV-1 (6) and West Nile Virus infections (7). CTB has been used as a component of a skin patch for transcutaneous immunization against hepatitis B virus in a mouse model (8). Besides the adjuvant activity, recent studies show that CTB can suppress immunopathological reactions in allergy and autoimmune diseases such as Crohn’s disease (9). Information on our entire family of Cholera products can be found at https://listlabs.com/products/cholera-toxins/.

Diphtheria Toxin CRM₁₉₇ Mutant (Product #149): CRM₁₉₇ is a non-toxic mutant of diphtheria toxin lacking the ADP-ribosylation activity (10). CRM₁₉₇ results from a naturally occuringsingle base change (glutamic acid to glycine) in the toxin gene which is immunologically indistinguishable from the native diphtheria toxin. CRM₁₉₇ functions as a carrier for polysaccharides and haptens making them immunogenic (11, 12). It is utilized as a carrier to develop conjugate vaccines for diseases such as pneumococcal and meningococcal infections. MenACWY-CRM is an approved vaccine to protect adults and adolescents against disease caused by meningococcal serogroups A, C, W-135 and Y. Information on our entire family of Diphtheria products can be found at https://listlabs.com/products/diphtheria-toxins/.

Adenylate Cyclase Toxoid, Cya-AC^– (Product #198L): A genetically modified adenylate cyclase toxin (ACT) lacking adenylate cyclase activity (CyaA-AC^–) has been produced (13). Although the catalytic activity is destroyed, CyaA-AC^– is still cell invasive and able to induce an immune response to co-administered pertussis antigens (14, 15).  CyaA-AC^– has been shown to promote delivering of vaccine antigens into the cytosol of major histocompatibility complex (MHC) class I antigen-presenting cells (16). CyaA-AC^– has been used as a tool to deliver antigens to T-cells in anti-cancer immunotherapeutic vaccines (17, 18).

Pertussis Toxin Mutant (Product #184): List Labs produces Pertussis Toxin Mutant, a genetically inactivated form of pertussis toxin where mutations were introduced to abolish the catalytic activity of the S1 subunit while the toxin complex still retains the cell binding ability (19). A pertusis toxin mutant has been used as an adjuvant or as a carrier to promote an immune response. These studies indicated that pertussis toxin mutant possesses adjuvant properties with the ability to encourage both local and systemic responses, to promote T helper cell responses to co-administered antigens and to favor the production of Th1/Th17 cells, important in mediating host immunity to infectious pathogens (20). Pertusis toxin binds to the cell receptor, TLR4 which activates Rac and subsequently causes various effects depending on the type of cell treated (21). The toxin or binding oligomer induces dendritic cell maturation in a TLR4-dependent manner (22). Information on our entire family of Pertussis products can be found at https://listlabs.com/products/pertussis-toxins-&-virulence-factors/.

LPS and its derivatives: List Labs provides LPS and various derivatives: highly purified HPT^TM LPS from Escherichia coli O113 (Product #433); Ultar Pure Escherichia coli O111:B4 LPS (Product #421); Escherichia coli O55:B5 LPS (Product #423); Ultra pure LPS from Salmonella Minnesota R595 (Product #434); Lipid A Monophosphoryl from Salmonella Minnesota R595 (Product #401) and highly purified HPT^TM LPS from Bordetella pertusis strain 165 (Product #400). For other LPS products please go to our product website. These LPS products are widely used as vaccine adjuvants and immune stimulators.

LPS is a potent stimulator of the vertebrate innate immune system mediated by macrophages and dendritic cells and generates a rapid response to infectious agents. Structural patterns common to diverse LPS molecules are recognized by Toll-like receptors (TLR) and accessory proteins in serum.  LPS released from bacterial membranes is bound to LPS binding protein (LBP) in serum, transferred to CD-14, an LPS receptor glycoprotein, and presented to the TLR-4-MD-2 complex, stimulating production of cytokines. LPS has a wide range of uses in research and drug development.  It may be used to stimulate immune cells and investigate the innate immune responses.  In drug development, structurally modified LPS forms, such as monophophoryl lipid A (MPLA) have been used as adjuvants in a wide range of vaccine formulations. MPLA, a TLR4 agonist has been formulated with liposomes, oil emulsions, or aluminium salts for several vaccines such as malaria vaccine (known as RTS,S) that is comprised of MPLA and a detoxified saponin derivative, QS-21 (3). Information on our entire family of Lipopolysaccharides can be found at https://listlabs.com/products/lipopolysaccharides/.

List Labs specializes in producing high quality adjuvants for vaccine development and is interested in partnering with others on new projects.  See some of our special projects or contact us for more information.

1. Lee S.,Nguyen M.T. Recent advances of vaccine adjuvants for infectious diseases. Immune Netw. 2015, 15(2): 51-7. PMID: 25922593
2. Petrovsky N., Aguilar J.C. Vaccine adjuvants: current state and future trends. Immunol Cell Biol.2004, 82(5): 488-96. PMID: 15479434 
3. Alving C.R., Peachman K.K.,Rao M., Reed S.G. Adjuvants for human vaccines. Curr Opin Immunol. 2012, 24 (3):310-5. PMID: 22521140 
4. Baker C.J., Rench M.A., McInnes P. Immunization of pregnant women with group B streptococcal type III capsular polysaccharide-tetanus toxoid conjugate vaccine. 2003. 21(24)3468-72. PMID: 12850362
5. Guo L., Li X., Tang F., He Y., Xing Y., Deng X., Xi T. Immunological features and the ability of inhibitory effects on enzymatic activity of an epitope vaccine composed of cholera toxin B subunit and B cell epitope from Helicobacter pylori urease A subunit. Appl Microbiol Biotechnol. 2012, 93(5):1937-45. PMID: 22134639
6. Matoba N., Kajiura H., Cherni I., Doran J.D., Bomsel M., Fujiyama K., Mor T.S. Biochemical and immunological characterization of the plant-derived candidate human immunodeficiency virus type 1 mucosal vaccine CTB-MPR. Plant Biotechnol J.2009, 7(2):129-45. PMID: 19037902
7. Tinker J.K., Yan J., Knippel R.J., Anayiotou P., Ornell K.A. Immunogenicity of a West Nile virus DIII-cholera toxin A2/B chimera after intranasal delivery. Toxins (Basel).2014, 6(4):1397-418. PMID: 24759174
8. Anjuere F., George-Chandy A., Audant F., Rousseau D., Holmgren J., Czerkinsky C. Transcutaneous immunization with cholera toxin B subunit adjuvant suppresses IgE antibody responses via selective induction of Th1 immune responses. J Immunol.2003, 170(3):1586-92. PMID: 12538724
9. Sun J.B., Czerkinsky C.,Holmgren J. Mucosally induced immunological tolerance, regulatory T cells and the adjuvant effect by cholera toxin B subunit. Scand J Immunol. 2010, 71(1):1-11. PMID: 20017804
10. Pappenheimer Jr. A.M., Uchida T., Harper A.A. An immunological study of the diphtheria toxin molecule. 1972, 9(9):891-906. PMID: 4116339
11. Gupta R.K., Siber G.R. Reappraisal of existing methods for potency testing of vaccines against tetanus and diphtheria. 1995, 13(11): 965-6. PMID: 8525688
12. Benaissa-Trouw B., Lefeber D.J, Kamerling J.P., Vliegenthart J.F., Kraaijeveld K., Snippe H. Synthetic polysaccharide type 3-related di-, tri-, and tetrasaccharide-CRM (197) conjugates induce protection against Streptococcus pneumoniae type 3 in mice. Infect Immun.2001, 69(7):4698-701. PMID: 11402020
13. Simsova M., Sebo P., Leclerc C. The adenylate cyclase toxin from Bordetella pertussis–a novel promising vehicle for antigen delivery to dendritic cells. Int J Med Microbiol. 2004, 293(7-8):571-6. PMID: 15149033
14. Macdonald-Fyall J., Xing D., Corbel M., Baillie S., Parton R., Coote J. Adjuvanticity of native and detoxified adenylate cyclase toxin of Bordetella pertussistowards co-administered antigens. 2004, 22(31-32):4270-81. PMID: 15474718
15. Cheung G.Y., Xing D., Prior S., Corbel M.J., Parton R., Coote J.G. Effect of different forms of adenylate cyclase toxin of Bordetella pertussis on protection afforded by an acellular pertussis vaccine in a murine model. Infect Immun.2006, 74(12):6797-805. PMID: 16982827
16. Osicka R., Osicková A., Basar T., Guermonprez P., Rojas M., Leclerc C., Sebo P. Delivery of CD8(+) T-cell epitopes into major histocompatibility complex class I antigen presentation pathway by Bordetella pertussis adenylate cyclase: delineation of cell invasive structures and permissive insertion sites. Infection Immunity, 2000, 68(1): 247-256. PMID: 10603395
17. Dadaglio G., Morel S., Bauche C.,  Moukrim Z., Lemonnier F.A., Van Den Eynde B.J., Ladant D., Leclerc C.  Recombinant adenylate cyclase toxin of Bordetella pertussisinduces cytotoxic T lymphocyte responses against HLA*0201-restricted melanoma epitopes. Int Immunol. 2003 15(12):1423-30. PMID: 14645151
18. Fayolle C., Ladant D., Karimova G., Ullmann A., Leclerc C. Therapy of murine tumors with recombinant  Bordetella pertussisadenylate cyclase carrying a cytotoxic T cell epitope. J Immunol. 1999, 162(7):4157-62. PMID: 10201941
19. Brown D.R.,Keith J.M., Sato H., Sato Y. Construction and characterization of genetically inactivated pertussis toxin. Dev Biol Stand. 1991, 73:63-73. PMID: 1778335
20. Nasso M., Fedele G., Spensieri F., Palazzo R., Costantino P., Rappuoli R., Ausiello C.M. Genetically detoxified pertussis toxin induces Th1/Th17 immune response through MAPKs and IL-10-dependent mechanisms. J Immunol. 2009, 183(3):1892-9. PMID: 19596995
21. Nishida M.,Suda R., Nagamatsu Y., Tanabe S., Onohara N., Nakaya M., Kanaho Y., Shibata T., Uchida K., Sumimoto H., Sato Y., Kurose H. Pertussis toxin up-regulates angiotensin type 1 receptors through Toll-like receptor 4-mediated Rac activation. J Biol Chem. 2010, 285(20):15268-77. PMID: 20231290
22. Wang ZY., Yang D., Chen Q., Leifer C.A., Segal D.M., Su S.B., Caspi R.R., Howard Z.O., Oppenheim J.J. Induction of dendritic cell maturation by pertussis toxin and its B subunit differentially initiate Toll-like receptor 4-dependent signal transduction pathways. Exp Hematol. 2006, 34(8):1115-24. PMID: 16863919

By: Karen Crawford, Ph.D., President

In 1983, List Labs introduced Diphtheria Toxin to the research community. Researchers have purchased Diphtheria Toxin for various uses. One common use is cell ablation. The receptor for Diphtheria Toxin is also called heparin-binding EGF-like growth factor (HB-EGF). This receptor, located on several cell types, binds Diphtheria Toxin, allowing the toxin to enter and kill these cells. Transgenic mice have been developed to express the diphtheria toxin receptor on dendritic cells allowing their depletion. Diphtheria Toxin, Unnicked, from Corynebacterium diphtheriae (Product #150) is an active native enzyme, a useful tool for your research.

Information on our entire family of Diphtheria products, including Diphtheria Toxoid (Product #151) and the mutant CRM197 (Product #149) can be found on our website. Other uses of Diphtheria Toxin and technical information can be found on our Knowledge Base & Support Portal.