CpG Oligonucleotides

What are CpG oligonucleotides?

CpG oligonucleotides (CpG ODNs) are synthetic, single-stranded oligonucleotides characterized by the presence of unmethylated cytosine-phosphate-guanine (CpG) motifs. These molecules are powerful immunostimulators, acting via Toll-like receptor 9 (TLR9) to incite powerful innate and adaptive immune systems. Alfa Chemistry has a broad offering of CpG ODNs, with applications in vaccine adjuvants, cancer immunotherapy, and new drug delivery systems.

Figure 1. Chemical structure of CpG recognition motif and sites for modification^[1].

Structural overview of CpG oligonucleotides

CpG ODNs typically possess one or more unmethylated CpG dinucleotide motifs (5-CG-3) that are able to stimulate the immune system of the body (primarily by way of Toll-like receptor 9 (TLR9)). These are usually single-stranded, and backbones are usually phosphorothioate-modified, so they're very resistant to nuclease degradation inside the cell.

By sequence and structure, there are three types of CpG ODNs: A, B, and C.

1) Class A: Containing palindromic sequences and poly G tails at the 3' end, they are capable of forming advanced structures, such as stem-loop structures or G-quadruplexes, which contribute to their immunostimulatory activity.

2) Class B: Existing as a monomer and usually does not form advanced structures, but its ability to rapidly enter late endosomes and activate TLR9 gives it an important role in immune responses.

3) Class C: Combining the features of Class A and B, containing both palindromic sequences and no poly G tail, and is capable of activating TLR9 in both early endosomes and late endosomes.

Immunomodulatory Properties of CpG Oligonucleotides

CpG ODNs exert a profound influence on both innate and adaptive immunity.

• Activation of dendritic cells, macrophages, and NK cells.
• Promotion of Th1-biased immune responses via cytokine induction (e.g., IFN-α and IL-12).
• Recruitment of T cells to target sites, enhancing tumor and pathogen immunity.

Figure 2. Toll-like receptor 9 (TLR9) signaling pathway(s) upon CpG-ODN stimulation^[2].

What can CpG oligonucleotides be used for?

Vaccine Adjuvants

What is CpG adjuvant? CpG adjuvant is a synthetic compound derived from oligodeoxyribonucleotides (ODN), also called cytosine-phosphate-guanine oligodeoxynucleotides. The adjuvant can direct dendritic, macrophage, and B cells (by triggering Toll-like receptor 9 (TLR9)), boost antigen presentation, increase antibody release, and indirectly trigger T and NK cells. CpG adjuvants function in 3 basic ways: activation of immune cells, induction of immune response, and enhanced vaccine effectiveness.

CpG ODNs are a common adjuvant for improving vaccine efficiency. They increase immunogenicity by activating innate immune cells and initiating adaptive immunity, which helps reduce the antigen dose per dose of vaccine.

Example:

• CpG1018: CpG1018 is used in Hepatitis B vaccine and gives a better immune response than older aluminum-based adjuvants.
• CpG2006: Integrated into the COVID-19 vaccine platform to support immune activation and protection.

CpG ODN adjuvanted vaccines have excelled in fighting infectious diseases like anthrax and flu; 20 or more formulations are currently in trials.

Cancer Immunotherapy

CpG ODN is administered as a direct immunotherapeutic and as a combination therapy in oncology. CpG ODN activates TLR9 to drive Th1 cytokines, die dendritic cells, and NK and T cells to become more cytotoxic.

These are the therapeutic advantages:

• Enhancement of tumor-specific immune response.
• Use with chemotherapy and radiotherapy can be beneficial.

CpG ODN, for instance, has shown anti-tumor activity in breast and liver cancer by creating a strong cytotoxic T lymphocyte (CTL) response and collaborating with existing therapy.

CpG Oligonucleotide Development at Alfa Chemistry

Alfa Chemistry is a therapeutic CpG ODN development company. Anywhere in the CpG ODN production process you face difficulty, we can help you at an early stage.

• Target selection.
• Sequence design of CpG oligonucleotides.
• Synthesis and chemical modification of CpG oligonucleotides.
• Purification and analysis of CpG oligonucleotides.
• Delivery system selection or development of CpG oligonucleotides.
• Nonclinical evaluation of CpG oligonucleotides.
• Scale-up of CpG oligonucleotides.

CpG ODNs are novel immunotherapy and vaccine tools with unparalleled versatility and performance. Alfa Chemistry's extensive CpG ODN catalog meets the ever-increasing demand for biomedical research and therapeutic development, guaranteeing excellent products for every scientific investigation.

Our products and services are for research use only and cannot be used for any clinical purposes.

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