CpG oligodeoxynucleotides are potent immunostimulants. characterization from the vaccine formulation. 1.
June 11, 2017
CpG oligodeoxynucleotides are potent immunostimulants. characterization from the vaccine formulation. 1. Introduction CpGs are oligodeoxynucleotides (ODN) containing unmethylated CpG dinucleotide motifs that possess immunostimulatory properties and are potentially useful as adjuvants . In the first study to describe their action, CpG motifs in bacterial DNA and synthetic ODN were found to enhance B-cell activation in mice . Subsequent studies showed that, in mammals, the immune enhancement is mediated by binding of the CpG ODN to Toll-like receptor 9 (TLR9) found on B cells and, depending on the species, a variety of antigen presenting cells. The interaction of TLR9 with CpG motifs initiates a cascade of events resulting in the activation of B cells and secretion of T helper (Th)1-type cytokines and chemokines . In animal studies, CpG immunostimulation was more efficient if the CpG ODN is chemically coupled to the antigen  suggesting that simultaneous activation of a cell by both antigen and CpG is required for optimal effect. One CpG ODN, designated ODN 2006, is a 24-mer that contains three CpG motifs (5-GTCGTT-3) and has been selected for human use although it stimulates immune responses in a wide range of animals including primates , mice, rats and guinea pigs . SR141716 It is named CPG 7909 or VaxImmune? and is produced by Coley Pharmaceutical Group. A phosphorothioate is certainly included by This ODN backbone, rendering it resistant to nuclease strike and raising its half-life. In the initial Stage I/II vaccine trial of CPG 7909, it had been put into a non-adjuvanted influenza vaccine . Within this trial CPG 7909 didn’t enhance antibody creation significantly. Nevertheless, in a Stage I trial of CPG 7909 with an alum-based hepatitis B vaccine, Engerix-B?, in healthful Canadian adult volunteers, the vaccine gave higher antibody responses weighed against Engerix-B substantially? by itself . The addition of CPG 7909 considerably elevated antigen-specific antibody titers and improved the avidity maturation of IgG1 to hepatitis B surface area antigen . In another Stage 1 trial with Engerix-B?, CPG 7909 could stimulate antibody response in immuno-compromised HIV infected recipients . CPG 7909 is currently being tested in human Phase 1 vaccine trials with several other vaccine candidates, including the malaria antigens Merozoite Surface Protein 1 (MSP142)  and Apical Membrane Antigen 1 (AMA1) , both of which are adsorbed to aluminum hydroxide (Alhydrogel). In this report, we compare the enhancement of antibody response to alum-based malaria vaccine candidates by CPG 7909 and show that this binding of CPG 7909 to the alum is critical. 2. Materials and Methods 2.1. CPG 7909 CPG 7909 (Coley Pharmaceutical Group, Wellesley, MA) has a phosphorothioate backbone and the sequence 5-TCGTCGTTTTGTCGTTTTGTCGTT-3. Clinical lot 207-03-002, a gift under Clinical Trials Agreement from Coley, Rabbit Polyclonal to GPR113. was supplied as 10 mg/ml in 6 mM monobasic sodium phosphate, 94 mM dibasic sodium phosphate, 154 mM sodium chloride. 2.2. Vaccine formulations AMA1-C1 is an equal mixture (by mass) of two recombinant allelic forms of apical membrane antigen 1 (FVO and SR141716 3D7 clones) expressed in depends only on the total anti-AMA1 antibody and not on the relative levels of different subclasses (Mullen et al, unpublished). However, for other vaccines, the possibility exists that not only will binding of CpG to alum affect total antibody, but it may additionally impact on the ability of the resulting antibodies to kill their target. Importantly these results spotlight the need for a physical association of the CpG and antigens for optimal effect. In humans, CPG 7909 has substantially boosted antibody response with Hepatitis B Surface Antigen [17, 18] and with AMA1 (Mullen et al, unpublished) and MSP142 (Martin et al, unpublished) when these antigens were formulated with alum, but not with the un-adjuvanted influenza vaccine . The mouse data presented in this paper are consistent with these human studies, and both are consistent with studies that show a substantial enhancement of antibody production with CpG covalently linked to the antigen . It is unclear if the deleterious impact SR141716 of free CpG around the immunostimulation of bound CpG seen in this study will also be a problem in human vaccines since at the doses used, the amount of free CpG in the mice was several orders higher than could be achieved in humans when used at the recommended dose of approximately 500 g. Nevertheless, these data show that for alum based vaccines, since the effective CpG dose may be related to the bound concentration, it will be important to carefully optimize and characterize the.