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J. immunostimulatory activity of CpG ODN was probed at the molecular level by microarray. Results show that a small group of inducers rapidly up-regulated a large network genes following CpG treatment of mice. This stimulatory activity is usually quenched by suppressors that down-regulate the expression of targeted genes, including most of the inducers. These findings shed light on the mechanism underlying CpG mediated immune activation and therapeutic activity. Immunomodulatory properties of CpG ODN Synthetic oligodeoxynucleotides (ODN) made up of immunostimulatory CpG motifs interact with Toll-like receptor 9 to initiate an immunostimulatory cascade that culminates in the maturation, differentiation and/or proliferation of multiple cell types, including lymphocytes, dendritic cells, NK cells, monocytes and macrophages (Gursel et al, 2002; Hemmi et al, 2000; Hornung et al, 2002; Klinman et al, CZC-8004 1996; Stacey et al, 1998; Takeshita et al, 2001). Together, these secrete cytokines and chemokines that create a pro-inflammatory (IL-1, IL-6, IL-18 and TNF) and Th1-biased (IFNg and IL-12) immune milieu (Ballas et al, 1996; Halpern et al, 1996; Hemmi et al, 2000; Ishii et al, 2002; Klinman et al,1996; Krieg et al,1995; Takeshita et al, 2001). In humans, TLR9 is usually primarily present within human B cells and plasmacytoid DC, while in mice multiple cells of the myeloid lineage (including monocytes, macrophages and DC) express TLR 9 and directly respond to CpG activation (Bauer et al, 2001; Kadowaki et al, 2001; Krug et al, 2001). USE OF CpG ODN AS VACCINE ADJUVANTS Vaccine applications: CpG ODN improve the protective immunity induced by AVA Anthrax Vaccine Adsorbed (AVA) is the single vaccine licensed to prevent human anthrax in the US. AVA requires a series of 6 immunizations over 18 months to induce the production SACS of neutralizing antibodies against the protective antigen (PA) of anthrax toxin (Pittman et al, 2001). CZC-8004 Anthrax spores designed for aerosol delivery were released in the US by bioterrorists in 2001, causing morbidity, mortality, and common panic (Lane et al, 2001). That event underscored the need for any vaccine that induced protective immunity more rapidly than AVA and managed protection without repeated boosts (Lane et al, 2001). One strategy to achieve these goals entails adding CpG ODN to AVA. The ability of CpG ODN to promote Th1 responses and induce the maturation and activation of professional antigen presenting cells suggested they might be useful vaccine adjuvants (Branda et al, 1996; Krieg et al,1998; Moldoveanu et al, 1998). Previous studies on this topic established that CpG ODN could both accelerate and magnify the immune response elicited by AVA (Klinman et al, 2007; Klinman et al, 2006; Xie et al, 2005). As seen in Table I, adding CpG ODN to AVA increased the titer of serum neutralizing Ab of A/J mice by 10-fold (Xie et al, 2005). The survival of vaccinated mice following anthrax spore challenge was also significantly improved by immunizing with CpG adjuvanted AVA. In contrast, delaying the administration of CpG ODN until after AVA immunization yielded almost no booster effect, consistent with adjuvant activity requiring co-delivery with antigen (Table I). These findings were confirmed in studies of rhesus macaques, where co-administering CpG ODN with AVA induced a six-fold higher Ab response than AVA alone (Klinman et al, 2004). Serum from primates vaccinated with AVA plus CpG ODN transferred protection against anthrax spore challenge to murine recipients (Table I) (Klinman et al, 2004). A clinical trial examining the response of 69 normal healthy volunteers to 0.5 ml of AVA plus 1 mg of CpG ODN was conducted. Results from that study exhibited that in humans, the inclusion of CpG ODN significantly accelerated the induction of protective immunity and increased serum IgG anti-PA titers by 9-fold when compared to AVA alone (p .05) (Rynkiewicz et al, 2005). Table I CpG ODN as adjuvant for AVA with high (310?9 M) or low (10?11 CZC-8004 M) concentrations.