Selection of a Novel Anti-Nicotine Vaccine: Influence of Antigen Design on Antibody Function in Mice

Abstract

Anti-nicotine vaccines may aid smoking cessation via the induction of anti-nicotine antibodies (Ab) which reduce nicotine entering the brain, and hence the associated reward. Ab function depends on both the quantity (titer) and the quality (affinity) of the Ab. Anti-nicotine vaccines tested previously in clinical studies had poor efficacy despite high Ab titer, and this may be due to inadequate function if Ab of low affinity were induced. In this study, we designed and synthesized a series of novel nicotine-like haptens which were all linked to diphtheria toxoid (DT) as carrier, but which differed in the site of attachment of linker to nicotine, the nature of linker used, and the handle used to attach the hapten to DT. The resulting hapten conjugates were evaluated in a mouse model, using CpG (a TLR9 agonist) and aluminum hydroxide (Al(OH)3) as adjuvants, whereby Ab titers, affinity and function were evaluated using a radiolabeled nicotine challenge model. A series of additional linkers varying in length, rigidity and polarity were used with a single hapten to generate additional DT-conjugates, which were also tested in mice. Conjugates made with different haptens resulted in various titers of anti-nicotine Ab. Several haptens gave similarly high Ab titers, but among these, Ab affinity and hence function varied considerably. Linker also influenced Ab titer, affinity and function. These results demonstrate that immune responses induced in mice by nicotine-conjugate antigens are greatly influenced by hapten design including site of attachment of linker to nicotine, the nature of linker used, and the handle used to attach the hapten to DT. While both Ab titer and affinity contributed to function, affinity was more sensitive to antigen differences.

Molecular attributes of conjugate antigen influence function of antibodies induced by anti-nicotine vaccine in mice and non-human primates

“…Such conjugation requires attachment of the hapten to the carrier protein, usually via a linker, which can vary in length, rigidity and hydrophilicity. The nicotine hapten, carrier protein, linker and handle to attach the hapten to carrier can all contribute to the immunogenicity of the nicotine conjugate antigens [11][12][13][14][15][16].…”

Squaryl Molecular Metaphors – Application to Rational Drug Design and Imaging Agents

“…These masked compounds in the squaryl entity would benefit further chemical transformations especially allowing for conjugation of biomolecules. These may include Kitson monoclonal antibodies, proteins and novel anti-nicotine vaccines [111]. Table 2 demonstrates the potential usage of squaryl molecular metaphors showing a variety of transformations to give carbonyl functionality.…”

Biologics to treat substance use disorders: Current status and new directions

“…75,[85][86][87] Increased efficacy of a heroin vaccine correlated with higher haptenization ratios in conjugates containing a tetanus toxoid (TT) carrier but not the diphtheria toxin crossreactive material (CRM 197 ) carrier. 88 Yet, haptenization ratio did not correlate with anti-heroin Ab titer nor affinity.…”

“…87 This impressive effort yielded a lead immunogen consisting of the 5-aminoethoxy-nicotine (Hapten 7) conjugated to CRM 197 . 87 The optimized NIC7-CRM 197 adsorbed on alum plus the toll-like receptor (TLR) 9 agonist CpG adjuvant showed promising pre-clinical efficacy in both mice and NHP, 46,87,89 and these candidates were recently evaluated in a clinical trial ( Table 1). Analysis of several lots of NIC7-CRM 197 showed that higher vaccine immunogenicity and efficacy correlated to lower degree of conjugate aggregation, and minimal presence of adducts.…”