Sulfonate-isosteric replacement examined within heroin-hapten vaccine design

Heroin overdose and addiction remain significant health and economic burdens in the world today costing billions of dollars annually. Moreover, only limited pharmacotherapeutic options are available for treatment of heroin addiction. In our efforts to combat the public health threat posed by heroin addiction, we have developed vaccines against heroin. To expand upon our existing heroin-vaccine arsenal, we synthesized new aryl and alkyl sulfonate ester haptens; namely aryl-mono-sulfonate (H_MsAc) and Aryl/alkyl-di-sulfonate (H_(Ds)2) as carboxyl-isosteres of heroin then compared them to our model heroin-hapten (H_Ac) through vaccination studies. Heroin haptens were conjugated to the carrier protein CRM₁₉₇ and the resulting CRM-immunoconjugates were used to vaccinate Swiss Webster mice following an established immunization protocol. Binding studies revealed that the highest affinity anti-heroin antibodies were generated by the H_MsAc vaccine followed by the H_Ac and H_(Ds)2 vaccines, respectively (H_MsAc > H_Ac≫H_Ds2). However, neither the H_MsAc nor H_(Ds)2 vaccines were able to generate high affinity antibodies to the psychoactive metabolite 6-acetyl morphine (6-AM), in comparison to the H_Ac vaccine. Blood brain bio-distribution studies supported these binding results with vaccine efficiency following the trend H_Ac > H_MsAc ≫ H_(Ds)2 The work described herein provides insight into the use of hapten-isosteric replacement in vaccine drug design.