The need for SARS-CoV-2 next-generation vaccines has been highlighted by the rise of variants of concern (VoC) and the long-term threat of emerging coronaviruses. Here, we design and characterize four categories of engineered nanoparticle immunogens that recapitulate the structural and antigenic properties of prefusion SARS-CoV-2 Spike (S), S1 and RBD. These immunogens induce robust S-binding, ACE2-inhibition, and authentic and pseudovirus neutralizing antibodies against SARS-CoV-2. A Spike-ferritin nanoparticle (SpFN) vaccine elicits neutralizing titers (ID 50 > 10,000) following a single immunization, while RBD-Ferritin nanoparticle (RFN) immunogens elicit similar responses after two immunizations, and also show durable and potent neutralization against circulating VoC. Passive transfer of IgG purified from SpFN- or RFN-immunized mice protects K18-hACE2 transgenic mice from a lethal SARS-CoV-2 challenge. Furthermore, S-domain nanoparticle immunization elicits ACE2 blocking activity and ID50 neutralizing antibody titers >2,000 against SARS-CoV-1, highlighting the broad response elicited by these immunogens.

Active immunization is an emerging potential modality to combat fatal overdose amid the opioid epidemic. In this study, we described the design, synthesis, formulation, and animal testing of an efficacious vaccine against fentanyl. The vaccine formulation is composed of a novel fentanyl hapten conjugated to tetanus toxoid (TT) and adjuvanted with liposomes containing monophosphoryl lipid A adsorbed on aluminum hydroxide. The linker and hapten N -phenyl- N -(1-(4-(3-(tritylthio)propanamido)phenethyl)piperidin-4-yl)propionamide were conjugated sequentially to TT using amine- N -hydroxysuccinimide-ester and thiol–maleimide reaction chemistries, respectively. Conjugation was facile, efficient, and reproducible with a protein recovery of >98% and a hapten density of 30–35 per carrier protein molecule. In mice, immunization induced high and robust antibody endpoint titers in the order of >10 6 against the hapten. The antisera bound fentanyl, carfentanil, cyclopropyl fentanyl, para -fluorofentanyl, and furanyl fentanyl in vitro with antibody-drug dissociation constants in the range of 0.36–4.66 nM. No cross-reactivity to naloxone, naltrexone, methadone, or buprenorphine was observed. In vivo , immunization shifted the antinociceptive dose–response curve of fentanyl to higher doses. Collectively, these preclinical results showcased the desired traits of a potential vaccine against fentanyl and demonstrated the feasibility of immunization to combat fentanyl-induced effects.

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Opioid use disorders and fatal overdose due to consumption of fentanyl-laced heroin remain a major public health menace in the United States. Vaccination may serve as a promising potential remedy to combat accidental overdose and to mitigate the abuse potential of opioids. We previously reported the heroin and fentanyl monovalent vaccines carrying, respectively, a heroin hapten, 6-AmHap, and a fentanyl hapten, para- AmFenHap, conjugated to tetanus toxoid (TT). Herein, we describe the mixing of these antigens to formulate a bivalent vaccine adjuvanted with liposomes containing monophosphoryl lipid A (MPLA) adsorbed on aluminum hydroxide. Immunization of mice with the bivalent vaccine resulted in IgG titers of >10 5 against both haptens. The polyclonal sera bound heroin, 6-acetylmorphine, morphine, and fentanyl with dissociation constants ( K d ) of 0.25 to 0.50 nM. Mice were protected from the anti-nociceptive effects of heroin, fentanyl, and heroin +9% (w/w) fentanyl. No cross-reactivity to methadone and buprenorphine was observed in vivo . Naloxone remained efficacious in immunized mice. These results highlighted the potential of combining TT-6-AmHap and TT- para- AmFenHap to yield an efficacious bivalent vaccine that could ablate heroin and fentanyl effects. This vaccine warrants further testing to establish its potential translatability to humans.