Simple radiometric method for accurately quantitating epitope densities of hapten-protein conjugates with sulfhydryl linkages

Synthesis of Zearalenone Immunogen and Comparative Analysis of Antibody Characteristics

Background

This study aimed to explore the zearalenone (ZEN) immunogen synthesis method, immunogenicity, and antibody characteristics and to lay a foundation for the establishment of immunoassay methods for ZEN single residue and ZEN and its analogs total residue.

Methods

Based on the molecular structure and active sites of ZEN, oxime active ester (OAE), condensation mixed anhydride (CMA), formaldehyde (FA), and 1,4-butanediol diglycidyl ether method (BDE) were designed and used for immunogen (ZEN-BSA) synthesis. The immunogens were identified by infrared (IR) and ultraviolet (UV) spectra and gel electrophoresis (SDS-PAGE) and were then used to immunize Balb/c mice to prepare ZEN polyclonal antibody (ZEN pAb). The titers and sensitivity of the ZEN pAb were determined by indirect noncompetitive ELISA (inELISA) and indirect competitive ELISA (icELISA), respectively, and its specificity was assessed by the cross-reaction test (CR).

Results

ZEN-BSA was successfully synthesized, and the molecular binding ratios of ZEN to BSA were 17.2 : 1 (OAE), 14.6 : 1 (CMA), 9.7 : 1 (FA), and 8.3 : 1 (BDE), respectively. The highest inELISA titers of ZEN pAb of each group were 1 : (6.4 × 10³) (OAE), 1 : (3.2 × 10³) (CMA), 1 : (1.6 × 10³) (FA), and 1 : (1.6 × 10³) (BDE), respectively. The 50% inhibition concentrations (IC50) for ZEN by icELISA of each group were 11.67 μg/L (OAE), 16.29 μg/L (CMA), 20.92 μg/L (FA) and 24.36 μg/L (BDE), respectively. ZEN pAb from the mice immunized with ZEN-BSA (OAE) and ZEN-BSA (CMA) had class broad specificity to ZEN and its analogs. The CRs of ZEN pAb with α-ZAL, β-ZAL, α-ZOL, β-ZOL, and ZON were 36.53%, 16.98%, 64.33%, 20.16%, and 10.66%, respectively. ZEN pAb from the mice immunized with ZEN-BSA (FA) and ZEN-BSA (BDE) had high specificity for ZEN. The CRs of ZEN pAb with its analogs were all less than 1.0%.

Conclusion

This study demonstrated that the preparation of the class broad-specificity antibodies of ZEN and its analogs can be achieved by immunizing animals with the immunogen ZEN-BSA prepared by the OAE method, while the preparation of highly specific antibodies can be achieved by immunizing animals with the immunogen ZEN-BSA prepared by the FA method. These findings lay the material and technical foundation for immunoassay of ZEN single residue and ZEN and its analogs total residue.

Antibody production and pharmacokinetics of METH in rats following vaccination with the METH vaccine, IXT-v100, adjuvanted with GLA-SE

BACKGROUND

Methamphetamine use disorder continues to be inadequately treated, but improvements are being made in the field of immunotherapeutics, including vaccines, which could provide new options for treatment. Cocaine and nicotine vaccines have been tested clinically, but have yet to elicit the necessary antibody concentrations required to be effective. Methamphetamine vaccines have been tested in multiple nonclinical models and appear promising. Improved adjuvants have the potential to further stimulate the immune system to reach effective levels of antibodies. Previously, the methamphetamine vaccine IXT-v100 was administered with GLA-SE, a toll-like receptor 4 agonist, in mice to produce higher levels of antibodies than when it was administered with two other widely used adjuvants, Alhydrogel and Sigma Adjuvant System.

METHODS

The purpose of this research was to evaluate IXT-v100, given in combination with the adjuvant GLA-SE, to determine its efficacy in antagonizing methamphetamine disposition in a rat pharmacokinetic study. Additional rat studies were conducted to compare the ability of IXT-v100 manufactured with greater hapten densities to elicit higher antibody levels.

RESULTS

As expected based on prior studies with anti-methamphetamine monoclonal antibodies, the antibodies resulting from vaccination with IXT-v100 altered methamphetamine pharmacokinetics by increasing serum concentrations and extending the half-life. Furthermore, intentional variations in the ratio of components during manufacturing led to production of vaccines with higher hapten densities. The higher hapten densities resulted in production of antibodies that maintained the ability to bind methamphetamine with high affinity.

CONCLUSIONS

The results support continued development of IXT-v100 for the treatment of methamphetamine use disorder.

Design, synthesis and biological evaluation of a bi-specific vaccine against α-pyrrolidinovalerophenone (α-PVP) and 3,4-methylenedioxypyrovalerone (MDPV) in rats

α-PVP (α-pyrrolidinovalerophenone) and MDPV (3,4-methylenedioxypyrovalerone) are potent abused stimulants that are members of the synthetic cathinone class of drugs. Although these drugs are taken with recreational intent, high doses can lead to unintended adverse effects including agitation, cardiovascular effects, sympathomimetic syndromes, hallucinations, and psychoses. One possible treatment is the use of a vaccine to block or attenuate adverse medical effects. These studies report the preparation of a vaccine that generates high affinity antibodies specific for both drugs and the pharmacological testing of this vaccine in male rats. Alkylation of a hydroxy-α-PVP analog with an appropriate thiol-bearing linker afforded the hapten. When hapten-conjugated carrier protein was mixed with adjuvant, the resulting vaccine stimulated production of antibodies in male Sprague Dawley rats that were found to significantly reduce α-PVP- and MDPV-induced hyperlocomotion as well as to significantly reduce the concentrations of MDPV drugs in critical organs. The novel vaccine produced high affinity antibodies against MDPV, (R)-MDPV, (S)-MDPV, and α-PVP. Cross-reactivity testing against nine structurally similar cathinones showed very limited binding, and no binding to off-target endogenous and exogenous compounds. Antibodies generated by this bi-specific vaccine also significantly shortened the duration of locomotor activity induced by both drugs up to a dose of 5.6 mg/kg in male rats.

In silico design of knowledge-based Plasmodium falciparum epitope ensemble vaccines

Malaria is a global health burden, and a major cause of mortality and morbidity in Africa. Here we designed a putative malaria epitope ensemble vaccine by selecting an optimal set of pathogen epitopes. From the IEDB database, 584 experimentally-verified CD8+ epitopes and 483 experimentally-verified CD4+ epitopes were collected; 89% of which were found in 8 proteins. Using the PVS server, highly conserved epitopes were identified from variability analysis of multiple alignments of Plasmodium falciparum protein sequences. The allele-dependent binding of epitopes was then assessed using IEDB analysis tools, from which the population protection coverage of single and combined epitopes was estimated. Ten conserved epitopes from four well-studied antigens were found to have a coverage of 97.9% of the world population: 7 CD8+ T cell epitopes (LLMDCSGSI, FLIFFDLFLV, LLACAGLAYK, TPYAGEPAPF, LLACAGLAY, SLKKNSRSL, and NEVVVKEEY) and 3 CD4+ T cell epitopes (MRKLAILSVSSFLFV, KSKYKLATSVLAGLL and GLAYKFVVPGAATPYE). The addition of four heteroclitic peptides - single point mutated epitopes - increased HLA binding affinity and raised the predicted world population coverage above 99%.

Structural investigation of cyclo-dioxo maleimide cross-linkers for acid and serum stability

The size of the acetal ring and the length of the carbon chain strongly influence the serum stability of cyclo-dioxo-based amino-to-thiol coupling reagents.

Optimization of a methamphetamine conjugate vaccine for antibody production in mice

There are still no approved medications for treating patients who abuse methamphetamine. Active vaccines for treating abuse of nicotine and cocaine are in clinical studies, but have not proven effective seemingly due to inadequate anti-drug antibody production. The current studies aimed to optimize the composition, adjuvant and route of administration of a methamphetamine conjugate vaccine, ICKLH-SMO9, in mice with the goal of generating significantly higher antibody levels. A range of hapten epitope densities were compared, as were the adjuvants Alhydrogel and a new Toll-like receptor 4 (TLR4) agonist called GLA-SE. While methamphetamine hapten density did not strongly affect the antibody response, the adjuvant did. Glucopyranosyl lipid A in a stable oil-in-water emulsion (GLA-SE) produced much higher levels of antibody in response to immunization compared with Alhydrogel; immunization with GLA-SE also produced antibodies with higher affinities for methamphetamine. GLA-SE has been used in human studies of vaccines for influenza among others and like some other clinical TLR4 agonists, it is safe and elicits a strong immune response. GLA-SE adjuvanted vaccines are typically administered by intramuscular injection and this also proved effective in these mouse studies. Clinical studies of the ICKLH-SMO9 methamphetamine vaccine adjuvanted with GLA-SE have the potential for demonstrating efficacy by generating much higher levels of antibody than substance abuse vaccines that have unsuccessfully used aluminum-based adjuvants.

Combining Active Immunization with Monoclonal Antibody Therapy To Facilitate Early Initiation of a Long-Acting Anti-Methamphetamine Antibody Response

We hypothesized that an anti-METH mAb could be used in combination with a METH-conjugate vaccine (MCV) to safely improve the overall quality and magnitude of the anti-METH immune response. The benefits would include immediate onset of action (from the mAb), timely increases in the immune responses (from the combined therapy) and duration of antibody response that could last for months (from the MCV). A novel METH-like hapten (METH-SSOO9) was synthesized and then conjugated to immunocyanin monomers of keyhole limpet hemocyanin (IC(KLH)) to create the MCV ICKLH-SOO9. The vaccine, in combination with previously discovered anti-METH mAb7F9, was then tested in rats for safety and potential efficacy. The combination antibody therapy allowed safe achievement of an early high anti-METH antibody response, which persisted throughout the study. Indeed, even after 4 months the METH vaccine antibodies still had the capacity to significantly reduce METH brain concentrations resulting from a 0.56 mg/kg METH dose.