Deficient synthesis of class-switched, HIV-neutralizing antibodies to the CD4 binding site and correction by electrophilic gp120 immunogen

Catalytic antibody (catabody) platform for age-associated amyloid disease: From Heisenberg's uncertainty principle to the verge of medical interventions

Quantum mechanics-based design of useful catalytic antibodies (catabodies) failed because of the uncertain structure of the dynamic catalyst-substrate complex. The Catabody Platform emerged from discovery of beneficial germline gene catabodies that hydrolyzed self-proteins by transient covalent pairing of the strong catabody nucleophile with a weak target protein electrophile. Catabodies have evolved by Darwinian natural selection for protection against misfolded self-proteins that threatened survival by causing amyloid disease. Ancient antibody scaffolds upregulate the catalytic activity of the antibody variable (V) domains. Healthy humans universally produce beneficial catabodies specific for at least 3 misfolded self-proteins, transthyretin, amyloid β peptide and tau protein. Catabody are superior to ordinary antibodies because of catalyst reuse for thousands of target destruction cycles with little or no risk of causing inflammation, a must for non-toxic removal of abundant targets such as amyloids. Library mining with electrophilic target analogs (ETAs) isolates therapy-grade catabodies (fast, specific). Ex vivo- and in vivo-verified catabodies specific for the misfolded protein are available to dissolve brain, cardiac and vertebral amyloids. Immunization with ETAs overcomes important ordinary vaccine limitations (no catabody induction, poor immunogenicity of key target epitopes). We conceive electrophilic longevity vaccines that can induce catabody synthesis for long-lasting protection against amyloid disease.

Optimized Replicating Renilla Luciferase Reporter HIV-1 Utilizing Novel Internal Ribosome Entry Site Elements for Native Nef Expression and Function

We previously developed replication-competent reporter HIV-1 (referred to herein as LucR.T2A reporter viruses), utilizing a "ribosome skipping" T2A peptide strategy to link Renilla luciferase (LucR) with Nef expression. The demonstrated utility for HIV-1 vaccine and transmission study applications included measurement of neutralizing antibody (NAb) activity in vaccine sera, improved cell-mediated virus inhibition assays, such as T cell-mediated virus inhibition and antibody-dependent cell-mediated cytotoxicity (ADCC) assays, and humanized mouse models. Herein, we extend our prior work and introduce reporter virus technology for applications that require fully functional Nef. We demonstrate that in CD4(+) T cells productively infected with LucR.T2A reporter viruses, T2A peptide-driven Nef expression and function, such as down-regulation of surface CD4 and MHC-I, were impaired. We overcame this limitation of LucR.T2A reporter viruses and achieved physiological Nef expression and function by engineering novel LucR reporter HIV-1 comprising 11 different internal ribosome entry site (IRES) elements chosen for size and relative activity. A range of Nef expression was observed in 293T cells transfected with the different LucR.IRES reporter virus constructs. Iteratively, we identified IRES reporter genomes that expressed Nef closest to physiological levels and produced virus with infectivity, titers, and replication kinetics similar to nonreporter viruses. Our results demonstrated that LucR reporter activity was stable over multiple replication cycles in peripheral blood mononuclear cells (PBMCs). Furthermore, we analyzed Nef functionality, i.e., down-modulation of MHC-I and CD4, following infection of T cell lines and PBMCs. Unlike LucR.T2A reporter virus, one of the redesigned LucR.IRES reporter viruses [containing the modified encephalomyocarditis virus (EMCV) 6ATR IRES element, "6ATRi"] demonstrated Nef expression and function similar to parental "nonreporter" virus. In a previously validated (nef-independent) T cell-based NAb neutralization assay, LucR.6ATRi reporter virus performed indistinguishably from LucR.T2A reporter virus. In summary, reporter viruses comprising the "6ATRi" element promise to augment HIV-1 vaccine and transmission research approaches requiring a sensitive reporter readout combined with wild-type Nef function.

Identification and Characterization of the Trypanosoma cruzi B-cell Superantigen Tc24

Trypanosoma cruzi causes life-long disease after infection and leads to cardiac disease in 30% of infected individuals. After infection, the parasites are readily detectable in the blood during the first few days before disseminating to infect numerous cell types. Preliminary data suggested that the Tc24 protein that localizes to the T. cruzi membrane during all life stages possesses B-cell superantigenic properties. These antigens facilitate immune escape by interfering with antibody-mediated responses, particularly the avoidance of catalytic antibodies. These antibodies are an innate host defense mechanism present in the naive repertoire, and catalytic antibody–antigen binding results in hydrolysis of the target. We tested the B-cell superantigenic properties of Tc24 by comparing the degree of Tc24 hydrolysis by IgM purified from either Tc24 unexposed or exposed mice and humans. Respective samples were subjected to sodium dodecyl sulfate polyacrylamide gel electrophoresis, silver stained, and the degree of hydrolysis was measured. Data presented in this report suggest that the T. cruzi Tc24 is a B-cell superantigen based on the observations that 1) Tc24 was hydrolyzed by IgM present in serum of unexposed mice and humans and 2) exposure to Tc24 eliminated catalytic activity as early as 4 days after T. cruzi infection.