The COVID-19 pandemic is a worldwide health emergency which calls for an unprecedented race for vaccines and treatment. In developing a COVID-19 vaccine, we applied technology previously used for MERS-CoV to produce a prefusion-stabilized SARS-CoV-2 spike protein, S-2P. To enhance immunogenicity and mitigate the potential vaccine-induced immunopathology, CpG 1018, a Th1-biasing synthetic toll-like receptor 9 (TLR9) agonist was selected as an adjuvant candidate. S-2P in combination with CpG 1018 and aluminum hydroxide (alum) was found to be the most potent immunogen and induced high titer of neutralizing antibodies in sera of immunized mice against pseudotyped lentivirus reporter or live wild-type SARS-CoV-2. In addition, the antibodies elicited were able to cross-neutralize pseudovirus containing the spike protein of the D614G variant, indicating the potential for broad spectrum protection. A marked Th1 dominant response was noted from cytokines secreted by splenocytes of mice immunized with CpG 1018 and alum. No vaccine-related serious adverse effects were found in the dose-ranging study in rats administered single- or two-dose regimens of S-2P combined with CpG 1018 alone or CpG 1018 with alum. These data support continued development of CHO-derived S-2P formulated with CpG 1018 and alum as a candidate vaccine to prevent COVID-19 disease.
Intracellular pathogenic microorganisms and toxins exploit host cell mechanisms to enter, exert their deleterious effects as well as hijack host nutrition for their development. A potential approach to treat multiple pathogen infections and that should not induce drug resistance is the use of small molecules that target host components. We identified the compound 1-adamantyl (5-bromo-2-methoxybenzyl) amine (ABMA) from a cell-based high throughput screening for its capacity to protect human cells and mice against ricin toxin without toxicity. This compound efficiently protects cells against various toxins and pathogens including viruses, intracellular bacteria and parasite. ABMA provokes Rab7-positive late endosomal compartment accumulation in mammalian cells without affecting other organelles (early endosomes, lysosomes, the Golgi apparatus, the endoplasmic reticulum or the nucleus). As the mechanism of action of ABMA is restricted to host-endosomal compartments, it reduces cell infection by pathogens that depend on this pathway to invade cells. ABMA may represent a novel class of broad-spectrum compounds with therapeutic potential against diverse severe infectious diseases.
The different genes that encode mammalian spectrins give rise to proteins differing in their apparent stiffness. To explore this, we have compared the thermal stabilities of the structural repeats of brain spectrin subunits (αII-and βII) with those of erythrocyte spectrin (αI-and βI). The unfolding transition mid-points (T m ) of the 36 αII-and βII-spectrin repeats extend between 24 and 82°C, with an average higher by some 10°C than that of the αI-and βI-spectrin repeats. This difference is reflected in the T m -s of the intact brain and erythrocyte spectrins. Two of three tandem-repeat constructs from brain spectrin showed strong cooperative coupling, with elevation of the T m of the less stable partner corresponding to coupling free energies of about −4.4 and −3.5 kcal mol −1 . The third tandem-repeat construct, by contrast, showed negligible cooperativity. Tandem-repeat mutants, in which a part of the 'linker' helix that connects the two domains was replaced by a corresponding helical segment from erythroid spectrin, showed only minor perturbation of the thermal melting profiles, without breakdown of cooperativity. Thus the linker regions, which tolerate few point-mutations without loss of cooperative function, have evidently evolved to permit conformational coupling in specified regions. The greater structural stability of the repeats in αII-and βII-spectrin may account, at least in part, for the higher rigidity of brain compared to erythrocyte spectrin.Spectrin arose in evolution with the metazoa to meet the need for structures that strengthen cell adhesions and stabilize the plasma membrane against the forces of animal movement (1). The protein also plays a part in organizing plasma membrane signalling complexes (1, 2). Spectrin occurs as an (αβ) 2 tetramer, specialized for cross-linking actin filaments to membrane constituents. Both the α and β chains are largely made up of consecutive triplehelical repeating units of about 106 amino acids (3, 4); these act in ensemble as spacers between actin-binding domains in the β-subunits at opposite ends of the tetramers, and some contain binding sites for proteins such as ankyrin or for aminophospholipids (5, 6). *Author for correspondence: Xiuli An, Red Cell Physiology Laboratory, 310 E 67 th St, New York, NY10021, Tel: 212-570-3247; Fax: 212-570-3195. xan@nybloodcenter.org. HHS Public Access Author Manuscript Author ManuscriptAuthor Manuscript Author ManuscriptThe number of spectrin genes increased during evolution with the advent of vertebrates.Invertebrates have one α-spectrin and, one β-spectrin with 16 complete triple-helical repeats and a β Heavy subunit with 30 complete triple helices. Vertebrates have four genes encoding 'conventional' β subunits (βI-IV) that have 16 complete triple helical modules, and one β Heavy subunit that has 30 triple helices (βV-spectrin) (1). Mammals have gained an additional α-spectrin by duplication of the pre-existing α-spectrin gene (7). There is now clear evidence of functional specialization of the two mammalian α-...
Herpes simplex virus type 2 (HSV-2) is the causative pathogen of genital herpes and is closely associated with the occurrence of cervical cancer and human immunodeficiency virus (HIV) infection. The absence of an effective vaccine and the emergence of drug resistance to commonly used nucleoside analogs emphasize the urgent need for alternative antivirals against HSV-2. Recently, ABMA [1-adamantyl (5-bromo-2-methoxybenzyl) amine] has been demonstrated to be an inhibitor of several pathogens exploiting host-vesicle transport, which also participates in the HSV-2 lifecycle. Here, we showed that ABMA inhibited HSV-2-induced cytopathic effects and plaque formation with 50% effective concentrations of 1.66 and 1.08 μM, respectively. We also preliminarily demonstrated in a time of compound addition assay that ABMA exerted a dual antiviral mechanism by impairing virus entry, as well as the late stages of the HSV-2 lifecycle. Furthermore, in vivo studies showed that ABMA protected BALB/c mice from intravaginal HSV-2 challenge with an improved survival rate of 50% at 5 mg/kg (8.33% for the untreated virus infected control). Consequently, our study has identified ABMA as an effective inhibitor of HSV-2, both in vitro and in vivo, for the first time and presents an alternative to nucleoside analogs for HSV-2 infection treatment.
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