Bivalent Recombinant Vaccine for Botulinum Neurotoxin Types A and B Based on a Polypeptide Comprising Their Effector and Translocation Domains That Is Protective against the Predominant A and B Subtypes
| Autor: | Xiaomi Tong, Huei-Hsiung Yang, John K. Brehm, Heidi Agostini, Clifford C. Shone, Yanfang Chu, Virginia Johnson, Joanna McGlashan, Joanna Clancy, Mili Gu, Makie Taal |
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| Rok vydání: | 2009 |
| Předmět: |
Models
Molecular Botulinum Toxins Immunology Gene Expression Biology Immunoglobulin light chain medicine.disease_cause Microbiology law.invention Mice Antigen law Escherichia coli medicine Animals Neurotoxin Botulinum Toxins Type A Vaccines Synthetic Effector Toxin Botulism Survival Analysis Virology Bacterial vaccine Infectious Diseases Microbial Immunity and Vaccines Bacterial Vaccines Recombinant DNA biology.protein Parasitology Antibody |
| Zdroj: | Infection and Immunity. 77:2795-2801 |
| ISSN: | 1098-5522 0019-9567 |
| DOI: | 10.1128/iai.01252-08 |
| Popis: | The clostridial neurotoxins include tetanus toxin and the seven antigenically different botulinum neurotoxins (BoNTs), all of which exert their action by blocking the calcium-mediated release of neurotransmitters (24). The BoNTs act principally on the peripheral nervous system, where they inhibit the release of acetylcholine at the neuromuscular junction, an action that results in a widespread descending flaccid paralysis and ultimately the syndrome botulism. Because of the high potencies of the BoNTs, they are considered potential reagents for bioterrorist use and are currently designated by the Centers for Disease Control and Prevention as category A biothreat agents (1). In their most active forms, the BoNTs consist of two subunits: a light chain (∼50 kDa) linked by a disulfide bond to a heavy chain (∼100 kDa). Structurally, these subunits are arranged into three distinct domains (17, 30): a 50-kDa HC domain that consists of two subdomains (of which the C-terminal subdomain is involved in neuronal acceptor binding), a translocation domain represented by the N-terminal half of the heavy chain (HN domain), and a light-chain, effector domain (LC). Collectively, these domains enable the BoNTs to bind and translocate to within the presynaptic nerve terminal (6), where they act, via highly specific, zinc-dependent protease actions within the LC domain, to disable the process of calcium-mediated transmitter release (24). While architecturally and mechanistically similar, the various serotypes of the BoNTs differ significantly in their primary structures (19) with the result that antibodies raised against one BoNT serotype offer no, or very little, protection against the biological action of another. Separate antigens are therefore required for each serotype to provide complete protection against the full spectrum of BoNTs. Vaccine development is further complicated by the occurrence of subtypes within most of the BoNT serotypes (13). For BoNT serotype A, for example, four subtypes have thus far been identified (designated BoNT/A1 to BoNT/A4) which display between 7 and 16% heterology in their primary nucleic acid sequences (2). These sequence variations occur primarily within surface-exposed regions on the molecule, thus maximizing their impact on antibody binding and neutralization and hence vaccine efficacy. Providing adequate cross-protection against the principal subtypes of each BoNT serotype must therefore be an important consideration in design of both vaccines and antibody-based therapeutics for the BoNTs. Current vaccines for the BoNTs consist of formaldehyde-inactivated toxin complexes which were first developed in the 1950s. Although these vaccines are effective, they require specialized high containment manufacturing facilities and are difficult and expensive to manufacture in large quantities (9). The initial design of recombinant vaccines was undertaken with the rationale of inhibiting a key facet of the biological activity of the BoNTs, such as receptor binding. Thus, first-generation recombinant vaccines under development are based on the receptor-binding domains (HC fragments) of each BoNT. These fragments, produced in Pichia pastoris, have been shown to provide a protective immune response in mice and have recently entered clinical trials (3, 4, 27). The HC fragments derived from the various BoNTs, however, differ markedly in their isoelectric points (pIs 5.7 to 9.1), which make formulation of a multivalent vaccine difficult. More recent studies indicate that antibodies directed against the light chain and the HN region of the BoNT molecule can also provide a neutralizing immune response (5, 6). The LHN fragment of the BoNTs is a polypeptide of ∼100 kDa consisting of the light-chain domain in close association with the translocation domain (Fig. (Fig.1).1). A polypeptide belt from the latter surrounds the light chain under nonreducing conditions. In initial studies, the LHN fragment of BoNT/A was produced by prolonged trypsin digestion of the neurotoxin and shown to be a soluble, immunoreactive fragment (26). Subsequently, LHN fragments from several BoNT serotypes have been produced by recombinant DNA technology and demonstrated to be useful as the core of a range of potential novel therapeutics (10, 29). In the present study, LHN fragment-based vaccines for BoNT/A and BoNT/B are described. A derivative of the LHN/A vaccine is shown to have exceptional efficacy in animal studies providing single-dose protection against BoNT/A subtypes A1, A2, and A3. The LHN/B vaccine is shown to provide protection against BoNT/B subtypes B1 and B4 (nonproteolytic). FIG. 1. Structure and function of the BoNTs. A diagram of the structure of BoNT/A shows the organization of the domains and the composition of the LHN fragment. The HC (binding) domain binds to neuronal receptors, after which the HN (translocation) domain mediates ... |
| Databáze: | OpenAIRE |
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