Small molecule metalloprotease inhibitor with in vitro, ex vivo and in vivo efficacy against botulinum neurotoxin serotype A.

Botulinum neurotoxins (BoNTs) are the most toxic substances known to mankind and are the causative agents of the neuroparalytic disease botulism. Their ease of production and extreme toxicity have caused these neurotoxins to be classified as Tier 1 bioterrorist threat agents and have led to a sustained effort to develop countermeasures to treat intoxication in case of a bioterrorist attack. While timely administration of an approved antitoxin is effective in reducing the severity of botulism, reversing intoxication requires different strategies.

The identification and biochemical characterization of drug-like compounds that inhibit botulinum neurotoxin serotype A endopeptidase activity.

A robust, high-throughput, two-tiered assay for screening small molecule inhibitors against botulinum neurotoxin serotype A was developed and employed to screen 16,544 compounds. Thirty-four compounds were identified as potent hits employing the first-tier assay. Subsequently, nine were confirmed as actives by our second-tier confirmatory assay.

Progress toward development of an inhalation vaccine against botulinum toxin.

The looming threat of bioterrorism has enhanced interest in the development of vaccines against agents such as botulinum toxin. This in turn has stimulated efforts to create vaccines that are effective by the oral and inhalation routes. Recently, considerable progress has been made in creating an inhalation vaccine against botulism.

The role of the interchain disulfide bond in governing the pharmacological actions of botulinum toxin.

All serotypes of botulinum toxin possess a disulfide bond that links the heavy chain and light chain components of the holotoxin. Experiments were done to assess the functional significance of this covalent bond, and the work was facilitated by use of mercurial compounds that modify residues in the vicinity of the catalytic site. The data indicated that reduction of the interchain disulfide bond had two major effects: 1).

Immunologic characterization of spasmodic dysphonia patients who develop resistance to botulinum toxin.

The immune status of six spasmodic dysphonia patients who became resistant to botulinum toxin was compared to that of a series of patients who remained responsive. The two groups were similar in terms of age, sex, and cumulative dose of toxin. Five of the resistant patients had a significant titer of anti-botulinum toxin IgG antibodies, as determined by enzyme-linked immunosorbent assay (ELISA).

Inhalational poisoning by botulinum toxin and inhalation vaccination with its heavy-chain component.

Botulinum toxin is the etiologic agent responsible for the disease botulism, which is characterized by peripheral neuromuscular blockade. Botulism is ordinarily encountered as a form of oral poisoning. The toxin is absorbed from the lumen of the gut to reach the general circulation and is then distributed to peripheral cholinergic nerve endings.

Botulinum toxin type B for treatment of spasmodic dysphonia: a case report.

Although treatment with botulinum toxin type A (BTXA) has become the standard of care for most patients with laryngeal dystonia, its use is limited by the development of resistance to the toxin in some patients. Botulinum toxin type B (BTXB) has been found to be safe and effective in the treatment of cervical dystonia, but it has not been used previously to treat spasmodic dysphonia. Our experience with BTXB in a patient who developed resistance to BTXA suggests that BTXB may be safe and effective for the treatment of laryngeal dystonia, as well.

Establishment and use of a cell line expressing HSV-1 thymidine kinase to characterize viral thymidine kinase-dependent drug-resistance.

To understand the mechanisms of antiviral drug resistance and to have a system to examine the cytotoxicity of herpes simplex virus type 1 (HSV-1) inhibitors that are thymidine kinase (TK)-dependent, we have constructed a plasmid pFTK1 by inserting a DNA fragment containing the TK gene of HSV-1 strain F into the eukaryotic expression vector pcDNA3.1/His A. TK-deficient 143B cells were transfected with this vector and neomycin-resistant cells were selected.