Comparative Aspects of Ricin Toxicity by Inhalation.

The pathogenesis of ricin toxicity following inhalation has been investigated in many animal models, including the non-human primate (predominantly the rhesus macaque), pig, rabbit and rodent. The toxicity and associated pathology described in animal models are broadly similar, but variation appears to exist. This paper reviews the published literature and some of our own unpublished data and describes some of the possible reasons for this variation. Methodological variation is evident, including method of exposure, breathing parameters during exposure, aerosol characteristics, sampling protocols, ricin cultivar, purity and challenge dose and study duration. The model species and strain used represent other significant sources of variation, including differences in macro- and microscopic anatomy, cell biology and function, and immunology. Chronic pathology of ricin toxicity by inhalation, associated with sublethal challenge or lethal challenge and treatment with medical countermeasures, has received less attention in the literature. Fibrosis may follow acute lung injury in survivors. There are advantages and disadvantages to the different models of pulmonary fibrosis. To understand their potential clinical significance, these factors need to be considered when choosing a model for chronic ricin toxicity by inhalation, including species and strain susceptibility to fibrosis, time it takes for fibrosis to develop, the nature of the fibrosis (e.g., self-limiting, progressive, persistent or resolving) and ensuring that the analysis truly represents fibrosis. Understanding the variables and comparative aspects of acute and chronic ricin toxicity by inhalation is important to enable meaningful comparison of results from different studies, and for the investigation of medical countermeasures.

A liposome-based cancer vaccine for a rapid and high-titre anti-ErbB-2 antibody response.

Vaccines are arguably the most important medical technology developed to date. However, effective treatment of diseases such as breast cancer have so far evaded standard vaccination strategies. One popular target for cancer treatment is the cell surface membrane protein, ErbB-2, also known as Her-2 or neu. It is localised to the cell surface and has raised expression in 15-30% of all breast cancers, as well as in ovarian, colon and lung cancer. Here, a liposomal system comprised of spatially separated ErbB-2 peptide, to activate B cells, and ovalbumin peptide OVA323-339, to provide non-cognate T cell support, was used to generate antibodies against the epitope of the ErbB-2 protein targeted by Pertuzumab, a monoclonal antibody licensed for the treatment of ErbB-2 expressing cancers. After just 7 days a raised (7.3-fold, p<0.01), isotype-switched, humoral immune response specific for the ErbB-2 peptide was achieved in mice with pre-existing immunity to OVA which were exposed to liposomes with external ErbB-2 and internal OVA323-339. The absence of pre-existing OVA immunity in the mice or OVA323-339 peptide in the liposomes removed the effect. The effect of this anti-ErbB-2 antibody response was characterised against an ErbB-2 overexpressing tumour cell line both in vitro and in vivo. Notably, antibody responses were demonstrated to induce cell death in vitro, resulting in 96% reduction in viable cells. This study, therefore, demonstrates the feasibility of this approach to generate a rapid, high-titre, isotype-switched, antibody response that specifically targets ErbB-2 overexpression on tumour cells and is capable of inducing cell death in vitro in the absence of complement or immune cells.

Direct Detection and Discrimination of Nucleotide Polymorphisms Using Anthraquinone Labeled DNA Probes.

A novel electrochemical detection approach using DNA probes labeled with Anthraquinone (AQ) as a reporter moiety has been successfully exploited as a method for the direct detection of DNA targets. This assay uses simple voltammetry techniques (Differential Pulse Voltammetry) to exploit the unique responsiveness of AQ to its chemical environments within oxygenated aqueous buffers, providing a specific detection mechanism as a result of DNA hybridization. This measurement is based on a cathodic shift of the reduction potential of the AQ tag and the concurrent reduction in peak current upon DNA binding. The further utility of this approach for discrimination of closely related DNA targets is demonstrated using DNA strands specific to B. anthracis and closely related bacillus species. DNA targets were designed to the rpoB gene incorporating nucleotide polymorphisms associated with different bacillus species. This assay was used to demonstrate that the shift in reduction potential is directly related to the homology of the target DNA. The discriminatory mechanism is dependent on the presence of oxygen in the measurement buffer and is strongly linked to the position of the nucleotide polymorphisms; with homology at the terminus carrying the AQ functionalised nucleotide critical to achieving accurate discrimination. This understanding of assay design was used to demonstrate an optimized assay capable of discriminating between Yersinia pestis (the causative agent of plague) and closely related species based on the groEL gene. This method is attractive as it can not only detect DNA binding, but can also discriminate between multiple Single Nucleotide Polymorphisms (SNPs) within that DNA without the need for any additional reagents, reporters, or processes such as melting of DNA strands. This indicates that this approach may have great potential to be exploited within novel biosensors for detection and diagnosis of infectious disease in future Point of Care (PoC) devices.

Evaluation of a novel electrochemical detection method for Chlamydia trachomatis: application for point-of-care diagnostics.

Atlas Genetics has developed a point-of-care device for Chlamydia trachomatis utilizing a novel electrochemical detection principle. The assay has a time-to-result of less than 25 min. An independent preclinical validation study using 306 pretyped clinical samples determined a clinical sensitivity of 98.1% and specificity of 98.0%.