No abstract

Development of an effective vaccine against

Bacterial and viral upper respiratory infections (URI) produce highly variable clinical symptoms that cannot be used to identify the etiologic agent. Proper treatment, however, depends on correct identification of the pathogen involved as antibiotics provide little or no benefit with viral infections. Here we describe a rapid and sensitive genotyping assay and microarray for URI identification using standard amplification and hybridization techniques, with electrochemical detection (ECD) on a semiconductor-based oligonucleotide microarray. The assay was developed to detect four bacterial pathogens (Bordetella pertussis, Streptococcus pyogenes, Chlamydia pneumoniae and Mycoplasma pneumoniae) and 9 viral pathogens (adenovirus 4, coronavirus OC43, 229E and HK, influenza A and B, parainfluinza types 1, 2, and 3 and respiratory syncytial virus. This new platform forms the basis for a fully automated diagnostics system that is very flexible and can be customized to suit different or additional pathogens. Multiple probes on a flexible platform allow one to test probes empirically and then select highly reactive probes for further iterative evaluation. Because ECD uses an enzymatic reaction to create electrical signals that can be read directly from the array, there is no need for image analysis or for expensive and delicate optical scanning equipment. We show assay sensitivity and specificity that are excellent for a multiplexed format.

Exposure of the mouse oral cavity to Porphyromonas gingivalis results in the development of gingivitis and periapical bone loss, which apparently are associated with a Th1 response to bacterial antigens. We have used this infection model in conjunction with direct T-cell expression cloning to identify bacterial antigens that induce a preferential or biased T helper response during the infectious process. A P. gingivalis-specific CD4 T-cell line derived from mice at 3 weeks postchallenge was used to directly screen a P. gingivalis genomic expression library. This screen resulted in the identification of five genes coding for previously identified proteins and three other putative protein antigens. One of the identified proteins, P. gingivalis thiol peroxidase, was studied in detail because this molecule belongs to a protein family that is apparently involved in microbial pathogenesis. Infection of mice with P. gingivalis, either via the subcutaneous route or after exposure of the animal's oral cavity to viable bacteria, resulted in the induction of a strong thiol peroxidase-specific immune response characterized by the production of high titers of specific serum immunoglobulin G2a antibody and the production of gamma interferon by antigen-stimulated lymphoid cells, a typical Th1-biased response. Thus, the use of a proven T-cell expression cloning approach and a mouse model of periodontal disease resulted in the identification and characterization of P. gingivalis proteins that might be involved in pathogenesis.

The epidermal growth factor receptors, EGFR (erbB-1) and HER2 (erbB-2), and their down stream signaling events promote tumor growth and survival in a variety of epithelial tumors. Current treatment strategies used to target these receptors include mAbs directed against their extracellular domains and small molecule inhibitors of their tyrosine kinase activities. The efficacy of these types of therapeutics is increasingly being found to be contingent on the genotype of the targeted cancer. In vitro evaluation of mAbs is reliant on selection of tumor cell lines driven by the specific antigen proteins of interest and their associated pathways. We selected a panel of eight human tumor cell lines, six breast cancer (BT474, SK-BR-3, MDA-MB-453, MDA-MB-231, MDA-MB-468 and MCF-7), one colon (SW48) and one skin (A431) with varying levels of HER2, EGFR and EGFR/HER2 expression to evaluate the mAbs cetuximab and trastuzumab for antiproliferative effects, ability to induce apoptosis and the ability to block cell cycle. These findings were compared to results obtained after treatment with lapatinib, erlotinib, Ly294002 and Tamoxifen. The BT474 and SK-BR-3 breast cancer cell lines with HER2 amplified expression demonstrated cytostatic antiproliferative and G1/S cell cycle block sensitivity to the anti-HER2 antibody trastuzumab. The more prominent inhibitory effects observed in the BT474 cell line were further confirmed by measurable induced decreased levels of phospho-Akt and increased levels of the CDK2 inhibitor p27Kip1 following treatment with trastuzumab, lapatinib and Ly294002. The SW48 colon and A431 skin cancer cell lines with EGFR mutations and EGFR over expression, respectively, demonstrated cytostatic antiproliferative sensitivity to the anti-EGFR antibody cetuximab. This in vitro cell-based multiplexed approach for assessment of oncology therapeutics based on genetically directed cell line selection, demarcation of cytostatic and cytotoxic cell proliferation inhibition and assessment of receptor down stream signaling biomarkers offers greater predictive efficacious value and can be used to identify optimal candidates for combination therapies. Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P6-14-17.