This proposal addresses the need for a simple, sensitive screening test for the early detection and differentiation of Mycobacterium species in sputum specimens. The proposed diagnostic test will combine gene probes specific to mycobacterial ribosomal RNA (16S rRNA) with a proprietary integrated optic interferometer. Hybridization of rRNA to an oligonucleotide probe attached to the interferometer surface results in a refractive index change that can be quantified by the interferometer. Identification of Mycobacterium species is achieved by using short DNA probes of specific complementary sequences. By using a supplementary sandwich assay, this diagnostic test may enable Mycobacterium identification without the need for nucleic acid amplification techniques such as PCR. An optical sensor based on this approach has several key advantages: 1) it allows simultaneous determination of multiple species, 2) it is sensitive (potentially << 10/4 cells/mL), 3) it is rapid (< 15 minutes), 4) it is simple (no wash steps or subjective interpretation), and 5) it is low cost (< $5 per test, no expensive analytic instrumentation). Further, the integrated format will allow packaging as a hand-held device, applicable to third-world screening of patients for putative mycobacterial disease.Proposed commercial application:Mycobacterium infections, and tuberculosis in particular, are a major cause of infectious disease- related death on a worldwide scale. By 1997, the tuberculosis market in the US alone will be $75 to $100 million. Conventional methods for identification of the causative organism are slow, and lead to high treatment costs and patient suffering. The proposed optical sensor would enable early diagnosis through increased sensitivity combined with simultaneous multispecies identification.National Institute of Allergy and Infectious Diseases (NIAID)
