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Intravital excitation increases detection sensitivity for pulmonary tuberculosis by whole‐body imaging with β ‐lactamase reporter enzyme fluorescence
Author(s) -
Nooshabadi Fatemeh,
Yang HeeJeong,
Cheng Yunfeng,
Durkee Madeleine S.,
Xie Hexin,
Rao Jianghong,
Cirillo Jeffrey D.,
Maitland Kristen C.
Publication year - 2017
Publication title -
journal of biophotonics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.877
H-Index - 66
eISSN - 1864-0648
pISSN - 1864-063X
DOI - 10.1002/jbio.201600132
Subject(s) - mycobacterium tuberculosis , in vivo , fluorescence lifetime imaging microscopy , tuberculosis , fluorescence , fluorescence microscope , preclinical imaging , biology , microbiology and biotechnology , pathology , medicine , optics , physics
Tuberculosis is a pulmonary disease with an especially high mortality rate in immuno‐compromised populations, specifically children and HIV positive individuals. The causative agent, Mycobacterium tuberculosis ( Mtb ), is a very slow growing and difficult organism to work with, making both diagnosis and development of effective treatments cumbersome. We utilize a fiber‐optic fluorescence microendoscope integrated with a whole‐body imaging system for in vivo Mtb detection. The system exploits an endogenous enzyme of Mtb ( β ‐lactamase, or BlaC) using a BlaC‐specific NIR fluorogenic substrate. In the presence of BlaC, this substrate is cleaved and becomes fluorescent. Using intravital illumination of the lung to excite this probe, sensitivity of the optical system increases over trans‐ and epi‐illumination methods of whole‐body fluorescence imaging. We demonstrate that integration of these imaging technologies with BlaC‐specific fluorescent reporter probe improves the level of detection to ∼100 colony forming units, a 100× increase in sensitivity in comparison to epi‐illumination and a 10× increase in sensitivity in comparison to previous work in intravital excitation of tdTomato‐expressing Mtb . This lower detection threshold enables the study of early stage bacterial infections with clinical strains of Mtb and longitudinal studies of disease pathogenesis and therapeutic efficacy with multiple time points in a single animal.