19 Oct New Technology Can Quickly Detect TB and Evaluate Therapeutic Efficacy

MedicalResearch.com Interview with:

Dr. Ying Kong

Ying Kong Ph.D.
Assistant Professor
University of Tennessee Health Science Center
Department of Microbiology, Immunology, and Biochemistry
Memphis, TN 38163

MedicalResearch.com: What is the background for this study?

Response: Tuberculosis (TB) is a public health concern worldwide, with high morbidity and mortality. The causative agent of TB, M. tuberculosis, grows very slowly in culture. For research of TB, we need to quantitate bacterial numbers in order to evaluate drug and vaccine efficacy or to identify bacterial genes that are critical for survival in hosts or causing disease.

M. tuberculosis divides every ~20 hours, which is much slower than other bacteria such as E. coli and Salmonella typhimurium, which divide every 20 minutes. Conventionally, quantitation of M. tuberculosis needs to spread M. tuberculosis on agar plates and wait for four weeks to obtain visible colonies, and then to count colony forming units. For the fast-growing bacteria, it takes only 18 hours to obtain visible colonies on agar plates. We and other groups have developed fluorescent protein labeled M. tuberculosis strains in order to quantitate M. tuberculosis in real time by measuring fluorescence. In this way, we are able to estimate bacterial number right after fluorescence measurement, which only takes a few minutes. However, this technology is not a diagnostic tool for clinical use, because the M. tuberculosis strains that we used were recombinant strains transformed with fluorescent protein genes. Another imaging technology that we have developed, REF, is for diagnosis purpose, which has been described in details in our other papers (Xie H, et al. Rapid point-of-care detection of the tuberculosis pathogen using a BlaC-specific fluorogenic probe. Nat Chem. 2012 Oct;4(10):802-9. Cheng Y, et al. Fluorogenic probes with substitutions at the 2 and 7 positions of cephalosporin are highly BlaC-specific for rapid Mycobacterium tuberculosis detection. Angew Chem Int Ed Engl. 2014 Aug 25;53(35):9360-4.).

MedicalResearch.com: What are the main findings?

Response: We examined M. bovis BCG strains expressing various fluorescent proteins under two promoters: L5 and Hsp60, to select an optimal fluorescent protein and promoter to allow detection of mycobacteria in vitro and in vivo with fluorescence imaging. We found that the tdTomato expressing strain with a L5 promoter displayed the greatest fluorescence as compared to other fluorescent protein expressing strains. The L5-tdTomato strain demonstrated that it can be used to identify anti-TB therapeutic efficacy in a time-efficient way.

MedicalResearch.com: What should readers take away from your report?

Response: We now have a new technology to quickly quantitate M. tuberculosis in basic research and drug/vaccine development, which, once more widely applied, could significantly accelerate TB research, particular for analysis of novel therapies and during vaccine development.

MedicalResearch.com: What recommendations do you have for future research as a result of this study?

Response: It is promising to further improve threshold of detection of the current technology, as more and more near-infrared fluorescent proteins and dyes are emerging. On the other hand, the threshold of detection could be improved if the sensitivity of imaging equipment is enhanced.

MedicalResearch.com: Thank you for your contribution to the MedicalResearch.com community.

Citation:

Application of Fluorescent Protein Expressing Strains to Evaluation of Anti-Tuberculosis Therapeutic Efficacy In Vitro and In Vivo
Ying Kong , Dong Yang,Suat L. G. Cirillo,Shaoji Li,Ali Akin,Kevin P. Francis,Taylor Maloney,Jeffrey D. Cirillo
Published: March 2, 2016
http://dx.doi.org/10.1371/journal.pone.0149972

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Last Updated on October 19, 2016 by Marie Benz MD FAAD