Bacterial thymidine kinase as a non-invasive imaging reporter for Mycobacterium tuberculosis in live animals.
BACKGROUND
Bacteria can be selectively imaged in experimentally-infected animals using exogenously administered 1-(2'deoxy-2'-fluoro-beta-D-arabinofuranosyl)-5-[(125)I]-iodouracil ([(125)I]-FIAU), a nucleoside analog substrate for bacterial thymidine kinase (TK). Our goal was to use this reporter and develop non-invasive methods to detect and localize Mycobacterium tuberculosis.


RESULTS
We engineered a M. tuberculosis strain with chromosomally integrated bacterial TK under the control of hsp60 -- a strong constitutive mycobacterial promoter. [(125)I]FIAU uptake, antimicrobial susceptibilities and in vivo growth characteristics were evaluated for this strain. Using single photon emission computed tomography (SPECT), M. tuberculosis P(hsp60) TK strain was evaluated in experimentally-infected BALB/c and C3HeB/FeJ mice using the thigh inoculation or low-dose aerosol infection models. M. tuberculosis P(hsp60) TK strain actively accumulated [(125)I]FIAU in vitro. Growth characteristics of the TK strain and susceptibility to common anti-tuberculous drugs were similar to the wild-type parent strain. M. tuberculosis P(hsp60) TK strain was stable in vivo and SPECT imaging could detect and localize this strain in both animal models tested.


CONCLUSIONS
We have developed a novel tool for non-invasive assessment of M. tuberculosis in live experimentally-infected animals. This tool will allow real-time pathogenesis studies in animal models of TB and has the potential to simplify preclinical studies and accelerate TB research.
Davis
Stephanie L
SL
Center for Tuberculosis Research, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
Be
Nicholas A
NA
Lamichhane
Gyanu
G
Nimmagadda
Sridhar
S
Pomper
Martin G
MG
Bishai
William R
WR
Jain
Sanjay K
SK
D000818:Animals; D001086:Arabinofuranosyluracil / Q000008:administration & dosage / Q000031:analogs & derivatives; D002876:Chromosomes, Bacterial; D005260:Female; D007457:Iodine Radioisotopes / Q000008:administration & dosage; D051379:Mice; D008807:Mice, Inbred BALB C; D008809:Mice, Inbred C3H; D008826:Microbial Sensitivity Tests; D009169:Mycobacterium tuberculosis / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D011401:Promoter Regions, Genetic; D013937:Thymidine Kinase / Q000378:metabolism*
D007457:Iodine Radioisotopes; D001086:Arabinofuranosyluracil; C043457:fialuridine; D013937:Thymidine Kinase