Bacterial thymidine kinase as a non-invasive imaging reporter for Mycobacterium tuberculosis in live animals

PLoS One. 2009 Jul 16;4(7):e6297. doi: 10.1371/journal.pone.0006297.


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.

Methodology/principal findings: 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.

Conclusion: 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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Arabinofuranosyluracil / administration & dosage
  • Arabinofuranosyluracil / analogs & derivatives
  • Chromosomes, Bacterial
  • Female
  • Iodine Radioisotopes / administration & dosage
  • Mice
  • Mice, Inbred BALB C
  • Mice, Inbred C3H
  • Microbial Sensitivity Tests
  • Mycobacterium tuberculosis / drug effects
  • Mycobacterium tuberculosis / enzymology*
  • Mycobacterium tuberculosis / genetics
  • Mycobacterium tuberculosis / growth & development
  • Promoter Regions, Genetic
  • Thymidine Kinase / metabolism*


  • Iodine Radioisotopes
  • Arabinofuranosyluracil
  • fialuridine
  • Thymidine Kinase