Comparison of Bioluminescent Substrates in Natural Infection Models of Neglected Parasitic Diseases.

Abstract

The application of in vivo bioluminescent imaging in infectious disease research has significantly increased over the past years. The detection of transgenic parasites expressing wildtype firefly luciferase is however hampered by a relatively low and heterogeneous tissue penetrating capacity of emitted light. Solutions are sought by using codon-optimized red-shifted luciferases that yield higher expression levels and produce relatively more red or near-infrared light, or by using modified bioluminescent substrates with enhanced cell permeability and improved luminogenic or pharmacokinetic properties. In this study, the in vitro and in vivo efficacy of two modified bioluminescent substrates, CycLuc1 and AkaLumine-HCl, were compared with that of D-luciferin as a gold standard. Comparisons were made in experimental and insect-transmitted animal models of leishmaniasis (caused by intracellular Leishmania species) and African trypanosomiasis (caused by extracellular Trypanosoma species), using parasite strains expressing the red-shifted firefly luciferase PpyRE9. Although the luminogenic properties of AkaLumine-HCl and D-luciferin for in vitro parasite detection were comparable at equal substrate concentrations, AkaLumine-HCl proved to be unsuitable for in vivo infection follow-up due to high background signals in the liver. CycLuc1 presented a higher in vitro luminescence compared to the other substrates and proved to be highly efficacious in vivo, even at a 20-fold lower dose than D-luciferin. This efficacy was consistent across infections with the herein included intracellular and extracellular parasitic organisms. It can be concluded that CycLuc1 is an excellent and broadly applicable alternative for D-luciferin, requiring significantly lower doses for in vivo bioluminescent imaging in rodent models of leishmaniasis and African trypanosomiasis.

• Authors: Sarah Hendrickx, Dimitri Bulté, Dorien Mabille, Roxanne Mols, Mathieu Claes, Kayhan Ilbeigi, Rokaya Ahmad, Laura Dirkx, Sara I Van Acker, Guy Caljon
• Journal: International journal of molecular sciences (Int J Mol Sci) Vol. 23 Issue 24 (Dec 16 2022) ISSN: 1422-0067 [Electronic] Switzerland
• PMID: 36555716 (Publication Type: Journal Article)

Chemical References

• Luciferases, Firefly
• Luciferases
• Luciferins
• Firefly Luciferin

Topics

• Animals
• Luciferases, Firefly (genetics, metabolism)
• Trypanosomiasis, African
• Parasites (metabolism)
• Luminescent Measurements (methods)
• Luciferases (genetics, metabolism)
• Luciferins
• Firefly Luciferin (metabolism)