Deficiency of double-strand DNA break repair does not impair Mycobacterium tuberculosis virulence in multiple animal models of infection.
Mycobacterium tuberculosis persistence within its human host requires mechanisms to resist the effector molecules of host immunity, which exert their bactericidal effects through damaging pathogen proteins, membranes, and DNA. Substantial evidence indicates that bacterial pathogens, including M. tuberculosis, require DNA repair systems to repair the DNA damage inflicted by the host during infection, but the role of double-strand DNA break (DSB) repair systems is unclear. Double-strand DNA breaks are the most cytotoxic form of DNA damage and must be repaired for chromosome replication to proceed. M. tuberculosis elaborates three genetically distinct DSB repair systems: homologous recombination (HR), nonhomologous end joining (NHEJ), and single-strand annealing (SSA). NHEJ, which repairs DSBs in quiescent cells, may be particularly relevant to M. tuberculosis latency. However, very little information is available about the phenotype of DSB repair-deficient M. tuberculosis in animal models of infection. Here we tested M. tuberculosis strains lacking NHEJ (a Δku ΔligD strain), HR (a ΔrecA strain), or both (a ΔrecA Δku strain) in C57BL/6J mice, C3HeB/FeJ mice, guinea pigs, and a mouse hollow-fiber model of infection. We found no difference in bacterial load, histopathology, or host mortality between wild-type and DSB repair mutant strains in any model of infection. These results suggest that the animal models tested do not inflict DSBs on the mycobacterial chromosome, that other repair pathways can compensate for the loss of NHEJ and HR, or that DSB repair is not required for M. tuberculosis pathogenesis.
Immunology Program, Sloan Kettering Institute, New York, New York, USA.
Brook E
BE
Heaton
Division of Infectious Diseases, Memorial Sloan Kettering Cancer Center, New York, New York, USA.
Daniel
D
Barkan
Immunology Program, Sloan Kettering Institute, New York, New York, USA.
Paola
P
Bongiorno
Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
Petros C
PC
Karakousis
Immunology Program, Sloan Kettering Institute, New York, New York, USA Division of Infectious Diseases, Memorial Sloan Kettering Cancer Center, New York, New York, USA glickmam@mskcc.org.
Michael S
http://orcid.org/0000-0001-7918-5164
MS
Glickman
D000818:Animals; D058491:Bacterial Load; D053903:DNA Breaks, Double-Stranded; D004260:DNA Repair; D045643:DNA Repair Enzymes / Q000172:deficiency*; D004195:Disease Models, Animal; D005260:Female; D017353:Gene Deletion; D006168:Guinea Pigs; D006651:Histocytochemistry; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D009169:Mycobacterium tuberculosis / Q000201:enzymology* / Q000472:pathogenicity*; D016019:Survival Analysis; D014376:Tuberculosis / Q000276:immunology* / Q000382:microbiology* / Q000473:pathology; D014774:Virulence
D045643:DNA Repair Enzymes