Date of Award

Summer 8-18-2023

Level of Access Assigned by Author

Open-Access Thesis

Degree Name

Master of Science (MS)




Sally D. Molloy

Second Committee Member

Keith W. Hutchison

Third Committee Member

Joshua B. Kelley

Additional Committee Members

Melissa Maginnis


Prophage, integrated viral genomes, are known to increase antibiotic resistance of bacterial pathogens. Non-tuberculosis mycobacteria such as Mycobacterium abscessus, causes pulmonary and disseminating infections that are often totally drug resistant. Most M. abscessus isolates carry one or more prophages but their role in intrinsic antibiotic resistance is not yet known. We have demonstrated that M. chelonae, a close relative of M. abscessus, has higher antibiotic resistance and expression of a conserved mycobacterial regulator of antibiotic resistance genes, whiB7, increases in the presence of two prophage genomes. The first prophage, McProf, only carries out lysogenic infection of M. chelonae. The second prophage, BPs, is capable of lysogenic infection but also undergoes induction and lytic infection. We hypothesize that BPs induction activates McProf gene products, such as polymorphic toxin systems, to increase expression of whiB7. We have demonstrated that strictly lytic infections by BPs increases whiB7 expression in the presence of McProf. Inhibiting BPs induction by overexpression of the BPs immunity repressor in the M. chelonae double lysogen (BPs, McProf) decreases whiB7 expression relative to controls. To learn more about the fraction of cells in a population expressing whiB7 and undergoing induction, we created a green fluorescent protein (GFP) BPs fluorophage and performed fluorescent microscopy on four fluorescent whiB7 reporter strains carrying one (BPsGFP or McProf), two (BPsGFP, McProf) or zero prophages (ΔMcProf). The majority of cells in a double lysogen (BPsGFP, McProf) population are undergoing induction and have high whiB7 expression. Time lapse experiments will be done in the future to monitor induction events and whiB7 expression in double lysogens strains to learn the fate of cells undergoing BPs induction in the presence of McProf and if whiB7 expression occurs in induced cells or in neighboring cells.

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