| Summary: | 碩士 === 慈濟大學 === 醫學檢驗生物技術學系醫學生物技術碩士班 === 102 === Tuberculosis is an infectious disease which caused by Mycobacterium
tuberculosis. Effective therapies existed are limited by the emergence of multidrug-
resistant tuberculosis (MDR-TB) and extensively drug resistant tuberculosis
(XDR-TB). Effective therapeutic regimens exist that are limited by the emergence of
the inability of antibiotics to kill dormant organisms. Previous studies pointed out that
endolysins produced from well assembled phage can hydrolyze the peptidoglycan of
cell wall. We have discovered a Mycobacterium smegmatis bacteriophage which
genome size of this phage is 46Kb by full genome sequencing and 72 open reading
frames were predicted. We selected two suspected endolysin genes named lysA and
lysB, cloned into E.coli and expressed, purified the protein to analyze their effect of
bactericidal assay. The bactericidal test result showed that LysA and LysB could
effectively restrain smegmatis. Under the Scanning Electron Microscope, it was
observed that LysA and LysB could directly destroy smegmatis. The cytotoxicity
effect of LysA and LysB was determined in HaCaT cell lines by WST-1 assay in vitro,
there is no difference was found between negative control. Intracellular bactericidal
activity assay showed that treatment of M. smegmatis–infected, RAW 264.7
macrophage, with LysA or LysB, resulted in a significant reduction in the number of
viable intracellular bacilli. These results indicate that BTCU-1 and its cloned
biologically active lytic modules have antimycobacterial activity, and suggest that
they are good candidates for a therapeutic/disinfectant agent to control mycobacterial
infections.
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