Expression or possession of catalase gene does not alter the capacity of M. smegmatis to survive within human macrophages.
Mycobacterium tuberculosis genes are expressed and screened in Mycobacterium smegmatis as a host, hence their survival in human monocytes needs to be determined. Strains of Mycobacterium smegmatis with an inactive catalase-peroxidase gene (KatG), or into which the KatG gene of Mycobacterium tuberculosis had been transfected, were used to study the influence of catalase on intracellular mycobacterial survival within human monocyte-derived macrophages. The five strains of Mycobacterium smegmatis were observed to grow at similar rates, irrespective of their catalase phenotype, within IFNgamma-treated or untreated human macrophage cultures, over a 3 day infection period. Moreover, there was no differential pattern of growth or inhibition among the strains of Mycobacterium smegmatis studied.
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Department of Immunology, The University of Birmingham, Birmingham, UK,Burn and Shock Trauma Institute, Stritch School of Medicine, Loyola University Chicago, Maywood, Illinois, USA.