Brooks L, Mahenthiralingam E, Stokes RW; American Society for Microbiology. General Meeting.

Abstr Gen Meet Am Soc Microbiol. 1997 May 4-8; 97: 559 (abstract no. U92).

University of British Columbia, Vancouver, Canada.

Mycobacterium intracellulare, a member of the Mycobacterium avium complex (MAC), is being used to study the molecular factors and gene regulation involved in virulence. In this model virulence is assessed by the survival characteristics of the organisms in BALB/c mice i.e. a virulent M. intracellulare, Trudeau mycobacterial collection (TMC) #D763, grows progressively in the target organs of BALB/c mice whilst an avirulent M. intracellulare strain, TMC #1403, is eliminated. The aim of the project is to isolate an avirulent derivative of the virulent D673 M. intracellulare strain and to investigate the genetic determinants of this alteration. Wild type M. intracellulare D673 was mutagenised using the chemical mutagen N-methyl-N-Nitro-N-Nitrosoguanidine (NTG). As the colonies of the avirulent 1403 isolate of M. intracellulare have a distinct smooth domed morphology NTG treated D673 cells were screened for altered colony morphology. Two NTG-mutagenised derivatives were isolated, one with a flat matt colony morphology (D673FM) and one with a smooth domed morphology (D673SmD1). Random amplified polymorphic DNA (RAPD) analysis of each mutant demonstrated that they were both derived from M. intracellulare D673. Both mutants maintain their altered morphology on solid agar and in liquid culture, exhibit increased susceptibility to antibiotics and, following electroporation, demonstrate increased rates of transformation. The mutants have been investigated in our mouse model; D673SmD1 was found to be avirulent, whilst D673FM retained its virulence. Both mutants retained their phenotypes and RAPD profiles following passage through the mouse. The avirulent D673SmD1 has been transformed with a wild type D673 genomic cosmid library and transformants are currently being screened for complementation in order to investigate the genetic alterations in D673SmD1 responsible for the avirulence of the mutant.

Publication Types:

• Meeting Abstracts

Keywords:

• Animals
• Anti-Bacterial Agents
• Mice
• Mice, Inbred BALB C
• Mice, Inbred C57BL
• Mice, Inbred DBA
• Muridae
• Mycobacterium avium Complex
• Mycobacterium avium-intracellulare Infection
• Virulence
• pathogenicity

Other ID:

• 98928848

UI: 102235501

From Meeting Abstracts