DEVELOPMENT OF L PHASE VARIANTS OF NEISSERIA MENINGITIDIS AND THEIR PATHOGENICITY IN MICE.
Annual rept. no. 6, 1 Oct 69-30 Sep 70.
CHICAGO UNIV ILL
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Work has continued on the development and characteristics of L forms of Neisseria meningitidis with particular emphasis on their stabilization. To date, 15 strains representing serotypes A, B, C, Boshard and RAS, including 3 streptomycin-resistant isolates, have stabilized. Of a variety of methods tried to accelerate the transition from unstable to stable L forms, the isolation of SMr mutants from reverted L form growth shows the most promise. Most Lr form strains that required 40 transfers to stabilize, reverted to diplococcal growth after subcultivation in the absence of penicillin andor following intraperitoneal inoculation into mice. Eight stable L form strains readily adapted to growth in simple liquid media by serial subcultivation in decreasing concentrations of agar, sucrose, and horse serum. One broth adapted strain thus far tested in mice caused a higher mortality than the same stable L form which had not been adapted to multiplication in a liquid environment. Classic deoxyribonucleate transformation to streptomycin resistance andor to L form growth was demonstrated in serotypes A, B, and C using heat killed broth cultures of a variety of stable L form strains. Transformation with a phenol extract of DNA from one stable L form strain resulted in numbers of SMr and L form transformants comparable to those obtained with broth cultures. Transformation did not occur in the presence of DNAse. Author