Acta Microbiologica 33. (1986)

3. szám - Salamah, A. A.–Charnetzky, W. T.: The Calcium Dependence Region of the 47 Megadalton Plasmid of Yersinia pestis is Required for Growth within Macrophages

Acta Microbiologica Hungarica 33 (3), pp. 213—219 (1986) THE CALCIUM DEPENDENCE REGION OF THE 47 MEGADALTON PLASMID OF YERSINIA PESTIS IS REQUIRED FOR GROWTH WITHIN MACROPHAGES A. A. Salamah and W. T. Charnetzky Department of Bacteriology and Public Health, Washington State University, Pullman, Washington, USA (Received July 12, 1985 Yersinia pestis cells bearing the 6,47 and 61 megadalton (Mdal) plasmids have been shown previously to be more resistant to novobiocin and to take up less gentian violet than cells lacking tbe 47 Mdal plasmid. Mutants with lesions in the calcium dependence region of the 47 Mdal plasmid, which are known to have resistance to high levels of novobiocin, were found to have rates of gentian violet and deoxycholate sensitivities identical to cells with intact plas­mids. Cells bearing the 6, 47 and 61 Mdal plasmids, but not cells without the 47 Mdal plasmid, were known to grow within peritoneal macrophages. Cells with mutations in the calcium depen­dence region of the 47 Mdal plasmid had greatly reduced virulence in iron compromised mice and were unable to proliferate in the peritoneal macrophages of these mice. Cells lacking both the 6 and 61 Mdal plasmids, selected in the presence of gentian violet, were found to have reduced gentian violet uptake but unexpectedly had increased sensitivity to novobiocin and deoxy­cholate. These cells had an LD50 in iron compromised mice similar to that of cells with all three plasmids and proliferated in the peritoneal macrophages of iron compromised mice. Virulent isolates of Yersinia pestis require Ca + + for prolonged growth at 37 °C [1, 2] and upon culturing on a medium lacking Ca++ yield avirulent, calcium independent mutants [3]. Burrows et al. [4] noted that aeration at 37 °C in highly enriched medium favours the production of V and W antigens by the calcium dependent, but not calcium independent strains. Calcium in­dependent isolates which still produce the V and W antigens, however, have been isolated [5]. Other virulence determinants, including the fraction 1 anti­gen, pesticin I, pigmentation, and the ability to synthesize purines de novo are independent of calcium dependence [6]. Calcium dependence correlates with the presence of a 47 megadalton (Mdal) plasmid [7, 8] and more specifically with a limited, but not precisely defined, region of this plasmid [9]. The 47 Mdal plasmid has been associated with the ability to grow within mouse peritoneal macrophages [10. 11], with a change in the LPS of cells grown at 37 °C [12], and with increased resistance to novobiocin and reduced rates of gentian violet uptake [13]. Ali A. Salamah Botany Department, College of Science, King Saud University P. O. B. 2455, Riyadh 11451, Saudi Arabia Willard T. Charnetzky Department of Biological Sciences, Florida Atlantic University Boca Taton, Florida 33431, USA Acta Microbiologica Hungarica 33, 1986 Akadémiai Kiadó, Budapest

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