Growth of Yersinia Pseudotuberculosis in Mouse Spleen Despite Loss of a Virulence Plasmid of Mol. WT 47 x 106

• Published in: Journal of medical microbiology Vol. 18; no. 3; pp. 371 - 375
• Main Authors: Simonet, M, Mazigh, D, Berche, P
• Format: Journal Article
• Language: English
• Published: Soc General Microbiol 01.12.1984
• ISSN: 0022-2615; 1473-5644
• DOI: 10.1099/00222615-18-3-371

Laboratoire de Microbiologie, Faculté de Médecine Necker-Enfants Malades, 75730 Paris * Unité d'Ecologie Bactérienne, Centre National des Yersinia, Institut Pasteur, 75724 Paris Cedex 15, France Received March 12, 1984 Accepted April 30, 1984 A highly virulent strain of Yersinia pseudotuberculosis (LD50 c. 10 2 bacteria/mouse) harboured two plasmids with mol. wt of 47 x 10 6 and 61 x 10 6 . The role of these plasmids in virulence was studied in mice with derived strains cured of plasmids. It was confirmed that the plasmid of mol. wt 47 x 10 6 played a major function in virulence. This was shown both by the increase of the LD50 and the lower rate of multiplication in the spleen obtained with strains cured of the plasmid of mol. wt 47 x 10 6 . The plasmid of mol. wt 61 x 10 6 did not play any role in virulence. This work also demonstrates that the strain cured of the plasmid of mol. wt 47 x 10 6 and the plasmid-free strain were able to multiply in the spleens of infected mice during a 7-day period. This suggests that virulence factors not associated with plasmids are also responsible for the bacterial growth in tissues in vivo .