A Simple Adult-Mouse Test for Tissue Invasiveness in Yersinia Enterocolitica Strains of Low Experimental Virulence

Abstract

SUMMARY. The virulence of Yersinia enterocolitica depends on the presence of a 70-kilobase plasmid, called the Vwa plasmid. This situation is particularly favourable for studies of the mechanism of pathogenicity, but these are hindered by the lack of a suitable animal test to monitor the virulence of the human-pathogenic strains isolated outside the USA which belong to serogroups 0:3, 0:9 and 0:5,27. We observed that, after oral administration to the mouse, the Vwa-positive strains of these serogroups produce a discrete systemic infection while the Vwa-negative strains do not. We present here a simple mouse-virulence test based on this observation.

The Replication, Partition and yop Regulation of the pYV Plasmids Are Highly Conserved in Yersinia enterocolitica and Y. pseudotuberculosis

“…enterocolitica Plasmid mini-vir-kan (1 1.7 kb) consisted of BamHI fragment 3 (hereafter referred to as B3) from pYVe439-80, linked to the kanamycin (Km) resistance determinant of Tn5 (Bakour et al, 1983). Mini-vir-kan was further reduced in size by BstEII digestion, ligation and transformation of E. coli C600.…”

“…Stabilization of p YVe439-80 Like other low-copy-number plasmids, pYVe439-80 is very stably inherited at low temperature (Bakour et al, 1983). In contrast, the mini-derivatives of pYVe439-80 are lost at 28°C at a rate of about 10% in 25-30 generations, suggesting that a partitioning system (Nordstrom et al, 1980) was lost during the process of reduction.…”

“…The functions of uirA, B and C are not yet known (Cornelis et al, 1986(Cornelis et al, , 1987a. The region controlling the calcium response is highly conserved in the pYV plasmids from Y. enterocolitica, Y. pseudotuberculosis and Y. pestis (Goguen et The replication functions are also located differently in the pYV plasmid from Y. enterocolitica (Bakour et al, 1983 ;Portnoy et al, 1984) as compared with the pYV plasmids from Y. pseudotuberculosis and Y. pestis (Portnoy & Falkow, 1981 ;Portnoy et al, 1984). Portnoy et al (1984) suggested that the replication functions might be different in these two types and that a recombinational event had occurred between two ancestral plasmids, one encompassing the replication region and another encompassing the calcium-dependence region.…”

“…The only determinant they have in common with F is incD. This determinant could be part of a partition system analogous to that of F (Bakour et al, 1983). The present work is mainly devoted to the ancillary functions of pYV, namely replication and partition.…”

“…The three species carry plasmids of about 70 kb that appear to be necessary for virulence (Gemski et al, 1980a, 6 ;Zink et al, 1980;Ferber & Brubaker, 1981 ;Bakour et al, 1985). These plasmids, generally called pYV plasmids, cause a requirement for calcium for growth at 37 "C : pYV-containing yersiniae form colonies at 28 "C but not at 37 "C on media deprived of calcium, while bacteria cured of pYV plasmids or carrying a mutated plasmid grow at both temperatures on oxalated media (see Cornelis et al, 19876).…”