Determination of virulence of different strains of Listeria monocytogenes and Listeria innocua by oral inoculation of pregnant mice

Abstract

A pregnant mouse model was developed to follow the course of infection after peroral inoculation with six different strains of Listeria monocytogenes and one strain of Listeria innocua. Tissues were sampled and analyzed by microbiologic and histologic methods for 5 days postinoculation. In gnotobiotic pregnant BALB/c mice, L. monocytogenes Scott A (SA), serotype 4b, colonized the gastrointestinal tract, translocated to the livers and spleens of mice by day 1 postinoculation, and multiplied in these tissues until day 4. Infection of the placental tissues occurred by days 3 and 4 and was followed by infection of the fetuses. Little damage of colonic and cecal tissues was evident by histologic examination. Livers and spleens showed a cellular immune response; a similar immune response was not detected in the placentas or fetuses. A rough variant of L. monocytogenes SA which was as virulent as the parent strain in mice when injected intraperitoneally was less virulent perorally and did not consistently infect the fetuses. L. monocytogenes ATCC 19113, serotype 3a, did not colonize the gastrointet tract, nor was it isolatted fom any internal tssue. L. monocyn es -strains of serotpes 1/2a and 1/2b behaved like the SA strain in this mouse model. L. innocua colonized the gastrointestinal tract and translocated to the livers and spleens but did not survive in these organs and rapidly disappeared without infecting placental and fetal tissues. In comparison with gnotobiotic mice, conventional pregnant mice inoculated with L. monocytogenes strains showed less consistent infection. These results suggest that the gnotobiotic pregnant mouse is a useful model for detecting differences in virulence relating to colonization, invasiveness, and uteroplacental infection which cannot be detected by intraperitoneal inoculation of mice.

Experimental Infection in Mice with Bacillus licheniformis

“…Murine models are useful for the study of several bovine infectious diseases such as, for example, brucellosis (TOBIAS et al, 1993), listeriosis (LAMMERDING et al, 1992), paratuberculosis (CHIODINI and BUERGELT, 1993), and mycosis ( JENSEN and SCHQNHEYDER, 1993). Infections in cattle due to Bacillus licheniformis, a spore-forming facultatively anaerobic bacterium, occur world wide, but most aspects of the infection are unknown.…”

Treatment with the antigranulocyte monoclonal antibody RB6-8C5 impairs resistance of mice to gastrointestinal infection with Listeria monocytogenes

“…There have been relatively few experimental studies of the host response to gastrointestinal infection with L. monocytogenes. Although these have established the importance of cellular immunity, there is little information regarding the roles of specific cell populations and mediators (8,13,(15)(16)(17).…”

“…Previous reports from several laboratories, including our own, have established that the resistance of mice to gastrointestinal infection with L. monocytogenes is quite high (13,(15)(16)(17). As a result, in our first experiment, we chose to infect mice i.g.…”

Recombinant Listeria monocytogenes as a live vaccine vehicle and a probe for studying cell‐mediated immunity

“…which lack the virulence gene cluster of L. monocytogenes may offer an intriguing alternative approach (69). Several groups have succeeded in expressing L. monocytogenes virulence genes, such as prfA, plcA, hiy, and actA, in recombinant L. innocua (70)(71)(72)(73). Indeed, expression of hly conferred upon L. innocua the ability to escape phagosomes and replicate within the cytosol, while expression of pIcA allowed survival and growth in phagolysosomes (73.…”