Induction of immunity with avirulent Listeria monocytogenes 19113 depends on bacterial replication

Abstract

Events necessary for triggering the cell-mediated response to intracellular parasites are poorly understood. Here we show that extremely high doses of avirulent Listeria monocytogenes 19113 (>109) induce a modest and short-lived state of resistance in BALB/c mice. Induction of this protective state could not be achieved with nonviable bacteria and was blocked by inhibiting replication of viable L. monocytogenes 19113 through antibiotic treatment. The immune response was antigen specific and could be adoptively transferred with lymphoid cells. However, unlike the prototypic acquired cellular resistance induced by virulent Listeria strains, the protective response induced by L. monocytogenes 19113 was extremely short-lived, lasting less than 2 weeks, with a precipitous decline in the activity of the immune cells involved. An intervening in vitro culture period with concanavalin A greatly enhanced the activity of the adoptively transferred immune cells.

Lectin reactivity and virulence among strains of Listeria monocytogenes determined in vitro using the enterocyte-like cell line Caco-2

“…All lectin-unreactive strains proved to be avirulent, and all the strains behaving as virulent in vitro – which included all clinical isolates – showed the lectin-reactive phenotype. This phenotype, however, was also displayed by four nonhaemolytic strains and by a minority of haemolytic strains behaving as avirulent in vitro , including the well-known avirulent strain NCTC 5105 (Baldridge et al ., 1988; Pine et al ., 1991). This suggests that among Listeria isolates lectin reactivity is necessarily associated with, but insufficient for, pathogenicity.…”

“… ║ Carrying erm C-mediated, transferable erythromycin resistance (Roberts et al ., 1996). ❡ Avirulent strain (Baldridge et al ., 1988; Pine et al ., 1991). # Associated with a case of meningitis (Anonymous, 1986).…”

Naturally occurring virulence-attenuated isolates of Listeria monocytogenes capable of inducing long term protection against infection by virulent strains of homologous and heterologous serotypes

“…The question arises as to what these protective antigens might be. Numer-ous immunization studies performed previously with non-pathogenic Listeria have demonstrated their inability to generate long-lasting protection [13][14][15]. Also, mice infected with listeriolysinnegative strains do not acquire resistance because such bacteria are rapidly eliminated from the infected host even if repeated doses at regular intervals were administered to mice [16].…”

Skin manifestations and human immunodeficiency virus infection in the Tigray region, Ethiopia: Implications for clinical management and epidemiologic surveillance

“…[10][11][12][13]27 Skin disorders are also commonly seen in association with HIV infection, being diagnosed in more than 90% of infected patients during the course of the disease. [28][29][30][31] In Ethiopia, approximately 800,000 people living with HIV/ AIDS, with important implications for virus circulation. Skin manifestations may represent, in many cases, the alert sign of an underlying HIV infection and/or progression to AIDS and might thus help in formulating a diagnostic suspicion, particularly in resource-limited settings.…”