Two long-tailed and two short-tailed bacteriophages are spontaneously released from the Salmonella johannesburg 7.58(R+) strain, and could be propagated on the susceptible strain 5.58(R-). The two long-tailed phages could be distinguished by their tail morphology, and are not adsorbed on a column of sepharose coupled to LPS (R-). The two short-tailed particles (group C of Bradley, group C1 of Ackermann) are converting phages. They are thermostable, are adsorbed on a column of sepharose-LPS, and possess an endo-glycosidase activity leading to the cleavage of the LPS of the sensitive strain. However, one of these short-tailed phages, termed phi 1(40), is a temperate phage producing small and turbid plaques, although the other one, termed phi 1(40)vir, is a virulent phage producing large and clear plaques. A polysaccharidic antigen could be coupled to these phages but the corresponding antiserum was unable to inactivate the modified bacteriophages.

Bacteriophages↗

PubMedDate not supplied

Interaction of lipopolysaccharides with cells of immunological interest.

Recent progress has been made in understanding the diverse effects of bacterial endotoxin (LPS) on animal systems. Experiments from our laboratory, as well as those from several other groups, have provided strong evidence supporting the presence of different sites of interaction with LPS in cells of immunological interest. However, the sequence of expression of receptors, and their interrelations, are poorly understood. In this review, we summarize the essentials of these studies, with particular emphasis on experiments from our own laboratory. Our results suggest that the "positive" signals which trigger the activation of B lymphocytes and bone-marrow cells, as well as the "negative" signals which trigger macrophage desensitization and tolerance to LPS, might be delivered by sparsely represented and yet unidentified LPS receptors. The identification of these molecules would clarify the mechanisms involved in the immunostimulatory as well as in the pathophysiological effects of endotoxin, and should have significant impact upon potential therapeutic intervention in endotoxin-mediated disease.

Animals↗