Extraction and partial characterization of a leukotoxin from a plaque-derived Gram-negative microorganism

Abstract

The plaque-derived gram-negative microorganism Y4 identified as a member of the genus Actinobacillus, was tested for a soluble cytotoxic factor(s). Sonication or incubation of viable Y4 microorganisms in distilled water or normal human serum resulted in liberation of a soluble material which was cytotoxic in vitro for human polymorphonuclear leukocytes (PMNs). The Y4 soluble sonic extract was also cytotoxic to human peripheral blood monocytes. However, human lymphocytes, platelets, and fibroblasts, as well as rabbit, rat, and mouse leukocytes and chicken embryo fibroblasts, were not killed by exposure to the Y4 sonic extract. No hemolytic activity was detected in the Y4 sonic extract. Consequently, the factor(s) in the Y4 sonic extract was referred to as Y4 leukotoxin. The Y4 leukotoxin was inactive at 40C, heat sensitive (560C, 30 min), and inactivated by proteases. The cytotoxic effect of Y4 leukotoxin on PMNs was dose, time, and temperature dependent. The leukotoxin did not bind to viable PMNs at 40C but

Bactericidal effect of pooled human serum on Bacteroides melaninogenicus, Bacteroides asaccharolyticus and Actinobacillus actinomycetemcomitans

“…This is in contrast to the results od'sAidal. (43), who have reported strain Y4 to be killed by pooled human serum. This difference can not yet be explained.…”

Bacterial invasion of the periodontium in a case of juvenile periodontitis

“…The bacteria seen in the soft tissue were very largely gram-negative (Figs. 6, 7) as are many of the current candidate pathogens of juvenile periodontitis, notably the Actinobacillus actinomycetemcomitans Y4 (Tsai et al 1979) and Capnocytophaga (Newman et al 1976) and this may account for the difficulty of detecting such organisms by light microscopy of gram-stained paraffin sections. It may be that electron microscopic examination is necessary to reveal such a diffuse gram-negative infiltrate.…”

“…9 shows a neutrophil in the connective tissue displaying this failure to degranulate following phagocytosis. Actinobacillus actinomycetemcomitans y.# is known to secrete a leucotoxin (Tsai et al 1979) active against PMN and monocytes and this may further reduce the efficiency of the PMN host defence.…”

Leukotoxin fromAggregatibacter actinomycetemcomitanscauses shrinkage and P2X receptor-dependent lysis of human erythrocytes

“…These repeats bind Ca 2+ and play a role in the interaction with the host cell surface Sanchez-Magraner et al, 2007;Linhartova et al, 2010). LtxA specifically kills leucocytes, particularly polymorphonuclear leucocytes and macrophages from humans, the Great Apes and Old World monkeys (Tsai et al, 1979;Taichman et al, 1984;1987). It is well established that the toxin uses b2-integrins on leucocytes as cell surface receptors (Lally et al, 1997;Kieba et al, 2007;Morova et al, 2008;J.…”