Acta microbiologica Academiae Scientiarum Hungaricae最新文献

Twenty five strains of Yersinia enterocolitica serogroup O3, were isolated from human enteritis and studied for heat-stable enterotoxin production. Enterotoxin production was found even in the crude supernatant fluid of cultures that had been stored in stock agar for a year. According to the suckling mice and rabbit gut loop tests, after 1 to 5 years storage the filtrate showed heat-stable enterotoxin activity only in a purified and concentrated form. Following more than 5 years storage positive results could be obtained only in rabbit gut loop test. After 9 years the freeze dried strains still showed a full capacity of heat-stable enterotoxin production. Studies with concentrated substances showed that even after more than 9 years, there was no spontaneous loss of heat-stable enterotoxin production, only quantitative changes occurred. The methanol solubility of the heat-stable enterotoxin of Y. enterocolitica is--as distinct from the heat-stable enterotoxin of Escherichia coli--homogeneous and only the methanol soluble fractions showed any activity. The activity of methanol soluble enterotoxin from several years old subcultures could be demonstrated in an isolated rabbit gut loop model even when it failed to show any activity in suckling mice.

Klebsiella pneumoniae strain B-5-1 was used to study the effect of its enterotoxin on the intestinal transport and histopathological changes in the rabbit ileal loop. Enterotoxin increased the net flux of water and of electrolytes. Increased amounts of phospholipids and proteins were also detected together with structural and functional abnormalities in the ileum. All these suggest that K. pneumoniae enterotoxin not only induce a net flux of fluid and imbalance of electrolytes but also damages the intestinal structure.

The effect of parent lipopolysaccharide (LPS) and radio-detoxified endotoxin (rdLPS) on various human blood cell membranes proved to be different as detected by 3H-concanavalin A-binding technique in vitro. The lectin-binding ability of erythrocyte membranes did not change upon treatment by either endotoxin, whereas that of lymphocytes was stimulated by LPS at 10-50 micrograms/ml concentration as well as by rdLPS at the lowest dose applied, i.e. 0.1 micrograms/ml. The LPS-treated platelets bound 3H-concanavalin A less than did the untreated controls; on the other hand, the rdLPS did not change the lectin-binding surface of these cells. The affection by radiation of cell membranes could be prevented by pretreatment with endotoxins. This fact, however, could not be considered a radioprotective effect. The micromorphological investigations by scanning electron microscopy (SEM) support our data concerning the functional alterations of plasma membranes of platelets and lymphocytes after LPS and rdLPS treatment as well as after the combined effect of endotoxin pretreatment and X-irradiation, since a severe smoothening of the cell surface could be observed.

Cytotoxic substance(s) of about 4 X 10(3) molecular weight, containing 9.5% peptide and 73% carbohydrate was released from Staphylococcus epidermidis in phosphate buffered saline. The material was soluble in ethanol and was heat-resistant. It blocked amino acid uptake and E-rosette formation of human tonsillar and blood lymphocytes. In isolated mouse hepatocytes the toxin inhibited protein synthesis, but only in the presence of calcium ions. The results suggest that eukaryotic cell membranes are damaged by the coccal agent.

Mice were actively immunized with preparations produced from different Salmonella strains. They were challenged with 2 LD50 of a virulent S. typhi-murium strain and examined for viable cell counts in the liver 4, 7 and 11 days postinfection. Whole cell vaccines, ribosomal extracts and endotoxin preparations of the O antigen-deficient variant of S. typhi-murium strain LT2-MI failed to protect the mice or did so in a much lower degree than preparations of the corresponding O antigen-bearing variant. Preparations from other salmonellae exerted a protective action only if the strain had an O-antigen identical with that of S. typhi-murium. The results pointed to a considerable protective role of the O antigen.

The same dose of dianhydrodulcitol (DAD) produced a lower mortality rate among germfree mice than among SPF or conventional C3H mice. On the other hand, it caused graver lymphoid atrophy in germfree mice. Their higher resistance, as evidenced by the mortality rate, can be explained on the basis of a histological study of the ileum. It showed milder alterations of the intestinal wall in germfree than in SPF mice. The lymphotropic cytostatic agent had a less direct toxic effect in germfree mice, due to the lacking damaging effect of endotoxin from the normal intestinal flora.

The aim of the study was to produce an efficacious formaldehyde inactivated, adsorbed vaccine from the Mongolian sheep-pox MH virus strain. Aluminium hydroxide gel prepared from AlCl3 X 6 H2O proved to be the most efficacious adsorbent among the gels prepared from different substances. Above 1.8% Al2O3 content the unadsorbed virus quantity was less than 1% of the original one. Using gel prepared from KAl(SO4)2 and AlCl3 X 6 H2O, respectively, the quantity of adsorbed virus was the same during the adsorption period from 10 min to 24 h. Intradermal inoculation of sheep proved more advantageous for virus production than subcutaneous inoculation. Three vaccines containing different quantities of antigen were prepared from virus propagated in sheep. The vaccine containing 19 800 ID50 inactivated virus did not protect the sheep even against a virus challenge of 25 ID50, while that of 67 000 ID50 content protected 50% of the animals infected with 125 to 287 ID50, and that of 395 000 ID50 content protected 100% of the animals against challenge with more than 100 000 ID50. More than 3 million sheep were inoculated in Mongolia with vaccines of 350 000 ID50 virus content in the last years. In the areas where vaccination has been introduced no sheep-pox epizootic has occurred.

Mycobacterium xenopi was isolated from the sputum of 21 patients with clinical signs of pulmonary disease and of 52 asymptomatic subjects living in the environment of a sludge pool. M. xenopi was cultured in high numbers from sludge samples. The infections were assumed to occur partly via dry sludge particles scattered by the wind in summer, and partly by sludge used as fertilizer.