[An antigenic analysis and the protective properties of the R-form lipopolysaccharides of gram-negative bacteria]. / Antigennyi analiz i protektivnye svoistva lipopolisakharidov R-form nekotorykh gramotritsatel'nykh bakterii.

The antigenic and immunogenic properties of the R-form lipopolysaccharides (R-LPS) of Pseudomonas aeruginosa, Salmonella minnesota, Escherichia coli and Shigella were studied. The results of the study revealed the existence of antigenic relationship between P.aeruginosa R-LPS and R-LPS Escherichia and Shigella. In serological tests no antigenic relationship between P. aeruginosa R-LPS and Salmonella R-LPS was revealed, but as shown in earlier experiments of the protection of mice, Re-glycolipid stimulated protective immunity against Pseudomonas infection in the animals. On the basis of R-LPS obtained from selected P. aeruginosa and Salmonella strains a vaccine was prepared which proved to be effective against infection caused by P. aeruginosa S-strain in experiments on mice. The vaccine induced protection in 40-100% of immunized mice, depending on the scheme of immunization. The vaccine may probably be effective against infections caused by other gram-negative bacteria.

R-form lipopolysaccharides (LPS) of Gram-negative bacteria as possible vaccine antigens.

The antigenic and immunogenic properties of R-form lipopolysaccharides (LPS) of Pseudomonas aeruginosa, Salmonella spp., Escherichia coli and Shigella spp. were studied. The results showed the presence of antigenic relationships among P. aeruginosa R mutants with different structures of the LPS core lipid A region and also among E. coli, Shigella and P. aeruginosa R-LPS, but not with S. minnesota Re-LPS. Vaccines prepared with R-LPS proved to be effective preparations for the active immunization of mice against P. aeruginosa infection. The vaccine stimulated 40-100% protection in mice depending upon the scheme of immunization.

[An immunological study of the cell wall proteins of Pseudomonas aeruginosa]. / Immunologicheskoe izuchenie belkov kletochnoi stenki Pseudomonas aeruginosa.

A preparation containing P. aeruginosa cell-wall proteins with a mol. wt. of 9-55 kD has been obtained from P. aeruginosa by the method of extraction with the use of tris-EDTA buffer. In experiments on mice this protein preparation has shown pronounced protective properties, but, according to the data of Shwartzman's local reaction, proved to be toxic, perhaps due to the admixture of LPS. The purification of the protein preparation from the admixture of LPS will make it possible to obtain an effective vaccine against P. aeruginosa infection.

Mouse protection induced by Pseudomonas aeruginosa PAC1R and its defective mutants, Salmonella minnesota Re-mutant and Escherichia coli O14.

Pseudomonas aeruginosa PAC1R and its defective mutants (acetone-killed bacteria), Salmonella minnesota Re mutant (acetone-killed bacteria and Re-LPS) and Escherichia coli O14 (acetone-killed bacteria and enterobacterial common antigen, ECA) were studied in a mouse active protection test. Immunized mice were challenged with wild-type P. aeruginosa strains. It was established that P. aeruginosa LPS-defective mutants induced cross-immunity against different Fisher immunotypes of P. aeruginosa. S. minnesota Re-LPS and ECA gave mice protection against P. aeruginosa.

Immunological studies of an artificial antigen with specificity of a common polysaccharide antigen of Pseudomonas aeruginosa.

Synthetic D-rhamnan, with the structure of Pseudomonas aeruginosa common polysaccharide antigen (CPA), was conjugated with BSA. The artificial antigen obtained, and the natural antigens, lipopolysaccharides (LPS) of P. aeruginosa and Pseudomonas cerasi with rhamnan chains of the same structure, were studied by ELISA with rabbit antibodies to the D-rhamnan-BSA conjugate and to the P. cerasi O-antigen. Immunological relations between the LPS of P. aeruginosa and P. cerasi determined by CPA as well as between these LPS and D-rhamnan-BSA were revealed by ELISA. O-antiserum to P. cerasi possesses protective activity in the mouse passive protection test when mice are challenged with some P. aeruginosa strains; the antiserum to the D-rhamnan-BSA does not possess protective activity in mice.

Specific and non-specific mouse protection induced by different chemotypes of the Pseudomonas aeruginosa lipopolysaccharides.

Lipopolysaccharides (LPS) of Pseudomonas aeruginosa were studied by the mouse active, cross-protection test. The primary structure of O-specific polysaccharides (O-repeating units) of different chemotypes was determined and their cross-protective activity demonstrated. Low doses of LPS (0.1-1 micrograms) stimulated chemotype-specific protection against P. aeruginosa in mice. This immunity was associated with the primary structure of the LPS and it lasted for 14 days after the first or second immunization. High doses of LPS (10-100 micrograms) induced cross-protection against P. aeruginosa in mice. The cross-protective capacity was caused evidently by the secondary structure or conformation of LPS molecule, i.e. by the common conformational protective determinant. This cross-protection lasted for only 5 days after the first or second immunization.

Antibodies against the common polysaccharide and protein protective antigens of Pseudomonas aeruginosa in normal blood donors.

Screening of normal plasma obtained from 172 blood donors from the Helsinki area and from 46 blood donors from the Moscow area was performed in order to reveal 'natural' antibodies to the common polysaccharide (rhamnan) and protein antigens of P. aeruginosa. Antibodies were detected by ELISA. Among blood donors from the Helsinki area high titres of antibodies to the protein antigens were detected in 42 active blood donors (24.4%) and very high titres in nine (5.3%) highly-active blood donors, whereas in the Moscow area in 15 (34.9%) and in one case (2.3%), respectively. Antibodies to the common polysaccharide antigen were determined in the Helsinki area in 23 active blood donors (13.4%) and in one (0.5%) highly active blood donor, whereas in the Moscow area in four active blood donors (8.6%). The plasma contained both polysaccharide and anti-protein antibodies. The level of antibodies to the polysaccharide antigen was lower than the level of antibodies to the protein antigens. There was no statistically significant difference between the corresponding values of blood donor groups from the Helsinki and Moscow areas.

[The immunological response in volunteer donors immunized with a Pseudomonas vaccine]. / Immunologicheskii otvet u donorov-dobrovol'tsev, immunizirovannykh vaktsinoi psevdomonas.

The trial of experimental vaccine consisting of protective protein antigens of P. aeruginosa cell wall was carried out on 114 volunteers. The vaccine proved to be faintly reactogenic and induced the formation of specific humoral immunity in 98% of the volunteers who retained a high level of anti-P. aeruginosa antibodies in their blood for up to 5 months (the term of observation after the course of immunization was over.

Clinico-immunological trials of Pseudomonas aeruginosa vaccine.

Pseudomonas aeruginosa vaccine (PV) containing predominantly cell-wall protein protective antigens was tested for safety and immunogenicity by immunization of 119 volunteers. The criteria for safety and immunogenicity were the absence of serious post-vaccinal reactions or complications either during immunization or 12 months later. There were mild (19 donors or 15.9%) and moderate (three donors or 2.5%) febrile reactions after immunization and in two volunteers the body temperature increased up to 38 degrees C, however it decreased to normal values within 24 h. We observed in 43 (36.1%) of volunteers mild and in five (4.2%) moderate local reactions which disappeared within 24 h. Using the ELISA and passive mouse protection test it was shown that PV induces the formation of specific antibodies. A high level of specific antibodies persisted for the 5-month period of observation. The antibody titres increased in 94-97% of volunteers and moreover in 45.6% the antibody titres (the number of ELISA units) increased 2.5-3-fold and more. Anti-P. aeruginosa plasma was used for the treatment of 46 patients with severe forms of P. aeruginosa infection (40 adults and six infants aged up to 2 years) and 87% of the patients recovered.

Detection of common polysaccharide antigen of Pseudomonas aeruginosa with O-antiserum to Pseudomonas cerasi.

The identity of the structures of common polysaccharide antigen (CPA) of Pseudomonas aeruginosa and O-antigen of Pseudomonas cerasi was used for immunochemical study of polysaccharide antigens of seven immunotypes (IT) of P. aeruginosa. ELISA performed with O-antiserum to P. cerasi showed that CPA is present in all seven ITs in different amounts. In SDS-PAGE this antigen behaves as a lipopolysaccharide (LPS) and is detected by immunoblotting technique in five of seven ITs.

[Immune response to a synthetic polysaccharide and protein conjugate]. / Immunnyi otvet k kon"iugatu sinteticheskogo polisakharida s belkom.

Synthetic polysaccharide (S-PS) containing aglycone-spacer with a free amino group was really alpha 1,6-mannan with Cn approximately 10. S-PS was transformed into isothiocyanate derivative by treating it with thiophosgene and engaged into reaction with amino group of bovine serum albumin (BSA) lysine residues. Rabbits were immunized with S-PS-BSA conjugate and antibodies to S-PS titres were estimated by means of ELISA. S-PS-BSA conjugate was proved to provoke specific anti-polysaccharide antibodies formation in rabbits.

Immunochemical and immunological study of cell-wall proteins of Pseudomonas aeruginosa.

Crude aqueous extract was obtained from acetone-dried cells of Pseudomonas aeruginosa strain 868 (serogroup O2, Lányi and Bergan's schema) and subjected to ultracentrifugation (105,000 g, 3 h); the lipopolysaccharide (LPS)-containing precipitate was discarded and the supernatant containing water-soluble cell proteins was subjected to further fractionation. From a partially purified aqueous extract two fractions were obtained by step-wise precipitation with ammonium sulphate, namely, F1 (by 50% saturation), and F2 (by 80% saturation). By gel and ion-exchange chromatography from both fractions 9 subfractions were isolated differing in molecular weight, protein content, and LPS contamination. Subfractions 4 and 7 were practically free from LPS, and gave one precipitation line with antisera for strain 868. By immunoelectrophoresis subfraction 4 contained 2 cathodic and 1 anodic, whereas subfraction 7 mainly 1 anodic component. These subfractions were antigenically identical. With ELISA these subfractions were less active as compared to other subfractions, in particular to those of high molecular weight. The anti-subfraction 4 and anti-subfraction 7 sera were found to protect passively mice against intraperitoneal challenge by P. aeruginosa strain 8 (serogroup O2). These data support the authors' opinion that subfraction SF-4 and SF-7 are protective protein antigens (mol wt about 40,000 and 30,000, respectively), that are localized in the outer membrane of P. aeruginosa cell envelope.

[Protective protein antigens of Pseudomonas aeruginosa]. / Belkovye protektivnye antigeny Pseudomonas aeruginosa.

Partially purified water extract was obtained from the initial water extract by ultracentrifugation. Nine protein fractions differing in molecular weight, homogeneity and the content of lipopolysaccharide (LPS) were obtained by stepwise precipitation with ammonium sulfate and subsequent fractionation in columns packed with Sephadex G-100 and DEAE cellulose. Two protein fractions with a molecular weight of 30000 and 40000 daltons were practically free of LPS. These fractions were homogeneous as shown by analytical centrifugation and formed a single precipitation line with P. aeruginosa antiserum; both fractions were found to be antigenically identical. In the enzyme immunoassay these two fractions proved to be least active in comparison with the other protein fractions, but when used for the immunization of rabbits, they induced the formation of specific protective (for mice) antibodies. Both antisera were equally active in the experiments of the passive protection of mice. The isolated LPS-free proteins are supposed to be the proteins of the outer membrane of P. aeruginosa cell wall and have the properties of protective antigens.