Search PubMed⌕ Search

Biomedical subjects

J C Sadoff

Publications and source records attributed to J C Sadoff.

At least 73 records · Page 4Linked to original sources
PubMed1990

Synthesis and characterization of Escherichia coli O18 O-polysaccharide conjugate vaccines.

Nontoxic, serologically reactive O polysaccharide was derived from Escherichia coli O18 lipopolysaccharide by acid hydrolysis, extraction with organic solvents, and gel filtration chromatography. Oxidized O polysaccharide was covalently coupled to either Pseudomonas aeruginosa toxin A or cholera toxin by using adipic acid dihydrazide as a spacer molecule in the presence of carbodiimide. The resulting conjugates were composed of approximately equal amounts of O polysaccharide and protein and were nontoxic and nonpyrogenic. Both conjugates engendered an immunoglobulin G antibody response in rabbits that recognized native O18 lipopolysaccharide. Such antibody was able to promote the uptake and killing of an E. coli O18 strain bearing the K1 capsule by human polymorphonuclear leukocytes. Immunoglobulin G isolated from the sera of rabbits immunized with either conjugate afforded protection against an E. coli O18 challenge when passively transferred to mice.

ADP Ribose Transferases↗
PubMed1990

Escherichia coli and Klebsiella vaccines and immunotherapy.

A polyvalent vaccine has been prepared from the capsular polysaccharide of 24 different serotypes of Klebsiella spp. Nearly 200 volunteers have received this vaccine. It is very well tolerated and elicits both binding (ELISA) and functional antibody to 21 of 24 antigens. Antibodies were also detected against 10 serotypes not included in the vaccine. An immunoglobulin for intravenous use (IVIG) was more protective in mouse lethality assays and enhanced opsonophagocytic killing of bacteria more than standard, nonhyperimmune globulin. A monovalent E. coli conjugate vaccine against O18ac antigen was safe and highly immunogenic in humans. A 12-valent conjugate vaccine elicits good levels of antibody in rabbits, and will soon undergo phase I testing in humans. These vaccines might best be used for inducing antibody in donor plasma that could be made into IVIG for passive administration.

Bacterial Vaccines↗
PubMed1989

Pretreatment with recombinant murine tumor necrosis factor alpha/cachectin and murine interleukin 1 alpha protects mice from lethal bacterial infection.

Tumor necrosis factor/cachectin (TNF/C) is the principal mediator of bacterial endotoxin-induced shock and death. We found that the C3H/HeJ mouse, which is less able to produce TNF/C in response to endotoxin, has a 1,000-fold greater susceptibility to lethal infection with Escherichia coli than the TNF-responsive congenic mouse, C3H/HeN. This surprising finding suggested that this lethal peptide may also be involved in host protection. To test this hypothesis we pretreated the C3H/HeJ mouse with a combination of recombinant murine TNF/C-alpha and IL-1 alpha. This combination protected these mice against an intraperitoneal bacterial challenge of greater than 20 LD50S (nearly 2 x 10(2) CFU) that grew to a level of greater than 10(7) CFU/ml of blood and per gram of liver in untreated mice. This suggests a significant role for these cytokines in host defenses against invasive infections that require bacterial replication within the host. These protective mechanisms may not be important for less virulent organisms. These findings may have important implications for the proposed use of anti-TNF/C agents in the treatment of septic shock.

Animals↗
PubMed1989

Cloning and sequencing of the Pseudomonas aeruginosa 1244 pilin structural gene.

The pilin structural gene of Pseudomonas aeruginosa 1244 was cloned in both cosmids and lambda. Expression of the cloned gene was detected in P. aeruginosa strains PAO2003, PA103, and 653A by an immunoblot reaction utilizing monoclonal antibodies. Western blot analysis showed that pilin expressed from the cloned gene was slightly larger than native 1244 pilin when produced in strains PAO2003 and 653A, but distinctly smaller in PA103. Bacteriophages specific for the 1244 pilus did not lyse strain PAO2003 containing the cloned 1244 pilin gene, indicating that functional 1244 pili were not assembled in this recombinant strain. Nucleotide sequencing revealed a coding region which when translated would produce a 15,615 dalton peptide. The amino-terminal region of this peptide is identical with published pilin sequences. While the rest of the peptides are generally dissimilar, common residues are seen within potentially antigenic regions.

Amino Acid Sequence↗
PubMed1989

Octavalent Pseudomonas aeruginosa O-polysaccharide-toxin A conjugate vaccine.

An octavalent Pseudomonas aeruginosa conjugate vaccine was synthesized by covalently coupling the O-polysaccharide (O-PS) moiety derived from lipopolysaccharides of Habs serotypes 1, 2, 3, 4, 5, 6, 11 and 12 to toxin A. Adipic acid dihydrazide was used as a spacer molecule to facilitate conjugation. The vaccine was composed of 37% (w/w) O-PS and 63% toxin A, devoid of enzymatic activity characteristic of toxin A, non-toxic for mice and guinea pigs, and non-pyrogenic. The vaccine elicited a significant rise in immunoglobulin G antibody levels to all serotypes of lipopolysaccharide contained in the vaccine and to toxin A. Serotypes 6, 10 and 11 were most immunogenic in mice whereas serotypes 1 and 5 engendered the lowest antibody response. Antitoxin A antibody was able to neutralize the cytotoxicity of toxin A. Immunization of mice with the vaccine conferred significant protection against subsequent challenge with all P. aeruginosa serotype strains contained in the vaccine.

Animals↗
PubMed1989

Oral ciprofloxacin and a monoclonal antibody to lipopolysaccharide protect leukopenic rats from lethal infection with Pseudomonas aeruginosa.

To study the treatment of infection with Pseudomonas aeruginosa, a leukopenic rat model was developed that closely mimics the pathogenesis of Pseudomonas infection in man. This model achieved approximately 90% mortality within 10 d of infection. Pseudomonas organisms were inconsistently shed from the feces despite gastrointestinal colonization (9 fecal v. 23 cecal cultures positive for challenge strain in 28 rats). Treatment of rats with oral ciprofloxacin at 40 mg/kg afforded complete protection. A suboptimal dose of ciprofloxacin (20 mg/kg), achieving peak levels of 0.31 micrograms/mL in serum and 26.3 micrograms/mL in stool, resulted in survival of 8 (40%) of 20 rats. Intraperitoneal administration of a monoclonal antibody directed at the lipopolysaccharide of the challenge strain of Pseudomonas resulted in survival of 5 rats (26%). The combination of the two increased the survival to 75% (15 of 20, P less than 0.05 compared to either treatment alone). Thus, the combination of suboptimal doses of ciprofloxacin and a monoclonal antibody appears to protect leukopenic rats from lethal infection better than either treatment alone.

Administration, Oral↗
PubMed1989

The human antibody response during natural bacteremic infection with gram-negative bacilli against lipopolysaccharide core determinants.

The class-specific antibody response was measured in sequential serum samples from 17 patients after natural bacteremic infection with gram-negative bacilli. There was a five- to sevenfold mean increase over preexisting antibody in levels of IgG (range, less than 1-to 88-fold), IgA (1- to 83-fold), and IgM (less than 1- to 58-fold) antibody to homologous lipopolysaccharide (LPS) in 16 of these patients. In contrast, there was only a two- to threefold mean increase (range, less than 1- to 78-fold) in about half of the patients who had a detectable antibody response to J5 core determinants and in the third who responded to Re core determinants (range, 1- to 20-fold). All but one of the infective strains of bacteria were smooth on analysis with SDS-PAGE and with rough-specific phages. Humans infected with bacteria that had a rough LPS phenotype, however, did elicit antibody similar to that induced in rabbits after immunization with J5 vaccine. Thus, the human antibody response to natural infection with gram-negative bacilli appears to be directed primarily at homologous, strain-specific epitopes, and the response to the epitopes of LPS core antigens is not against widely shared determinants.

Adolescent↗
PubMed1988

Oral Salmonella typhimurium vaccine expressing circumsporozoite protein protects against malaria.

Immunization with radiation-attenuated malaria sporozoites induces potent cellular immune responses, but the target antigens are unknown and have not previously been elicited by subunit vaccines prepared from the circumsporozoite (CS) protein. A method is described here for inducing protective cell-mediated immunity to sporozoites by immunization with attenuated Salmonella typhimurium transformed with the Plasmodium berghei CS gene. These transformants constitutively express CS antigens and, when used to immunize mice orally, colonize the liver, induce antigen-specific cell-mediated immunity, and protect mice against sporozoite challenge in the absence of antisporozoite antibodies. These data indicate that the CS protein contains T cell epitopes capable of inducing protective cell-mediated immunity, and emphasize the importance of proper antigen presentation in generating this response. Analogous, orally administered vaccines against human malaria might be feasible.

Animals↗
PubMed1988

A murine monoclonal antibody against Klebsiella capsular polysaccharide is opsonic in vitro and protects against experimental Klebsiella pneumoniae infection.

Murine monoclonal antibodies (mAb) of the immunoglobulin M class specific for the K2 capsular polysaccharide (CPS) of Klebsiella were isolated. One such mAb, termed III/5-1, was selected for further study. This mAb promoted the uptake and killing of Klebsiella pneumoniae K2 strains by human granulocytes and activated complement after contact with the bacteria. The efficiency of mAb-mediated phagocytosis and complement activation was inversely related to the amount of capsular material produced by the test strain. MAb III/5-1 was found to be effective at preventing fatal experimental K. pneumoniae K2 sepsis when administered prophylactically, the degree of protection being dependent upon the amount of CPS produced by the challenge strain.

Animals↗
PubMed1988

Effect of carrier selection on immunogenicity of protein conjugate vaccines against Plasmodium falciparum circumsporozoites.

Conjugate vaccines against the sporozoite stage of Plasmodium falciparum were synthesized by covalently coupling the recombinant protein R32 [with the one-letter amino acid code of MDP-[(NANP)15NVDP]2LR] to tetanus toxoid, cholera toxin, choleragenoid, and Pseudomonas aeruginosa toxin A. Conjugates were produced by using adipic acid dihydrazide as a spacer molecule and carbodiimide as a coupling agent. The molar ratio of R32 to carrier protein ranged from 2.5:1 to 8.4:1. These conjugates were found to be stable, nontoxic, and nonpyrogenic. When adsorbed onto Al(OH)3, all conjugates were capable of inducing anti-R32 antibody. Conjugates made with either cholera toxin or Pseudomonas aeruginosa toxin A were significantly more immunogenic than those constructed with tetanus toxoid or choleragenoid. However, the magnitude of the immune response to the R32 moiety was not governed by the antibody response to the carrier protein.

Amino Acid Sequence↗
PubMed1988

Immunization with a Pseudomonas aeruginosa immunotype 5 O polysaccharide-toxin A conjugate vaccine: effect of a booster dose on antibody levels in humans.

Healthy adult volunteers were vaccinated on day 0 and 28 and at 15 months with a Pseudomonas aeruginosa immunotype 5 O polysaccharide-toxin A conjugate vaccine. Immunization resulted in mild, transient local reactions in less than 20% of the subjects. Maximal immunoglobulin G (IgG) antibody titers to both toxin A and lipopolysaccharide (LPS) as determined by enzyme-linked immunosorbent assay were seen at day 42, at which time 50% of the vaccinees showed a fourfold or greater rise in toxin A-neutralizing titers. By 15 months postvaccination, both antitoxin A and anti-LPS IgG antibodies had markedly declined. A booster dose of vaccine administered at 15 months evoked a vigorous anti-toxin A IgG antibody response with 100% of the volunteers showing a fourfold or greater rise in neutralizing antibody titer compared with preimmunization levels. In contrast, there was no significant elevation of anti-LPS IgG antibody levels. At 24 months postimmunization, only anti-toxin A antibody levels were significantly higher than preimmunization levels.

Adult↗
PubMed1988

Induced engulfment of Neisseria gonorrhoeae by tissue culture cells.

Engulfment of gonococci by mammalian tissue culture cells was examined as a model of the penetration of host cells in gonorrhea. Engulfment required viable organisms; killing the gonococci with heat or refrigeration abolished the process. Engulfment also required tissue culture cell microtubule- and microfilament-dependent movement; treating the cells with cytochalasin B (0.5 micrograms/ml) or demecolcine (Colcemid; Ciba-Geigy AG, Basel, Switzerland) (10 micrograms/ml) also prevented his process.

Animals↗
PubMed1988

Characterization of the human immune response to a Pseudomonas aeruginosa O-polysaccharide-toxin A conjugate vaccine.

We characterized the immune response in humans after vaccination with a Pseudomonas aeruginosa immunotype 5 O-polysaccharide (O-PS)-toxin A conjugate vaccine. The majority of volunteers responded with an immunoglobulin G (IgG) antibody response on enzyme-linked immunosorbent assay (ELISA) to both the toxin A and the lipopolysaccharide (LPS) components of the vaccine. Maximal titers to both vaccine components were seen 42 days after immunization. Antibody levels remained elevated for at least 14 months after vaccination. The anti-LPS IgG response was predominantly within the IgG1 and IgG2 subclasses, whereas the antitoxin A response was within the IgG1 subclass. There was a gradual elevation of IgG4 antitoxin antibody, with maximal levels seen at 14 months after immunization. No concomitant IgG4 antibody rise to LPS was observed. Immunization evoked a vigorous IgA1 and IgA2 antibody response to LPS, which was long-lived. Only a modest, transient IgA antitoxin A response was noted. Both antitoxin A--neutralizing and opsonic antibodies were elicited by immunization and remained elevated over the 14-month postimmunization period studied.

Antibodies, Anti-Idiotypic↗
PubMed1987

Immunotoxins to a human melanoma-associated antigen: comparison of gelonin with ricin and other A chain conjugates.

Gelonin, a ribosome-inactivating protein from the seeds of Gelonium multiflorum, has been conjugated to antibodies. Previous reports have indicated variable potency of such immunotoxins. The lack of toxicity of gelonin, however, makes it attractive for immunoconjugate production. The ribosome-inactivating protein was covalently linked (using N-succinimidyl-3-(2-pyridyldithio)propionate) to monoclonal antibody, 9.2.27, directed to a human melanoma-associated glycoprotein/proteoglycan. The immunoconjugate showed high selectivity with dose-dependent cytotoxic activity to cultured human melanoma cells (50% inhibitory dose; 1-3 X 10(-11) M versus antigen-positive cells; 1-3 X 10(-7) M versus antigen-negative cells). Specificity and immunoreactivity of the conjugate were similar to those of unconjugated antibody. Biodistribution studies with iodine trace-labeled conjugate in nude mice indicated that tumor localization of the gelonin conjugate was decreased compared to unconjugated antibody. However, a significant therapeutic effect of the conjugate was found with multiple but not single dose i.v. treatment in nude mice bearing established palpable melanoma. These in vivo experiments showed that gelonin conjugates are not toxic up to 2 mg total dose/mouse and significantly retarded the growth of established s.c. tumor. Comparison of gelonin conjugates in vitro and in vivo with other A-chain conjugates of 9.2.27 (abrin and ricin) indicated that gelonin had similar potency, better selectivity, better tumor localization, and more significant therapeutic effects.

Abrin↗
PubMed1987

Localization of plasmid loci necessary for the entry of Shigella flexneri into HeLa cells, and characterization of one locus encoding four immunogenic polypeptides.

We have previously cloned a 44 kb fragment from the virulence plasmid of Shigella flexneri serotype 5 strain M90T which is capable of restoring invasiveness to an avirulent, plasmidless mutant. This report presents a genetic and physical analysis of Tn5 mutations in recombinant clone pHS4108. Tn5 mutagenesis allowed identification of at least five regions implicated in the entry phenotype. These regions were located on a 20 kb portion of pHS4108. Expression of the insertion mutants was studied by immunoblots using the serum of a convalescent monkey infected by S. flexneri 2a, which recognized four plasmid-associated polypeptides. We propose that the four immunogenic polypeptides, a, b, c, and d, are encoded an operon.

Chromosome Mapping↗