Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “DIPHTHERIA”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 847 records · Page 47Linked to original sources
PubMed2000

Diphtheria surveillance and control in the Former Soviet Union and the Newly Independent States.

The Newly Independent States (NIS) inherited a common approach to diphtheria control from the Soviet Union and maintained a centralized system of surveillance and control managed by Soviet-trained epidemiologists with a shared professional culture. This system had controlled a diphtheria resurgence in the 1980s. In response to the epidemic of the 1990s, NIS health authorities responded with a set of control measures based on the Soviet-era experience. These measures included intensified childhood vaccination, aggressive case investigation, widespread diphtheria screening in institutions, and vaccination of adults in high-risk occupation groups. These measures proved insufficient due to high levels of susceptibility among adults, excessive contraindications to childhood vaccination, and insufficient resources in many countries. After these initial delays in implementing effective measures in some countries, most of the NIS health authorities rapidly and successfully implemented mass immunization of the population against diphtheria once the strategy was adopted and sufficient vaccine was available.

Adult↗
PubMed2002

Cell-specific Cre-mediated activation of the diphtheria toxin gene in pituitary tumor cells: potential for cytotoxic gene therapy.

Diphtheria toxin has been suggested for the treatment of malignant cancer. In this paper, we describe a strategy for targeting the expression of the diphtheria toxin gene to growth hormone (GH)-producing pituitary tumor cells using adenoviral vectors. We generated adenoviral vectors in which a stuffer DNA fragment, flanked by two loxP sequences, was placed between the GH or cytomegalovirus (CMV) promoters and the diphtheria toxin gene (GH-loxP-DT, and CMV-loxP-DT) or the beta-Gal gene (GH-loxP-Gal, and CMV-loxP-Gal). Co-infection of GH-loxP-DT with either CMV-Cre or GH-Cre induced cytotoxicity that was limited to GH4 cells. Little or no cytopathic effect was seen in GH4 cells infected with control viruses (CMV-loxP-Gal or GH-loxP-Gal with CMV-Cre or GH-Cre). To test the effectiveness of this strategy in vivo, GH4 cells were transplanted into nude mice. Intratumoral co-injection of adenoviruses carrying diphtheria toxin (GH-loxP-DT, and CMV-loxP-DT) and Cre recombinase (GH-Cre, and CMV-Cre) caused rapid regression of the transplanted GH4 tumors. These results indicate that Cre-mediated activation of a loxP-repressed form of the DT gene provides a useful strategy for targeted suicide gene therapy. This approach may be useful for GH-secreting adenomas and should be applicable to other neoplastic disorders.

Adenoviridae↗
PubMed1984

Corynebacterium diphtheriae endocarditis: sustained potential of a classical pathogen.

This communication concerns a case of endocarditis caused by Corynebacterium diphtheriae. The patient was a 35-year-old male drug addict who was brought to the hospital with fever, chills, and abdominal pain. Two days after admission, blood cultures were found to be growing gram-positive rods suggestive of diphtheroids. Repeated blood cultures grew the same organism, which was identified as a nontoxigenic strain of C. diphtheriae. The patient subsequently was identified as having acquired immune deficiency syndrome. Although isolates are divided into toxigenic and nontoxigenic strains, all isolates of C. diphtheriae should be considered potentially toxigenic. Because diphtheria generally is considered only of historic interest, few laboratories perform tests to identify it and instead report all isolates as "diphtheroids" or Corynebacterium. Because all isolates are potentially toxigenic, and because there is a large reservoir of nonimmunized people, laboratories must be alert to possible serious epidemiologic situations.

Acquired Immunodeficiency Syndrome↗
PubMed1998

Immunity to tetanus, diphtheria and poliomyelitis in the adult population of Sweden in 1991.

BACKGROUND: During 1990 and 1991 a survey of immunity was carried out in Sweden. The main purpose was to estimate the level of immunity to diphtheria, tetanus and polio in the adult population. In total, 4800 people, randomly selected according to a stratified, two-stage, sampling plan, were contacted and asked to contribute a blood sample. Of those selected, 70.6% gave a blood sample. METHODS: Estimates and confidence intervals of the proportion of the population with antibodies exceeding some titre was calculated. The population was divided according to sex, year of birth (five age groups) and residence (four regions). RESULTS: In age groups that were born after the introduction of childhood vaccination, > or =90% and 75-90% of people have demonstrable antibodies at a protective level against tetanus and diphtheria respectively. Those born earlier, especially women, are poorly protected with less than 50% having protective antibody levels for both tetanus and diphtheria. Differences between men and women were particularly seen in the age groups born between 1930 and 1950. Less than 5% of the Swedish population lacked the protective level antibodies against polio types 1, 2 and 3 respectively. CONCLUSIONS: Vaccination against tetanus, which can be combined with vaccination against diphtheria, can be recommended especially to women born before 1950 and with no documented previous vaccination. The same recommendation can be given for men born before the 1930s. As regards poliomyelitis, general booster vaccination of the adult population does not appear to be necessary at present.

Adult↗
PubMed2001

In vitro activity of ketolides HMR 3004 and HMR 3647 and seven other antimicrobial agents against Corynebacterium diphtheriae.

The in vitro activities of two ketolides, HMR 3004 and HMR 3647 (telithromycin), and the comparator agents erythromycin A, azithromycin, clarithromycin, roxithromycin, levofloxacin, ofloxacin and penicillin G were determined by an agar dilution method against 410 isolates of Corynebacterium diphtheriae. Test isolates originated from diverse geographical locations, including the former USSR, where epidemic diphtheria has re-emerged during the 1990s. All isolates tested were susceptible to penicillin G, ofloxacin and levofloxacin. The two ketolides and four macrolides were highly active against 405 of the 410 isolates. HMR 3004 was the most active of the drugs, followed by HMR 3647, clarithromycin, erythromycin A, roxithromycin and azithromycin. Five isolates showed reduced susceptibility to all macrolides and ketolides tested; three were non-toxigenic isolates from Australia and the remaining two were from cases of diphtheria in Vietnam. Inducible (MLS(B)) resistance was detected in the isolates from Vietnam, but not in the isolates originating from Australia. Significant antimicrobial resistance remains rare amongst C. diphtheriae; nevertheless, new ketolide antimicrobials may have a role to play in the treatment and control of this re-emergent pathogen.

Anti-Bacterial Agents↗
PubMed1975

Antitumor effects of antibody-diphtheria toxin conjugates. III. Cyclophosphamide-induced immune unresponsiveness to conjugates.

Of 9 hamsters immunized with diphtheria toxin-hamster gamma-globulin conjugates and rechallenged with this antigen 15 days later, 8 exhibited neutralizing antibodies against the conjugates 22 days after the initial immunization. Hamsters identically immunized, but also given cyclophosphamide (CY) 20 hours after the first immunization, had a much lower incidence of positive responses (2/10) and lower antibody levels in the positive responders. After further immunization with the conjugates, all CY-treated hamsters eventually developed neutralizing antibodies, but exhibited a reduction in antibody levels after a second exposure to CY. Hamsters immunized with diphtheria toxoid developed antibodies that were effective in neutralizing diphtheria toxin, but less effective against the diphtheria toxin conjugates.

Animals↗
PubMed1988

Gene for the diphtheria toxin-susceptible elongation factor 2 from Methanococcus vannielii.

Protein synthesis elongation factor 2 (EF-2) from all archaebacteria so far analysed, is susceptible to inactivation by diphtheria toxin, a property which it shares with EF-2 from the eukaryotic 8OS translation system. To resolve the structural basis of diphtheria toxin susceptibility, the structural gene for the EF-2 from an archaebacterium, Methanococcus vannielii, was cloned and its nucleotide sequence determined. It was found that (i) this gene is closely linked to that coding for elongation factor 1 alpha-(EF-1 alpha), (ii) the size of the gene product, as derived from the nucleotide sequence, lies between those for EF-2 from eukaryotes and eubacteria, (iii) it displays a higher sequence similarity to eukaryotic EF-2 than to eubacterial homologues, and (iv) the histidine residue which is modified to diphthamide and then ADP-ribosylated by diphtheria toxin is present in a sequence context similar to that of eukaryotic EF-2 but it is not conserved in eubacterial EF-G. The EF-2 gene from Methanococcus is expressed in transformed Saccharomyces cerevisiae but is not ADP-ribosylated by diphtheria toxin. This indicates that the Saccharomyces enzyme system is unable to post-translationally convert the respective histidine residue from the Methanococcus EF-2 into diphthamide.

Adenosine Diphosphate Ribose↗
PubMed1995

Production, characterization and cytotoxic properties of a diphtheria toxin-ciliary neurotrophic factor fusion protein.

Ciliary neurotrophic factor (CNTF) is a multifunctional cytokine that can regulate the survival and differentiation of many types of developing and adult neurons. This study describes the genetic construction, expression, purification and properties of a diphtheria toxin-related CNTF fusion gene in which the native receptor binding domain of diphtheria toxin was genetically replaced with a synthetic gene encoding human CNTF. The fusion protein expressed from the chimeric tox gene was designated DAB389-CNTF. This fusion toxin has a deduced molecular weight of 67 440 and is formed by the fusion of the first 389 amino acids of diphtheria toxin to amino acids 15-200 of mature human CNTF (Cys17-->Ser), using a bridge of 34 additional amino acids including six consecutive histidine residues. This latter span allows for a single-step purification of the fusion protein by Ni(2+)-immobilized metal ion affinity chromatography, and provides a degree of flexibility which facilitates polypeptide refolding. DAB389-CNTF was selectively cytotoxic for clonal cells bearing CNTF receptors and for CNTF-responsive spinal sensory ganglion neurons in primary culture. The cytotoxic action of DAB389-CNTF, like that of native diphtheria toxin, required receptor-mediated endocytosis, passage through an acidic compartment and delivery of an ADP-ribosyltransferase to the cytosol of target cells. The delivery of the catalytic domain to the target cell cytosol results in inhibition of protein synthesis and cell death. This latter point was confirmed by the observation that both CNTF and DAB389-CNTF increased c-fos mRNA expression, but only CNTF induced Fos protein.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1997

Safety and immunogenicity of a combined pentavalent diphtheria, tetanus, acellular pertussis, inactivated poliovirus and Haemophilus influenzae type b-tetanus conjugate vaccine in infants, compared with a whole cell pertussis pentavalent vaccine.

BACKGROUND: We compared the safety and immunogenicity of two combined diphtheria-tetanus-pertussis-inactivated poliovirus vaccines containing either acellular (Pa, SmithKline Beecham Biologicals) or whole cell (Pw, Pasteur Merieux Connaught) pertussis components, mixed with a Haemophilus influenzae type b polysaccharide polyribosylribitol phosphate-tetanus conjugate vaccine in an open, randomized study in healthy infants. DESIGN: The combined vaccines were given at 2, 4, 6 and 12 months of age, and serum samples were obtained at ages 2, 6, 7, 12 and 13 months. Adverse events were obtained by diary cards. RESULTS: The Pa group (n = 101) had a clearly lower incidence of both local and systemic adverse events than the Pw group (n = 100). Immunogenicity was comparable for the diphtheria and tetanus components, but significantly superior for pertussis toxin, filamentous hemagglutinin, pertactin and polioviruses 1, 2 and 3 in the Pa group. Both groups had an appropriate response with regard to H. influenzae type b polysaccharide polyribosylribitol phosphate, but the dynamics of the response were significantly different: geometric mean concentrations (micrograms per ml) after the second, third and booster doses were 1.27, 5.06 and 23.12 in the Pa group and 2.72, 6.66 and 13.59 in the Pw group, respectively (P = 0.0002 after second dose; P = 0.0005 after booster). CONCLUSION: The presently studied diphtheria, tetanus, acellular pertussis-H. influenzae b vaccine conjugated to tetanus toxoid combination was at least as immunogenic as the diphtheria, tetanus, whole cell pertussis-H. influenzae b vaccine conjugated to tetanus toxoid combination, with a significantly better safety profile. This is of obvious importance in countries where inactivated poliovirus vaccine is part of the routine infant immunization programs.

Antibodies, Bacterial↗
PubMed2002

Antibody response to an eleven valent diphtheria- and tetanus-conjugated pneumococcal conjugate vaccine in Filipino infants.

BACKGROUND: Pneumococcal conjugate vaccines are intended to provide effective protection against pneumococcal infections, but very little information on antibody responses in infants living in countries with high pneumococcal disease burden exists. METHODS: In this study 50 healthy Filipino infants were enrolled at a village health center in Cabuyao to receive 11-valent diphtheria- and tetanus-conjugated pneumococcal vaccine at 6, 10 and 14 weeks of age (primary series) simultaneously with diphtheria-tetanus-whole cell pertussis/polyribosylribitol phosphate conjugated to tetanus toxoid, hepatitis B virus and oral poliovirus vaccines and at 9 months of age (booster dose) simultaneously with measles vaccine. The alum-adjuvanted study vaccine contained pneumococcal polysaccharide of serotypes 1, 4, 5, 7F, 9V, 19F and 23F conjugated to tetanus protein and pneumococcal polysaccharide of serotypes 3, 6B, 14 and 18C conjugated to diphtheria toxoid. Serum samples for enzyme immunoassay analyses were collected at 6, 10 and 14 weeks and 9 and 10 months of age. RESULTS: Very high geometric mean antibody concentrations (GMCs) against most pneumococcal serotypes were observed after the first three doses of vaccine (range, serotype 23F, 3.89 microg/ml to serotype 4, 23.41 microg/ml) with the exception of serotype 6B and 14, with GMCs of 1.12 and 2.18 microg/ml, respectively. The fourth dose increased the GMCs against most serotypes (range, serotype 14, 1.65 to serotype 19F, 33.43 microg/ml). The maternally derived antibodies did not decrease the response to the vaccine. CONCLUSIONS: This first pneumococcal conjugate vaccine study in Asia confirms that the 11-valent diphtheria- and tetanus-conjugated pneumococcal vaccine is highly immunogenic in Filipino infants. The GMCs against most pneumococcal serotypes were substantially higher than described with the same or other pneumococcal conjugate vaccines in other populations.

Antibody Formation↗
PubMed2006

Combined diphtheria-tetanus-pertussis vaccine for tetanus-prone wound management in adults.

INTRODUCTION: Booster vaccination against tetanus, diphtheria and pertussis is recommended throughout life. Adults are difficult to reach and vaccination coverage in this group is often inadequate. The use of a reduced-antigen content combined diphtheria-tetanus-acellular pertussis ('adult' dTpa) vaccine for tetanus prophylaxis in emergency room wound management provides an opportunity to boost immunity against three infections simultaneously, thereby optimizing the efficiency of medical interventions with adults assessed. METHODS: A single-blind, randomized, controlled study of 320 healthy adults, the anti-tetanus antibody response within 10 days following vaccination with Boostrix (reduced-antigen diphtheria-tetanus-acellular pertussis). RESULTS: The anti-tetanus antibody response to the reduced-antigen diptheria-tetanus-acellular pertussis vaccine was equivalent to Tetavax, a licensed monovalent tetanus-toxoid vaccine. CONCLUSION: The use of diphtheria-tetanus-acellular pertussis is a safe and effective way to provide vaccination to adults against three diseases during emergency room visits for wound management.

Adult↗
PubMed2004

Sortases and pilin elements involved in pilus assembly of Corynebacterium diphtheriae.

Corynebacterium diphtheriae SpaA pili are composed of three pilin subunits, SpaA, SpaB and SpaC. SpaA, the major pilin protein, is distributed uniformly along the pilus shaft, whereas SpaB is observed at regular intervals, and SpaC seems to be positioned at the pilus tip. Pilus assembly in C. diphtheriae requires the pilin motif and the C-terminal sorting signal of SpaA, and is proposed to occur by a mechanism of ordered cross-linking, whereby pilin-specific sortase enzymes cleave precursor proteins at sorting signals and involve the side-chain amino groups of pilin motif sequences to generate covalent linkages between pilin subunits. We show here that two elements of SpaA pilin precursor, the pilin motif and the sorting signal, are together sufficient to promote the polymerization of an otherwise secreted protein by a process requiring the function of the sortase A gene (srtA). Five other sortase genes are dispensable for SpaA pilus assembly. Further, the incorporation of SpaB into SpaA pili requires a glutamic acid residue within the E box motif of SpaA, a feature that is found to be conserved in other Gram-positive pathogens that encode sortase and pilin subunit genes with sorting signals and pilin motifs. When the main fimbrial subunit of Actinomyces naeslundii type I fimbriae, FimA, is expressed in corynebacteria, C. diphtheriae strain NCTC13129 polymerized FimA to form short fibres. Although C. diphtheriae does not depend on other actinomycetal genes for FimA polymerization, this process involves the pilin motif and the sorting signal of FimA as well as corynebacterial sortase D (SrtD). Thus, pilus assembly in Gram-positive bacteria seems to occur by a universal mechanism of ordered cross-linking of precursor proteins, the multiple conserved features of which are recognized by designated sortase enzymes.

Amino Acid Sequence↗
PubMed1980

Increased toxicity of diphtheria toxin for human lymphoblastoid cells following covalent linkage to anti-(human lymphocyte) globulin or its F(ab')2 fragment.

Anti-(human lymphocyte) globulin was reacted with a mixed anhydride derivative of chlorambucil to give a product which was in turn reacted with diphtheria toxin. The resulting conjugate was partially purified and was found to possess an ability similar to that of the native antibody to bind to the human lymphoblastoid cell lines, CLA4 and Daudi. Daudi cells, as had been observed previously with CLA4 cells, lacked the high sensitivity to diphtheria toxin normally characteristic of cells of human origin. Thus treatment with free toxin at a concentration of 1 microgram/ml was without effect upon their ability to incorporate [3H]leucine. By contrast, Daudi cells were highly sensitive to toxin conjugated to anti-(human lymphocyte) globulin or to its F(ab')2 fragment. Exposure for 24 h to a solution of conjugate containing toxin at a concentration of 0.5 ng/ml caused a reduction of 50% in the leucine uptake by Daudi cells. The toxicity of the conjugate could be blocked by diphtheria antitoxin or by pretreatment of the cells with non-conjugated antibody. Toxin linked to normal horse IgG or to its F(ab')2 fragment was without cytotoxic effect upon Daudi cells. Furthermore both the conjugate with anti-(human lymphocyte) globulin and that with normal IgG were approximately 100-fold less able than non-conjugated toxin to inhibit protein synthesis by a human fibroblast cell line to which the antibody showed no appreciable binding. Thus the conjugates are relatively ineffective against cells which lack an antigen to which the antibody moiety can bind. In contrast with the greatly increased toxicity of diphtheria toxin for human lymphoblastoid cells following its linkage to anti-(human lymphocyte) globulin, a conjugate of toxin linked to anti-(mouse lymphocyte) globulin was ineffective against murine spleen cells in vitro.

Animals↗
PubMed1982

Inhibition of mitochondrial protein synthesis and energy coupling by fragment A of diphtheria toxin.

The effect of intact diphtheria toxin and its fragment A on energy-dependent functions in mouse liver mitochondria/mitoplasts has been studied. Fragment A was found to inhibit protein synthesis in mitoplasts to the same extent (approximately 80%) as the uncoupler carbonylcyanide p-trifluoromethoxyphenylhydrazone, but had no similar effect in lysed mitoplasts. Intact diphtheria toxin had no effect in either case. Fragment A was found to function as a potent uncoupler in isolated mitochondria and mitoplasts, inhibiting oxidative phosphorylation by approximately 80% at a concentration (2 micrograms fragment A/mg of protein) that did not inhibit protein synthesis. In contrast, intact toxin slightly increased the tightness of energy coupling in isolated mitoplasts. 125I-labelled intact diphtheria toxin was bound to mitoplasts to about the same extent as labelled fragment A. At concentrations which efficiently inhibited mitochondrial protein synthesis, fragment A had no effect on the intramitochondrial concentration of nicotinamide adenine dinucleotides, nor was it capable of ADP-ribosylating mitochondrial proteins, indicating that the well known enzymatic activity of fragment A is not involved in the observed effect in mitochondria. The results indicate that fragment A of diphtheria toxin inhibits protein synthesis in mitochondria and mitoplasts by inhibiting mitochondrial energy transduction. The detailed mechanism of the uncoupling effect and its possible significance in intact cells remain to be elucidated.

Animals↗
PubMed1980

Plasmids in Corynebacterium diphtheriae and diphtheroids mediating erythromycin resistance.

Plasmids were isolated from erythromycin-resistant Corynebacterium diphtheriae and skin coryneforms. Six erythromycin-resistant C. diphtheriae strains, isolated from cutaneous lesions, all contained a 9.5-megadalton (Mdal) plasmid. Loss of resistance was associated with the deletion of a 1-Mdal segment from the plasmid or, less frequently, with loss of the plasmid. Two erythromycin-resistant diphtheroids were isolated from similar skin lesions. One contained a 38-Mdal plasmid that was lost in the conversion to erythromycin susceptibiliy. The other diphtheroid contained a 30- and a 14-Mdal plasmid. Erythromycin-susceptible derivatives of this strain were not recovered. Restriction enzyme analysis indicated that the 9.5-Mdal plasmids in the C. diphtheriae strains are very similar, if not identical, and that each of the deleted plasmids has lost the same 1-Mdal segment. However, the restriction patterns of the plasmids in the two diphtheroids are not closely related to each other nor to the plasmids in the C. diphtheriae strains.

Corynebacterium diphtheriae↗
PubMed1982

Effect of polymers of L-lysine on the cytotoxic action of diphtheria toxin.

L-Lysine and poly(L-lysine) polymers of defined sizes were tested for their effect on diphtheria toxin-mediated cytotoxicity of Chinese hamster ovary cells. Poly(L-lysine)8-12 and poly(L-lysine)15 were protective, whereas lysine and lysine polymers of three and four residues were not. The protection by poly(L-lysine)8-12 occurred by affecting the initial toxin receptor interaction. Furthermore, poly(L-lysine)8-12 acted as a competitive inhibitor with an apparent dissociation constant of 6 X 10(-7) M. These observations are consistent with a previously proposed model (Proia et al., J. Biol. Chem. 256:4991-4997, 1981) in which (i) the cationic polyphosphate-binding site (P site) on the B fragment of diphtheria toxin interacts with a putative polyanionic binding site on the toxin receptor, and (ii) the protection of cells from diphtheria toxin by poly(L-lysine) and other polycationic molecules would be the result of the competition between these polycationic molecules and the cationic domain of the diphtheria toxin molecule for the polyanionic toxin-binding site on the cell surface receptor.

Animals↗
PubMed1984

Genetic and biochemical evidence for a siderophore-dependent iron transport system in Corynebacterium diphtheriae.

During growth under conditions of iron deprivation, Corynebacterium diphtheriae secreted a siderophore into the culture medium. This extracellular siderophore was necessary for rates of iron uptake at pH 8.0 by C. diphtheriae C7 and related strains. We isolated a mutant of C. diphtheriae C7(beta), strain HC6, which did not make the corynebacterial siderophore. Strain HC6 grew very poorly, even under high-iron conditions, and had a severe defect in iron transport. Both growth and iron uptake by strain HC6 were greatly stimulated by the corynebacterial siderophore. We used strain HC6 to develop a bioassay for the corynebacterial siderophore and to look for other potential siderophores for C. diphtheriae. Among the purified phenolate and hydroxamate siderophores tested, only aerobactin was able to stimulate the growth of strain HC6. Partial purification of the corynebacterial siderophore was achieved. The siderophore did not give positive reactions in the Arnow test for phenolates or the Csaky test for hydroxamates and may have a novel chemical structure.

Chromatography, High Pressure Liquid↗
PubMed1988

Synthesis and physicochemical and immunological characterization of pneumococcus type 12F polysaccharide-diphtheria toxoid conjugates.

A scheme for the synthesis and purification of conjugates, composed of the type 12F capsular polysaccharide of Streptococcus pneumoniae (Pn12F) and diphtheria toxoid, is described. The scheme is a modification of that described previously for the Vi capsular polysaccharide of Salmonella typhi, a linear homopolymer of N-acetylgalactoseaminouronic acid (S. C. Szu, A. L. Stone, J. D. Robbins, R. Schneerson, and J. B. Robbins, J. Exp. Med. 166:1510-1524, 1986). Pn12F is a branched-chain copolymer composed of a hexasaccharide repeating unit containing an aminouronic acid, N-acetylmannoseaminouronic acid (K. Leontein, B. Lindberg, and J. Lonngren, Can. J. Chem. 59:2081-2085, 1981). Sulfhydryl groups were introduced into Pn12F by forming an amide bond between cystamine and carboxyl groups of N-acetylmannoseaminouronic acid in the presence of a carbodiimide. The disulfide moiety of cystamine was reduced to form the cysteamine derivative of Pn12F which was, in turn, covalently bound to diphtheria toxoid by using the heterobifunctional linker N-succinimidyl-3-(2-pyridylthio)propionate. Unbound, high-molecular-weight Pn12F was removed from the conjugate by hydrophobic interaction chromatography through octyl Sepharose by using n-octyl-beta-D-glucopyranoside as the eluent. In young outbred mice, Pn12F did not elicit detectable serum antibodies. Pn12F-diphtheria toxoid, in contrast, elicited antibodies after two injections and had T-cell-dependent properties as evidenced by a response to priming and by its ability to elicit booster responses. This scheme seems applicable to the synthesis of conjugates with other capsular polysaccharides containing aminouronic acids. Clinical evaluation of Pn12F-diphtheria toxoid conjugates in healthy and in immunocompromised hosts is planned.

Animals↗