Protection against infection with Neisseria meningitidis group B serotype 2b by passive immunization with serotype-specific monoclonal antibody

Development and application of monoclonal antibodies for the detection of cell infecting mycoplasmas

Two hybridoma cell lines producing monoclonal antibodies (MAbs) to mycoplasmas were established by fusion of mouse myeloma and spleen cells obtained from mice immunized with whole cell Mycoplasma pneumoniae antigens. The MAbs designated as MYC-4 and MYC-9 bound to a single M. pneumoniae protein band with approximate molecular weights of 150,000. In dot-EIA both MAbs reacted with ten Mycoplasma spp., two serovars of Ureaplasma urealyticum and Acholeplasma laidlawii. The MAbs have great potential to be used as an antibody probe for the rapid screening of cell cultures and hybridomas for mycoplasmal contamination.

Sequence of the structural gene (rmpM) for the class 4 outer membrane protein of Neisseria meningitidis, homology of the protein to gonococcal protein III and Escherichia coli OmpA, and construction of meningococcal strains that lack class 4 protein

The structural gene (rmpM) of the class 4 outer membrane protein of Neisseria meningitidis has been cloned and sequenced. The derived amino acid sequence reveals a 218-amino-acid protein following a 22-amino-acid signal peptide. The protein shows 94.2% homology with protein III of Neisseria gonorrhoeae and shares its two potential disulfide loops. The protein also shares limited homology with Escherichia coli OmpA. N. gonorrhoeae protein III has been shown to elicit blocking antibodies that prevent the killing of serum-resistant strains by immune sera (P. A. Rice, H. E. Vayo, M. R. Tam, and M. S. Blake, J. Exp. Med. 164:1735-1748, 1986). The very close homology of meningococcal class 4 protein with gonococcal protein III suggests that meningococcal outer membrane preparations containing class 4 protein may similarly stimulate blocking antibodies. In order to investigate the role of the class 4 protein in the pathogenesis of meningococcal infection, we have used an erythromycin resistance gene in developing two meningococcal strains that lack class 4 protein.

Effectiveness of natural and synthetic complexes of porin and O polysaccharide as vaccines against Brucella abortus in mice

A single vaccination of mice with a complex of porin and smooth lipopolysaccharide (porin-S-LPS) extracted from virulent Brucella abortus 2308 provided significant protection (P less than 0.01 to P less than 0.001) against challenge with the same strain, equivalent to that achieved by vaccination with living attenuated B. abortus 19. The porin-S-LPS vaccine given without adjuvant or in several adjuvants (trehalose dimycolate and muramyl dipeptide; the pluronic polymer L-121 and muramyl dipeptide; or complexed with Quil A in immunostimulating complexes) provided equivalent protection. In contrast, one vaccination with porin complexed with rough LPS (porin-R-LPS) from a rough mutant of strain 2308 provided no protection with any adjuvant tested. In one experiment, two inoculations with the porin-R-LPS resulted in a low level of protection, probably owing to priming of the animals for production of O-polysaccharide-specific antibodies. However, one vaccination with rough-strain porin covalently bound to purified O polysaccharide conferred protection equal to that obtained with natural complexes of porin-S-LPS or with living strain 19. A synthetic vaccine containing long chains of O polysaccharide was more effective than one prepared with short chains. Protective vaccines caused the formation of increased concentrations of circulating O-polysaccharide-specific antibodies, although there were individual exceptions to the quantitative association between O-polysaccharide-specific antibodies and protection. Antibodies specific for porin or R-LPS were found in negligible quantities in vaccinated mice. These results provide additional evidence that the O polysaccharide will constitute an essential component of an effective subcellular vaccine against B. abortus and that O-polysaccharide-specific antibodies play an important role in protective immunity in brucellosis.

Restoration of antibody binding to blotted meningococcal outer membrane proteins using various detergents

Restoration of IgG antibody binding to heat-denatured meningococcal outer membrane proteins has been studied on immunoblots with a series of 14 detergents. Nitrocellulose strips with the blotted proteins were incubated with the detergents and sera from human volunteers vaccinated with meningococcal membrane proteins. Zwitterionic and ionic detergents, containing substituted quarternary ammonium or amino groups with a minimum of 10 C atoms in the alkyl chain, restored the antigenicity of the serotype-specific class 2 porin protein. The concentrations of the Zwittergent detergents necessary for activation decreased with increasing alkyl chain length of the homologues. Only zwitterionic detergents renatured the class 1 protein. Both proteins were weakly antigenic in the presence of the nonionic detergents Triton X-100 and Tween 20. Meningococcal lipopolysaccharide restored antibody binding to the porin, but not to the class 1 protein. Similar concentrations of lipopolysaccharides from two other gram-negative bacteria had no effect.

Effects of serum carrier proteins on the growth of pathogenic neisseriae with heme-bound iron

The pathogenic neisseriae can use free heme and hemoglobin as an essential source of iron (Fe) for growth in vitro, but it is unknown whether they can utilize heme bound to human hemopexin or to human serum albumin, or hemoglobin bound to haptoglobin. We found that neither Neisseria meningitidis nor Neisseria gonorrhoeae used bound heme, but bound hemoglobin was used as an Fe source by two meningococcal strains and one gonococcal strain. A second gonococcal strain, previously shown to use free hemoglobin poorly or not at all, also did not grow with hemoglobin-haptoglobin complex as an Fe source. These observations suggest that hemoglobin might act as an Fe source in vivo for many pathogenic neisseriae even when in complexed (bound) form, but heme probably would not support growth in vivo if bound to serum carrier proteins.

Human immunoglobulin G subclass immune response to outer membrane antigens in meningococcal group B vaccine

The immunoglobulin G (IgG) subclass distribution of antibodies against the major outer membrane proteins from serotype 2a Neisseria meningitidis in human vaccinees was studied by immunoblotting. The volunteers received two doses of a noncovalent complex of group B polysaccharide and outer membrane material from the same meningococcal strain. Six weeks after the first vaccination the antibodies mounted against the class 1 and 5 proteins belonged mainly to the IgG1 and IgG3 subclasses. However, the binding of IgG3 to the class 5 proteins decreased markedly in serum samples taken after 25 weeks. Antibody binding to the serotype-specific class 2 protein was dependent on renaturation of the antigen by a dipolar ionic detergent (R. E. Mandrell and W. D. Zollinger, J. Immunol. Methods 67:1-11, 1984). The immune response against this protein showed more individual variation and consisted of IgG1 or IgG3 or both, often combined with IgG4.

Immunoresponses to Neisseria meningitidis epitopes: immunomodulation by meningococcus B acts on more than one meningococcal surface epitope

Neisseria meningitidis group B strain M986 (serotypes 2a, 7) (NMB) elicits a specific primary antiphosphorylcholine immune response in mice but not a secondary response. The ability of other serotype and serogroup meningococci to induce similar primary responses in mice was studied, as was the immunogenicity of trinitrophenyl coupled NMB (TNP-NMB) in primary and secondary antitrinitrophenyl responses. Except for NMB, all other strains tested (three serogroup B and one serogroup A meningococcal strains) were found to be very poor phosphorylcholine immunogens. TNP-NMB, however, though proving to be a very good TNP antigen, was only a weak phosphorylcholine antigen. Priming NBF1 female mice with TNP-NMB one month or more before challenging them with the same antigen induced a strong depression of anti-TNP response in the subsequent challenge. However, this effect was not observed with Xid NBF1 male mice. Furthermore, priming mice with NMB weakly affected the anti-TNP response, but greatly depressed the antiphosphorylcholine response, after TNP-NMB challenge. In addition, whereas apparently only one TNP-specific B cell subpopulation was responding in unprimed mice challenged simultaneously with TNP-NMB and TNP-Ficoll (non-additive response), priming mice with NMB appeared to facilitate the independent activation of two different TNP-specific B cell subpopulations (additive response).

Sensitivity and specificity of enzyme immunofiltration and DNA hybridization for the detection of HCMV-infected cells

The sensitivity and specificity of enzyme immunofiltration and DNA hybridization were compared in human cytomegalovirus (HCMV) (AD 169)-infected MRC-5 cells. The enzyme immunofiltration was carried out on glass fiber filters in microplates, using an HCMV (AD 169) monoclonal antibody and a peroxidase conjugate. The DNA hybridization was carried out with a microfiltration apparatus, using a 32P-labelled HCMV (AD 169) Eco R1 D fragment probe. The sensitivities of enzyme immunofiltration and DNA hybridization were 1.82 X 10(3) and 1.13 X 10(3) infected cells, respectively. Both methods were highly specific, but enzyme immunofiltration was faster and simpler.

Rapid diagnosis of severe Haemophilus influenzae serotype b infections by monoclonal antibody enzyme immunoassay for outer membrane proteins

A highly sensitive and specific enzyme immunoassay (EIA) for the detection of Haemophilus influenzae serotype b antigens in body fluids and broth cultures was developed, with a polyclonal antibody directed against polyribose phosphate as the solid-phase reagent and a biotinylated monoclonal antibody directed against H. influenzae type b outer membrane protein as the liquid-phase reagent. H. influenzae type b antigens could be detected in broth cultures containing as little as 50 organisms per ml. The sensitivity and specificity of this system were compared with those of two commercial kits and counterimmunoelectrophoresis. The overall detection of H. influenzae type b antigens in clinical specimens collected from children infected with H. influenzae type b was as follows: with Phadebact, 86 and 86% in cerebrospinal fluid and urine specimens, respectively; with Bactigen, 86, 80, and 92%, with counterimmunoelectrophoresis, 78, 73, and 75%, and with biotin-avidin EIA, 100, 100, and 100% for cerebrospinal fluid, serum, and urine specimens, respectively. In the biotin-avidin EIA, no positive reactions were noted in specimens collected from patients infected with other bacteria or from patients without evidence of bacterial infection, whereas false-positive reactions were found by counterimmunoelectrophoresis and the commercial kits. These results suggest that this monoclonal antibody reacting with the outer membrane protein is more specific and sensitive than the conventional methods using polyclonal antisera for the detection of H. influenzae type b antigens during severe infections in children.

A human monoclonal macroglobulin with specificity for alpha(2----8)-linked poly-N-acetyl neuraminic acid, the capsular polysaccharide of group B meningococci and Escherichia coli K1, which crossreacts with polynucleotides and with denatured DNA

We have described an IgM antibody from a patient with macroglobulinemia specifically reacting with poly-alpha(2----8)N-acetyl neuraminic acid (NeuNAc) the capsular polysaccharide of two important human pathogens, group B meningococcus and E. coli K1. This antibody has a narrowly defined specificity in its interactions with polysaccharides, being unable to bind poly-alpha(2----9)NeuNAc or alternating poly-alpha(2----8)alpha(2----9)NeuNAc. However, it shows interesting crossreactivity with seemingly unrelated polynucleotides and denatured DNA, supporting the hypothesis that charged groups with a given spacing may determine the specificity of antigen-antibody interactions on otherwise dissimilar molecular structures. Despite the crossreactivity with denatured DNA and polynucleotides, the antibody does not appear to have adverse effects in the patient. The antibody protects newborn rats against E. coli K1 infection, as well as the standard horse antiserum H46, and one would expect it to prove useful in humans as an adjunct to antibiotic therapy in infections with group B meningococcus and E. coli K1. We have attempted to clone the antibody-producing cells from peripheral blood, and have shown that the relevant cells are present and can be cultured.

High yield monoclonal antibody production in ascites

BALB/c males were mated with Swiss Webster/HPB females to produce a first generation cross. Hybridoma cells derived from fusing SP2/0 myeloma cells and histocompatible spleen cells were injected intraperitoneally into these mice to induce formation of ascites tumors and production of ascitic fluid containing large quantities of monoclonal antibody. Mice, 80 days old weighing between 28 g to 35 g, were treated with 0.5 ml of pristane 18 days before inoculation of 3.2 X 10(6) hybridoma cells. The first generation crosses, (BALB/c male X SW/HPB female)F1, produced up to 4 times more ascitic fluid of equally high antibody level over a longer period compared to the BALB/c parent. This first generation cross is a cost effective means for monoclonal antibody production.