A broadly cross-reactive monoclonal antibody against an epitope on the n-terminus of meningococcal fHbp.

Meningococcal factor H binding protein (fHbp) is an important vaccine antigen for prevention of disease caused by capsular group B strains. The protein has been sub-classified into three variant groups. Most anti-fHbp antibodies are variant group-specific and recognize epitopes on the C-terminal domain.

Monoclonal antibodies to meningococcal factor H binding protein with overlapping epitopes and discordant functional activity.

Background: Meningococcal factor H binding protein (fHbp) is a promising vaccine candidate. Anti-fHbp antibodies can bind to meningococci and elicit complement-mediated bactericidal activity directly. The antibodies also can block binding of the human complement down-regulator, factor H (fH).

Combined roles of human IgG subclass, alternative complement pathway activation, and epitope density in the bactericidal activity of antibodies to meningococcal factor h binding protein.

Meningococcal vaccines containing factor H binding protein (fHbp) are in clinical development. fHbp binds human fH, which enables the meningococcus to resist complement-mediated bacteriolysis. Previously, we found that chimeric human IgG1 mouse anti-fHbp monoclonal antibodies (MAbs) had human complement-mediated bactericidal activity only if the MAb inhibited fH binding.

Complement-mediated bactericidal activity of anti-factor H binding protein monoclonal antibodies against the meningococcus relies upon blocking factor H binding.

Binding of the complement-downregulating protein factor H (fH) to the surface of the meningococcus is important for survival of the organism in human serum. The meningococcal vaccine candidate factor H binding protein (fHbp) is an important ligand for human fH. While some fHbp-specific monoclonal antibodies (MAbs) block binding of fH to fHbp, the stoichiometry of blocking in the presence of high serum concentrations of fH and its effect on complement-mediated bactericidal activity are unknown.

Somatic diversity in CDR3 loops allows single V-genes to encode innate immunological memories for multiple pathogens.

The human Ab response to many common pathogens is oligoclonal, with restricted usage of Ig V-genes. Intriguingly, the IGVK3-11 and IGVH3-30 V-genes are repeatedly paired in protective Abs against the 23F polysaccharide of Streptococcus pneumoniae, as well as against the gB envelope protein of human CMV, where germline-encoded amino acids make key contacts with the gB protein. We constructed IgGs encoded by the germline IGVK3-11 and IGVH3-30 V-genes together with DNA encoding the respective CDR3 regions of the L chain and H chain found in a hypermutated anti-23F Ab.

Domain specificity of the human antibody response to Bacillus anthracis protective antigen.

Protective antigen (PA) is the cell surface recognition moiety of the Bacillus anthracis A-B toxin system, and the active immunogenic component in the currently licensed human anthrax vaccine (BioThrax, or AVA). The serum antibody response to the PA protein is polyclonal and complex both in terms of the antibody combining sites utilized to bind PA and the PA-associated epitopes recognized. We have cloned, sequenced, and expressed a large panel of PA-specific human monoclonal antibodies from seven AVA-immunized donors.

Paratope diversity in the human antibody response to Bacillus anthracis protective antigen.

The active component of the licensed human anthrax vaccine (BioThrax, or AVA) is a Bacillus anthracis toxin known as protective antigen (PA). Second generation anthrax vaccines currently under development are also based on a recombinant form of PA. Since the current and future anthrax vaccines are based on this toxin, it is important that the immunobiology of this protein in vaccinated humans be understood in detail.

Codon insertion and deletion functions as a somatic diversification mechanism in human antibody repertoires.

Unlabelled: It has been suggested that codon insertion and/or deletion may represent a mechanism that, along with hypermutation, contributes to the affinity maturation of antibodies. We used repertoire cloning to examine human antibodies directed against 3 carbohydrate antigens and 1 protein antigen for the presence of such modifications. We find that both the insertion and deletion of codons occur frequently in antigen-specific responses following vaccination.

Somatic hypermutation and diverse immunoglobulin gene usage in the human antibody response to the capsular polysaccharide of Streptococcus pneumoniae Type 6B.

Combinatorial cloning and expression library analysis were used to determine the expressed human antibody repertoire specific for the capsular polysaccharide (PS) of Streptococcus pneumoniae serotype 6B. Sequence analysis of 55 6B-specific antibody Fab fragments isolated from six vaccinated donors reveal that different individuals used a variety of heavy and light chain germ line variable (V) region genes to form pneumococcal capsular PS (PPS) 6B-specific paratopes. Within each donor, however, the response was more restricted, with five of the six donors using at most one or two gene pairs to form combining sites.

Correlation of antigenic epitope and antibody gene usage in the human immune response to Streptococcus pneumoniae type 23F capsular polysaccharide.

The human antibody response to the capsular polysaccharide of Streptococcus pneumoniae type 23F is predominated by antibodies which express either VkappaL6 or VkappaA23 light chain genes. In this report, we demonstrate that the antigenic epitopes recognized by these two families can be differentiated based on their specificity for the hapten l-rhamnose, a constituent sugar of the bacterial capsule polymer. The VkappaL6 family utilizes light chains with an unusually long third complementarity-determining region.

Molecular ontogeny of the human antibody repertoire to the Haemophilus influenzae type B polysaccharide: expression of canonical variable regions and their variants in vaccinated infants.

A structurally conserved antibody combining site, encoded by the IGH V3-23 and kappa A2 variable (V) region gene segments, predominates the adult immune response to the Haemophilus influenzae type b (Hib) capsular polysaccharide (PS). This site has been elevated to canonical status based upon its relative molecular uniformity and prevalence in adults. To date, no studies have examined the primary structure of Hib PS-specific antibodies in young infants, who are the primary targets of Hib vaccination.

Recurrent variable region gene usage and somatic mutation in the human antibody response to the capsular polysaccharide of Streptococcus pneumoniae type 23F.

Combinatorial cloning and expression library analysis were used to isolate human antibody Fab fragments specific for the capsular polysaccharide of Streptococcus pneumoniae serotype 23F. Thirty 23F-specific Fabs were isolated from seven vaccinated donors, and the sequences of the heavy (H)- and light (L)-chain variable regions were determined. All individuals utilized either the Vkappa A23 L chain, the Vkappa L6 L chain, or both chains in forming the 23F-specific combining site.