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Biomedical subjects

J Wilting

Publications and source records attributed to J Wilting.

At least 37 records · Page 2Linked to original sources
PubMed2000

The development of the avian vertebral column.

Segmentation of the paraxial mesoderm leads to somite formation. The underlying molecular mechanisms involve the oscillation of "clock-genes" like c-hairy-1 and lunatic fringe indicative of an implication of the Notch signaling pathway. The cranio-caudal polarity of each segment is already established in the cranial part of the segmental plate and accompanied by the expression of genes like Delta1, Mesp1, Mesp2, Ulicx-1, and EphA4 which are restricted to one half of the prospective somite. Dorsoventral compartmentalization of somites leads to the development of the dermomyotome and the sclerotome, the latter forming as a consequence of an epithelio-to-mesenchymal transition of the ventral part of the somite. The sclerotome cells express Pax-1 and Pax-9, which are induced by notochordal signals mediated by sonic hedgehog (Shh) and noggin. The craniocaudal somite compartmentalization that becomes visible in the sclerotomes is the prerequisite for the segmental pattern of the peripheral nervous system and the formation of the vertebrae and ribs, whose boundaries are shifted half a segment compared to the sclerotome boundaries. Sclerotome development is characterized by the formation of three subcompartments giving rise to different parts of the axial skeleton and ribs. The lateral sclerotome gives rise to the laminae and pedicles of the neural arches and to the ribs. Its development depends on signals from the notochord and the myotome. The ventral sclerotome giving rise to the vertebral bodies and intervertebral discs is made up of Pax-1 expressing cells that have invaded the perinotochordal space. The dorsal sclerotome is formed by cells that migrate from the dorso-medial angle of the sclerotome into the space between the roof plate of the neural tube and the dermis. These cells express the genes Msx1 and Msx2, which are induced by BMP-4 secreted from the roof plate, and they later form the dorsal part of the neural arch and the spinous process. The formation of the ventral and dorsal sclerotome requires directed migration of sclerotome cells. The regionalization of the paraxial mesoderm occurs by a combination of functionally Hox genes, the Hox code, and determines the segment identity. The development of the vertebral column is a consequence of a segment-specific balance between proliferation, apoptosis and differentiation of cells.

Animals↗
PubMed2000

Contribution of single somites to the skeleton and muscles of the occipital and cervical regions in avian embryos.

Controversy has surrounded the process of resegmentation of cervico-occipital somites. We have reinvestigated this topic by grafting single somites of quail embryos homotopically into chick embryos. Somites one to five contribute to the skull. Somites one and two contribute to the parasphenoid, which develops by direct ossification in a non-segmental fashion. All cartilaginous derivatives of the somites are segmental. Somite two forms a stripe of cells in the basioccipital, exoccipital and supraoccipital. Somites three to five give rise to the subsequent caudal parts of the basioccipital and exoccipital. Somite five forms the first motion segment including the occipital condyle, the cranial part of the atlas and the tip of the dens axis. Therefore, the border between head and neck is in the centre of somite five, and corresponds to the expression boundary of Choxb-3. Somite six forms the caudal part of the atlas and the cranial part of the axis. Somites two to eight all contribute to the cranio-cervical muscles with the exception of the Mm. rectus capitis dorsalis and ventralis and the M. biventer cervicis, which do not receive contributions from somite two. In contrast, the M. cucullaris capitis is exclusively formed by myogenic cells from somite two, which parallels its exclusive innervation by the accessory nerve. Our data confirm the segmental nature of the occiput, and show that resegmentation is a very regular process involving all except the four cranialmost somites. Except for somites one and two, all of the somites contribute to the muscles located at the appropriate levels.

Animals↗
PubMed2000

Dual origin and segmental organisation of the avian scapula.

Bones of the postcranial skeleton of higher vertebrates originate from either somitic mesoderm or somatopleural layer of the lateral plate mesoderm. Controversy surrounds the origin of the scapula, a major component of the shoulder girdle, with both somitic and lateral plate origins being proposed. Abnormal scapular development has been described in the naturally occurring undulated series of mouse mutants, which has implicated Pax1 in the formation of this bone. Here we addressed the development of the scapula, firstly, by analysing the relationship between Pax1 expression and chondrogenesis and, secondly, by determining the developmental origin of the scapula using chick quail chimeric analysis. We show the following. (1) The scapula develops in a rostral-to-caudal direction and overt chondrification is preceded by an accumulation of Pax1-expressing cells. (2) The scapular head and neck are of lateral plate mesodermal origin. (3) In contrast, the scapular blade is composed of somitic cells. (4) Unlike the Pax1-positive cells of the vertebral column, which are of sclerotomal origin, the Pax1-positive cells of the scapular blade originate from the dermomyotome. (5) Finally, we show that cells of the scapular blade are organised into spatially restricted domains along its rostrocaudal axis in the same order as the somites from which they originated. Our results imply that the scapular blade is an ossifying muscular insertion rather than an original skeletal element, and that the scapular head and neck are homologous to the 'true coracoid' of higher vertebrates.

Animals↗
PubMed2000

Sclerotomal origin of the ribs.

The somites of vertebrate embryos give rise to sclerotomes and dermomyotomes. The sclerotomes form the axial skeleton, whereas the dermomyotomes give rise to all trunk muscles and the dermis of the back. The ribs were thought to be ventral processes of the axial skeleton and therefore to be derived from the sclerotomes; however, recently a dermomyotomal origin of the distal rib (the costal shaft) was suggested, with only the proximal parts (head and neck of the rib) being of sclerotomal origin. We have re-investigated the development of the ribs in quail-chick chimeras and carried out three experimental series. (1) Single dermomyotomes and (2) single sclerotomes were grafted homotopically, and (3) the ectoderm overlying the unsegmented paraxial mesoderm was removed in the prospective thoracic region. We found that the cells of the dermomyotome gave rise to epaxial and hypaxial trunk muscles, dermis of the back and endothelial cells, but not to ribs. Cells of the sclerotome formed the axial skeleton and all parts of the ribs. Ablation of the ectoderm, which affects dermomyotome development, results in severe malformations of the ribs, probably due to disturbed interactions between dermomyotome and sclerotome. Our results strongly confirm the traditional view of the sclerotomal origin of the ribs.

Animals↗
PubMed2000

An avian model for studies of embryonic lymphangiogenesis.

Embryonic development of lymphatics (lymphangiogenesis) in recent years has rarely been studied experimentally. Using an avian model, we showed that both intra- and extra-embryonic blood vessels of chick and quail embryos are accompanied by lymphatics. The lymphatics of the chorioallantoic membrane (CAM) are drained by lymphatic trunks of the umbilicus and are connected to the posterior lymph hearts. Intra-embryonic lymphatics are drained via paired thoracic ducts into the jugulo-subclavian junction. The lymphatic endothelial cells are characterized by the expression of Vascular Endothelial Growth Factor Receptors (VEGFR) -2 and -3. Application of VEGF-C, the ligand of these two receptors, on the differentiated CAM, induces proliferation of lymphatic endothelial cells and formation of huge lymphatic sinuses. These lymphatics derive from pre-existing lymphatic endothelial cells, whereas, in early embryos lymphangioblasts are present in the mesenchyme. This phenomenon can be demonstrated by interspecific grafting experiments between chick and quail embryos. Together with the early lymph sacs, the lymphangioblasts form the embryonic lymphatic system. Our studies demonstrate the importance of lymphangioblasts and lymphangiogenic growth factors in embryonic lymphangiogenesis.

Animals↗
PubMed1999

Lymphangioblasts in the avian wing bud.

The development of the lymphatics has not yet been studied experimentally. Descriptive studies could not answer the question whether the lymphatics are exclusively derived by sprouts of the early embryonic lymph sacs, or whether lymphangioblasts in the mesenchyme contribute to the lymphatic system. We have studied the development of the lymphatics in quail-chick chimeras. In 6.5-day-old quail embryos, the endothelium of the jugulo-axillary lymph sac can be demonstrated with the QH1 antibody. In contrast to the jugular vein and the aorta, the lymph sac is irregularly shaped and does not possess a media of smooth muscle cells, and, the lymph sac endothelium starts to express the vascular endothelial growth factor receptor-3 (VEGFR-3). Cells of the quail paraxial mesoderm grafted into chick embryos integrate into the endothelium of the jugular lymph sac, strongly indicating the existence of lymphangioblasts. In the wing of 10-day-old quail embryos, VEGFR-3-positive lymphatics are accompanying all major blood vascular routes. On day 3.5 of development, that is about one day before the first occurrence of the jugulo-axillary lymph sac, we grafted distal wing buds of chick embryos homotopically into quail embryos. The chimeric wings were analyzed on day 10. The VEGFR-3 and QH1 double staining revealed that the lymphatics were formed by both chick and quail endothelial cells. This result shows that the lymphatics of the wing do not exclusively develop from sprouts of the lymph sacs, but also by recruitment of local lymphangioblasts.

Animals↗
PubMed1999

Embryonic lymphangiogenesis.

About 8-9 decades ago the development of embryonic lymphatics was studied intensively. Since then our knowledge has not considerably increased in this field, and it is still unknown whether lymphatics are derived by sprouting from veins, de novo from lymphangioblasts, or by both mechanisms. However, very recent studies have shown that the vascular endothelial growth factor-C (VEGF-C) is a highly specific lymphangiogenic growth factor. This raises new questions and perspectives. Here we will review the literature on embryonic lymphangiogenesis and lymphangiogenic growth factors. We also present a description of the pattern of the lymphatics of avian embryos with emphasis on lymph hearts. The avian embryo is highly suited for studies on lymphatics, because these can be demonstrated by injection methods, serial sectioning and in situ hybridization with VEGF-receptor-2 and -3 probes. The greatest advantage resides in the fact that the lymphatics of the chorioallantoic membrane are easily accessible for experimental studies.

Allantois↗
PubMed1998

The tachykinin NK1 receptor antagonist, RP67580, inhibits the bradykinin-induced rise in intracellular Ca2+ concentration in bovine pulmonary artery endothelial cells.

The bradykinin-induced rise in intracellular Ca2+ concentration ([Ca2+]i) and the bradykinin receptor involved in this response were characterized in bovine pulmonary artery endothelial cells. It was found that bradykinin induces an intracellular biphasic Ca2+ response, consisting of a transient peak followed by an elevated plateau phase. Both bradykinin and the bradykinin B1 receptor agonist, des-Arg9-bradykinin, induced a concentration-dependent increase in [Ca2+]i, but the bradykinin-induced rise was much greater. Moreover, the bradykinin-induced [Ca2+]i rise could be inhibited by the bradykinin B2 receptor antagonists, D-Arg0[Hyp3, Thi(5,8), D-Phe7]bradykinin and Hoe 140 (D-Arg[Hyp3, Thi5, D-Tic7, Oic8]bradykinin), but not by the bradykinin B1 receptor antagonist, des-Arg9-[Leu8]bradykinin. From these results it can be concluded that a bradykinin B2 receptor is involved in this response. Furthermore, we found that the tachykinin NK1 receptor antagonist, RP67580 ([imino 1 (methoxy-2-phenyl)-2 ethyl]-2 diphenyl 7,7 perhydroisoindolone-4 (3aR, 7aR)), and its negative enantiomer, RP68651 (2-[1-imino 2-(2 methoxy phenyl) ethyl] 7,7 diphenyl 4-perhydroisoindolone (3aS-7aS)), could inhibit the bradykinin-induced [Ca2+]i response, although no functional tachykinin NK1 receptors were found. Binding studies evidenced no binding of RP67580 or RP68651 to the bradykinin receptor. We conclude that RP67580 inhibits the bradykinin-induced rise in [Ca2+]i via a bradykinin B2 receptor-independent mechanism.

Animals↗
PubMed1998

Paracrine and autocrine regulation of vascular endothelial growth factor during tissue differentiation in the quail.

The expression of vascular endothelial growth factor (VEGF) has been described to coincide both temporally and spatially with angiogenesis suggesting a role as a paracrine stimulator of endothelial cells. We have used digoxigenin labelled RNA probes to VEGF and the VEGF receptor-2 (Quek1) to investigate the relationship between VEGF expression and vascular events in quail embryos from day 1 to 13 of incubation. Furthermore, the effect of exogenously applied VEGF was studied in day 4 quail embryos using polyclonal anti-VEGF antibodies. Expression of VEGF mRNA was observed in day 1 and 2 embryos in regions of active angiogenesis and hemangiopoiesis. VEGF mRNA expression was found at high levels in the ventral aspect of the neural tube and Quek1 mRNA expression in the accompanying endothelial cells of day 3 embryos, suggesting a function in brain angiogenesis. However, in the neural tube, thyroid gland and cartilaginous skeleton VEGF mRNA was expressed at least 1 day before the ingrowth of vessels, suggesting that additional mechanisms are involved in control of angiogenesis. This is supported by the observation that application of VEGF165 into the midbrain induced dilatation of perineural vessels, while the intraneural vessels remained almost unaffected. Expression of VEGF mRNA was also observed at high levels in podocytes during all stages, indicative of its importance in glomerular development and function. The results of the present study indicate that as angiogenesis occurred in other tissues and organs (day 13 metanephros, dorsal third of the day 7 neural tube, skeletal muscle, and many mesodermal compartments), there was concurrent paracrine expression of VEGF mRNA and Quek1 mRNA. One noteable exception was the hepatocytes of the developing liver which appeared to remain VEGF-negative throughout the study. However, a small number of endothelial cells within liver sinuses, and additionally within the kidney and the elastic arteries, expressed VEGF mRNA. These results suggest that VEGF may also act as an autocrine mediator of angiogenesis, possibly as a result of localised tissue hypoxia.

Animals↗
PubMed1998

Automated evaluation of angiogenic effects mediated by VEGF and PlGF homo- and heterodimers.

The effects of growth factors on the blood vessel pattern of chick chorioallantoic membrane (CAM) were assessed with a fast and automated method (extended counting method, XCM; Sandau, 1996) that measures complexity, without assumptions about a fractal structure. XCM is a reliable measure of complexity not only in theory but also in practice: (1) it is robust with respect to thresholding; (2) it shows reduced variance due to pattern translation and rotation; (3) its properties come close to requirements of fractal geometry. It hence is superior to established fractal methods for distinguishing effects induced by various isoforms of vascular endothelial growth factor (VEGF121 and VEGF165), placenta growth factor (PlGF) isoforms, and control treatment. We here show that VEGF homo- and heterodimers and VEGF121/PlGF1 heterodimers increase vascular complexity, whereas PlGF1 and PlGF2 are not effective. PlGF1 and VEGF121 did not mutually influence each other when applied in adjacent fields on the same CAM. Since blood vessels in the CAM originate via nonfractal growth processes, their growth should be analyzed accordingly.

Amnion↗
PubMed1998

Influence of Clostridium botulinum C2 toxin on Fc epsilonRI-mediated secretion and tyrosine phosphorylation in RBL cells.

We studied the effects of the binary Clostridium botulinum C2 toxin on stimulated [3H]serotonin release and protein tyrosine phosphorylation in RBL 2H3 hm1 cells. Actin was specifically ADP-ribosylated by C2 toxin in intact cells resulting in a 2-3 fold increase in antigen- or calcium ionophore (A23187)-induced degranulation. The effects of C2 toxin were time- and concentration-dependent. Toxin treatment, which dramatically changes the morphology of RBL cells, was not sufficient to induce mediator release in the absence of activators of secretion. Antigen- and A23187-stimulated tyrosine phosphorylation of 60-80 kDa and 110-120 kDa proteins was reduced or blocked after C2 toxin incubation. Treatment of RBL cells with the tyrosine phosphatase inhibitor pervanadate reversed the inhibitory effect of C2 toxin on stimulated protein tyrosine phosphorylation indicating activation of phosphatases by C2 toxin. The data indicate that disassembly of the actin cytoskeleton by C2 toxin facilitates Fc epsilonRI-mediated signal-secretion coupling and suggest a role of the actin cytoskeleton in phosphatase regulation in RBL cells.

Actins↗
PubMed1998

Platelet-derived growth factor-B induces transformation of fibrocytes into spindle-shaped myofibroblasts in vivo.

Platelet-derived growth factor (PDGF) has a targeted activity on mesenchymal cells, but the in vivo effects of PDGF are not well understood. We have applied about 3 microg of PDGF-A and PDGF-B on the differentiated chorioallantoic membrane (CAM) of 13-day-old chick embryos. After 1-3 days, specimens were evaluated macroscopically, histologically with semi- and ultrathin sections, and immunohistologically with antibodies against smooth muscle alpha-actin (alphaSMA), desmin, and fibronectin (FN). Proliferation studies were performed according to the 5-bromo-2-deoxyuridine (BrdU)/anti-BrdU method. We did not observe effects of PDGF-A. PDGF-B induced proliferation of fibrocytes and their transformation into myofibroblasts. Bundles of spindle-shaped myofibroblasts accumulated beneath the chorionic epithelium. These cells were strongly positive for alphaSMA and FN, but negative for desmin. They possessed a well developed rough endoplasmic reticulum and bundles of microfilaments anchoring in the cell membrane. Our results suggest that PDGF-B is a "transforming" growth factor with important functions during formation of granulation tissue which are closely comparable to the effects of the PDGF-B-like protein of simian sarcoma virus. PDGF-B also induced vascular alterations in the CAM, which, however, appeared to be a secondary effect. While the intra-chorionic capillaries were lost, an accumulation of small vessels positive for alphaSMA was observed. This indicates a function for PDGF-B during segregation of main vessels from a primary vascular plexus.

Actins↗
PubMed1998

Segmentation of the vertebrate body.

The segmental character of the vertebrate body wall is reflected by metamerically arranged tissues that are patterned during embryonic life as a consequence of somite formation, compartmentalization and differentiation. The somites bud off the paraxial mesoderm in a cranio-caudal sequence and are compartmentalized by local signals from adjacent structures. These signals may be mediated by diffusible substances such as Sonic hedgehog (Shh), Wnts and Bone morphogenetic protein (BMPs) or by cell-cell interactions via membrane-bound receptors and ligands such as Delta and Notch. Compartmentalization of the somites and their derivatives is reflected by the differential expression of developmental regulatory genes such as Pax-1, 3, 7 and 9, MyoD, paraxis, twist and others. Secondary segmentation is imposed upon other tissues, such as blood vessels and nerves, by the rearrangement and regionalization of the somitic derivatives, especially the sclerotome. Early cranio-caudal identity is determined by the expression of different Hox genes. Finally, fusion of segmental anlagen occurs to form segment-overbridging skeletal elements and muscles. The expression of homologous genes indicates that the process of segmentation in vertebrates and invertebrates is homologous, derived by descent from a common ancestor.

Animals↗
PubMed1997

Thermodynamic analysis of the interaction between a bactericidal antibody and a PorA epitope of Neisseria meningitidis.

An antibody-peptide model system was used to study the binding characteristics between a bactericidal antibody (MN12H2) and the P1. 16 epitope of class 1 outer membrane protein PorA of Neisseria meningitidis by means of a thermodynamic approach. A series of four linear peptides and three "head-to-tail" cyclic peptides (with ring sizes of 9, 15 and 17 amino acids) were synthesized and evaluated as ligands. The peptides contain a fluorescein label and the core determinant amino acid sequence TKDTNNN (residues 180-186) of the PorA P1.16 epitope of meningococcal strain H44/76. Thermodynamic data of the binding of the peptide homologs of the epitope by MN12H2 were assessed by measuring affinity constants (Ka) over a temperature range of 4-55 degrees C, using fluorescence spectroscopy. Curvilinear plots of ln Ka versus T (K) revealed strong temperature dependencies of enthalpy (DeltaH) and entropy (DeltaS). The Gibbs free energy change (DeltaG) was only weakly temperature dependent. The large negative enthalpy value indicated the importance of polar interactions in the binding of both linear and cyclic peptides by MN12H2. Sturtevant's analysis of the thermodynamic parameters showed large unfavorable vibrational contributions to the binding for all linear peptides [Sturtevant, J. M. (1977) Proc. Natl. Acad. Sci.U.S.A. 74, 2236-2240]. The large hydrophobic contribution compensating these vibrational modes was partially attributed to aspecific interaction of the fluorescein label with the antibody. Binding of MN12H2 to conformationally restricted epitope sequences was characterized by a dramatic reduction in the size of unfavorable vibrational components of the thermodynamic parameters. Substitution of individual charged amino acids of the P1.16 epitope sequence revealed that aspartate-182 was essential for the binding. The pH profile observed for the MN12H2-peptide complexes with a midpoint pH of approximately 8.5 suggests a positively charged histidine from the antibody binding site to be involved in a charge interaction with Asp-182. These findings are consistent with the results from the crystal structure of the Fab fragment of MN12H2 in complex with a linear fluorescein-conjugated peptide homolog of the P1.16 epitope [van den Elsen et al. (1997) Proteins (in press)], thereby identifying the basis of an increased incidence of endemic disease in England and Wales since 1981 caused by a mutant meningococcal strain.

Animals↗
PubMed1997

VEGF and VEGF-C: specific induction of angiogenesis and lymphangiogenesis in the differentiated avian chorioallantoic membrane.

The lymphangiogenic potency of endothelial growth factors has not been studied to date. This is partially due to the lack of in vivo lymphangiogenesis assays. We have studied the lymphatics of differentiated avian chorioallantoic membrane (CAM) using microinjection of Mercox resin, semi- and ultrathin sectioning, immunohistochemical detection of fibronectin and alpha-smooth muscle actin, and in situ hybridization with VEGFR-2 and VEGFR-3 probes. CAM is drained by lymphatic vessels which are arranged in a regular pattern. Arterioles and arteries are accompanied by a pair of interconnected lymphatics and form a plexus around bigger arteries. Veins are also associated with lymphatics, particularly larger veins, which are surrounded by a lymphatic plexus. The lymphatics are characterized by an extremely thin endothelial lining, pores, and the absence of a basal lamina. Patches of the extracellular matrix can be stained with an antibody against fibronectin. Lymphatic endothelial cells of differentiated CAM show ultrastructural features of this cell type. CAM lymphatics do not possess mediae. In contrast, the lymphatic trunks of the umbilical stalk are invested by a single but discontinuous layer of smooth muscle cells. CAM lymphatics express VEGFR-2 and VEGFR-3. Both the regular pattern and the typical structure of these lymphatics suggest that CAM is a suitable site to study the in vivo effects of potential lymphangiogenic factors. We have studied the effects of VEGF homo- and heterodimers, VEGF/PlGF heterodimers, and PlGF and VEGF-C homodimers on Day 13 CAM. All the growth factors containing at least one VEGF chain are angiogenic but do not induce lymphangiogenesis. PlGF-1 and PlGF-2 are neither angiogenic nor lymphangiogenic. VEGF-C is the first lymphangiogenic factor and seems to be highly chemoattractive for lymphatic endothelial cells. It induces proliferation of lymphatic endothelial cells and development of new lymphatic sinuses which are directed immediately beneath the chorionic epithelium. Our studies show that VEGF and VEGF-C are specific angiogenic and lymphangiogenic growth factors, respectively.

Actins↗
PubMed1997

On the interaction between a bactericidal antibody and a PorA epitope of Neisseria meningitidis in outer membrane vesicles: a competitive fluorescence polarization immunoassay.

This paper describes a method for determining the affinity constant (Ka) of the binding between an antibody Fab fragment and a membrane-embedded protein epitope under equilibrium conditions. Monoclonal antibody MN12H2, directed against outer membrane protein PorA of Neisseria meningitidis, is used in a competitive fluorescence polarization assay with a cyclic peptide-fluorescein conjugate as a tracer antigen. Displacement experiments with PorA-containing and PorA-deficient meningococcal outer membrane vesicles revealed highly specific binding of MN12H2 Fab to the membrane-embedded PorA P1.16 epitope with Ka of 1.5 x 10(8) M-1.

Amino Acid Sequence↗
PubMed1997

Bactericidal antibody recognition of a PorA epitope of Neisseria meningitidis: crystal structure of a Fab fragment in complex with a fluorescein-conjugated peptide.

Class 1 outer membrane protein PorA of Neisseria meningitidis is a vaccine candidate against bacterial meningitis. Antibodies against PorA are able to induce complement-mediated bacterial killing and thereby play an important role in protection against meningococcal disease. Bactericidal antibodies are all directed against variable regions VR1 and VR2 of the PorA sequence, corresponding to loops 1 and 4 of a two-dimensional topology model of the porin with eight extracellular loops. We have determined the crystal structure to 2.6 A resolution of the Fab fragment of bactericidal antibody MN12H2 against meningococcal PorA in complex with a linear fluorescein-conjugated peptide TKDTNNNL derived from the VR2 sequence of sero-subtype P1.7,16 (residues 180-187) from meningococcal strain H44/76. The peptide folds deeply into the binding cavity of the Fab molecule in a type I beta-turn, with the minimal P1.16 epitope DTNNN virtually completely buried. The structure reveals H-bonds and van der Waals interactions with all minimal epitope residues and one essential salt bridge between Asp-182 of the peptide and His-31 of the MN12H2 light chain. The key components of the recognition of PorA epitope P1.16 by bactericidal antibody MN12H2 correspond well with available thermodynamic data from binding studies. Furthermore, they indicate the structural basis of an increased endemic incidence of infection by group B meningococci in England and Wales since 1981 associated with the occurrence of an Neisseria meningitidis escape mutant (strain-MC58). The observed three-dimensional conformation of the peptide provides a rationale for the development of a synthetic peptide vaccine against meningococcal disease.

Amino Acid Sequence↗