Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Epitopes”

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 1,153 records · Page 64Linked to original sources
PubMed2006

Positive reactions on Western blots do not necessarily indicate the epitopes on antigens are continuous.

Epitope mapping (identification of an antigenic site recognized by an antibody) is an important component of vaccine development and immunological assays. It is widely accepted that in Western blots, antibodies react exclusively with continuous epitopes: discontinuous epitopes are assumed to be irreversibly destroyed by electrophoresis under the denaturing conditions used for sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Here, we demonstrate that the epitopes recognized by four different monoclonal antibodies were identified as discontinuous epitopes when characterized by radioimmunoprecipitation assays and enzyme-linked immunosorbent assays, yet each of these antibodies reacted with the corresponding antigen on Western blots. Reaction on Western blots may be due to epitope renaturation during or after the transfer of the protein to a membrane. Therefore, positive reactions on Western blots do not necessarily indicate that epitopes are continuous and this caveat should be kept in mind while characterizing them.

Antibodies, Monoclonal↗
PubMed1993

Structure of the murine rab3A gene: correlation of genomic organization with antibody epitopes.

Rab3A is a neuronal low-molecular-mass GTP-binding protein that is modified post-translationally by two geranylgeranyl groups and specifically targeted to synaptic vesicles. We have now cloned and characterized the murine gene coding for rab3A. With a size of less than 8 kb including the promoter, the rab3A gene is relatively small. It contains five exons, the first of which is non-coding. The organization of the rab3A coding sequence into exons in the gene is different from that of ras proteins, the only other low-molecular-mass GTP-binding proteins with currently characterized gene structures. Nevertheless, the intron placement in the primary structure of rab3A may be indicative of a domain division of the protein, since each coding exon contains one of the four major conserved rab protein sequence motifs. The epitopes of monoclonal and polyclonal antibodies to rab3A were mapped with the hypothesis that antibody epitopes might represent distinct exposed protein domains and correlate with exon structures. Two monoclonal antibodies, named 42.1 and 42.2, were found to recognize epitopes with a different degree of conservation between different rab3 isoforms. These epitopes were mapped to relatively short amino acid sequences corresponding to exons 4 and 5 respectively, whereas a polyclonal antibody recognized a complex epitope that required the presence of intact rab3A. Comparison of the sequence of rab3A with that of ras, whose crystal structure has been determined, revealed that the epitopes for the monoclonal antibodies correspond to regions in ras that are highly exposed. Taken together, these results suggest that exons 4 and 5 at least represent distinct exposed protein domains that also form major natural epitopes in rab3A.

Amino Acid Sequence↗
PubMed2004

Characterization of the anti-BP180 autoantibody reactivity profile and epitope mapping in bullous pemphigoid patients.

Bullous pemphigoid is a subepidermal bullous disease of skin and mucosae associated with autoantibodies to BP180. To characterize the humoral response to BP180, we generated a random BP180 epitope library displayed on lambda bacteriophage. After validation of the library by epitope mapping of three BP180-specific monoclonal antibodies, 15 novel or known BP180 epitopes were identified using 10 bullous pemphigoid serum samples. Fifty-seven bullous pemphigoid and 81 control sera were then assayed against the selected epitopes. Thirty-one out of 57 (54%) bullous pemphigoid sera reacted with at least an additional antigenic site other than the NC16A, within the extracellular (37%) and intracellular (28%) domains of BP180. In addition, the reactivity with extracellular epitopes of BP180 contained within the residue stretches 508-541 and 1331-1404 appeared to be related to the presence of both skin and mucosal involvement. Finally, a preliminary analysis of the epitope pattern in the disease course indicated that bullous pemphigoid patients exhibit a specific reactivity pattern, and that binding to intracellular epitopes of BP180, in addition to NC16A, may be detectable at an early clinical stage. Our findings provide novel insights into the pathophysiology of bullous pemphigoid and show the potential of the utilized approach as a tool for a rapid diagnosis of bullous pemphigoid patients and their management.

Antibodies, Monoclonal↗
PubMed2001

Epitope mapping of factor VIII inhibitor antibodies of Chinese origin.

Epitopes recognized by factor VIII (FVIII) inhibitors of Chinese origin were analysed by immunoblotting with full-length recombinant FVIII (rFVIII), thrombin-activated FVIII (FVIIIa) and 16 FVIII fusion proteins synthesized by bacteria. Twenty-eight patients, 12 with haemophilia A and 16 with autoimmune diseases, were recruited. Antibodies from 22 patients showed reactivity with rFVIII, 20 with FVIIIa, and one reacted only with FVIII fusion proteins. Of these 22 cases, most were reactive with A2-a2 and A3-C1-C2 of FVIII(a). Of the nine cases that depicted binding to the fusion proteins, three were reactive with the A domains, three with only the B domain, and the other three with both the A and B (or C) domains. An epitope for a neutralizing antibody of a haemophilia A patient, designated TWN-112, was localized to residues 323-390, specified by FVIII fusion proteins. The same epitope also appeared on an FVIII-expression phage library screening. Immunoabsorption of antibodies from TWN-112 with the epitope reduced the neutralizing activity of the inhibitor by 33%. The incidence of a1 of FVIII is higher, and that of a3 is lower, than previously reported. Two novel epitopes, reported for the first time in this paper, were localized on the 8B2 (amino acid residues 1022-1204) and 8A2(V) (residues 673-740) fusion proteins. These two epitopes were able to reduce inhibitory antibody activity by 24% and 25% respectively. Changes of FVIII fragment specificity were also observed in one of six patients for whom multiple samples, collected at different times, were available. Our initial finding showed that the FVIII inhibitors in these Chinese patients shared epitopes with those of patients from very different genetic backgrounds, suggesting a common mechanism for the development of FVIII inhibitors.

Adolescent↗
PubMed2000

Comparative molecular modelling identifies a common putative IgE epitope on cysteine protease allergens of diverse sources.

BACKGROUND: Previous approaches for studying common allergenic epitopes have mainly focused on sequence comparisons, which unfortunately yield little or no information on the shape of the epitope which is the most important determinant of cross-reactivity. OBJECTIVES: The aim of this study was to investigate the structural basis for cross-reactivity between a previously identified immunodominant epitope of the house dust mite allergen Der p 1 (Leu147-Gln160) and the corresponding epitopes on other allergens that are either taxonomically closely related (i.e. cysteine proteases of other mite species) or representing evolutionary conserved structures (i.e. plant, human and parasite cysteine proteases). METHODS: We carried out comparative molecular modelling on a range of cysteine proteases, including those of other mite species (Der f 1 and Eur m 1), human (cathepsins B, K, L, S and O), plants (papain, chymopapain and actinidin) and parasites (cruzain, cathepsin L-like Leishmania protease, Entamoeba ACP1 protease and Schistosoma Q26534, Q11003 and cathepsin L proteases). RESULTS: Our study shows that all the cysteine proteases investigated here display an epitope corresponding to that previously identified on Der p 1, but with varying shapes and degree of accessibility. It appears that the core of the epitope on these homologous cysteine proteases consists of a centrally located conserved Tyr residue flanked on either sides by accessible amino acids. CONCLUSION: Therefore, these cysteine proteases seem to use similar accessible structures, which may form the basis for the rational design of generic epitope-directed treatment strategies for controlling allergic diseases.

Allergens↗
PubMed1998

Relationship between autoantibody epitopic recognition and immunoglobulin gene usage.

An immunodominant region recognized by serum autoantibodies has been defined on the autoantigen thyroid peroxidase (TPO) using recombinant human TPO-specific Fab or a panel of mouse MoAbs. We have now analysed the epitopic relationships between the four recombinant Fab that identify the A and B domains of the TPO immunodominant region and (i) the mouse TPO MoAb as well as (ii) nine new TPO-specific Fab isolated independently. Competition between mouse MoAbs and recombinant Fab for binding to 125I-TPO revealed three patterns. First, for MoAbs 15, 59, 64 and 18, TPO binding was virtually abolished (approximately 90%) by Fab which define the A domain of TPO, with less inhibition by B domain Fab. Second, for MoAbs 2, 9 and 47, the Fab competed much less for TPO binding, and, when detectable, inhibition was predominantly with B domain Fab (65-20%). Third, for MoAbs 53, 30, 1, 24 and 40, none of the Fab competed effectively for 125I-TPO binding. Thus, the epitopes for MoAbs 18, 59, 64 and 15 correspond to those of the A domain defined by the human Fab, and the epitopes for MoAbs 2, 9 and 47 correspond to those of the B domain. In the second part of the study, competition studies demonstrated that the epitopes of nine new Fab corresponded to those of the four Fab that define the immunodominant region. For four new Fab, TPO binding was inhibited to a greater extent by B- than by A-domain Fab (65-95% versus <50%). In contrast, for five new Fab the A-domain Fab were more effective inhibitors (approximately 90%) than the B-domain Fab. In addition, consistent with previous observations, all five new Fab with 02/012 kappa L chains, but none of the new Fab with non-O2/O121 chains, interacted with A-domain epitopes. In conclusion, we have established the epitopic relationships between recombinant human Fab and mouse MoAbs that define the TPO immunodominant region on TPO. Further, analysis of recombinant TPO Fab isolated from patients on three continents strengthens the paradigm of a relationship between autoantibody epitopic recognition and immunoglobulin gene usage.

Animals↗
PubMed2000

Cross-reactive epitopes and HLA-restriction elements in human T cell recognition of the Mycobacterium leprae 18-kD heat shock protein.

We have previously demonstrated that the Mycobacterium leprae 18-kD heat shock protein (HSP18) is represented among the antigenic targets of human T cell responses induced by M. leprae immunization and that the peptide 38-50 serves as an immunodominant epitope recognized by CD4+ T cell clones. By using peripheral blood mononuclear cells and T cell lines from the same donor group, we have in this study shown that the M. leprae HSP18 and peptide 38-50 were recognized by memory T cells 8 years after immunization with M. leprae. The finding that M. bovis BCG-induced T cell lines responded to M. leprae HSP18, but not to the peptide 38-50, suggested the existence of additional T cell epitopes of a cross-reactive nature. Consistent with this, testing of the T cell lines for proliferative responses to the complete HSP18 molecule, truncated HSP18 (amino acid (aa) residues 38-148) and overlapping synthetic peptides, made it possible to identify two cross-reactive epitope regions defined by aa residues 1-38 and 41-55. While peptide 38-50-reactive T cell clones showed limited cross-reactivity by responding to M. leprae, M. avium and M. scrofulaceum, the T cell lines specific to the epitopes 1-38 and 41-55 were broadly cross-reactive, as demonstrated by their response to M. leprae, M. tuberculosis complex, M. avium and other mycobacteria. MHC restriction analysis of the HSP18-responding T cell lines showed that the epitopes 1-38 and 38-50 were presented by one of the two HLA-DR molecules expressed from self HLA-DRB1 genes, whereas the epitope 41-55 was recognized in the presence of autologous as well as HLA-DR and HLA-DQ mismatched allogeneic antigen-presenting cells. The results obtained in this study made it possible to identify cross-reactive T cell epitopes of the M. leprae HSP18, and provide an explanation for T cell recognition of this antigen in individuals infected with species of the M. tuberculosis complex or environmental mycobacteria.

Amino Acid Sequence↗
PubMed2001

Identification of ricin A-chain HLA class II-restricted epitopes by human T-cell clones.

The identification of ricin toxin A-chain (RTA) epitopes and the molecular context in which they are recognized will allow strategies to be devised that prevent/suppress an anti-RTA immune response in patients treated with RTA-based immunotoxins. RTA-specific human T-cell lines and T-cell clones were produced by in vitro priming of PBMC. The T-cell clones used a limited set of Vbeta chains (Vbeta1, Vbeta2 and Vbeta8) to recognize RTA epitopes. The use of RTA deletion mutants demonstrated that T-cell lines and T-cell clones from three out of four donors responded to RTA epitopes within the domain D124-Q223, whereas one donor recognized the region I1-D124. The response to RTA peptides of T-cell lines and T-cell clones from two donors allowed the identification of immunogenic segments (D124-G140 and L161-T190) recognized in the context of different HLA-DRB1 alleles (HLA-DRB1*0801, and HLA-DRB1*11011 and B1*03011, respectively). The response to L161-T190 was investigated in greater detail. We found that the HLA-DRB1*03011 allele presents a minimal epitope represented by the sequence I175-Y183 of RTA, whereas the HLA-DRB1*11011 allele presents the minimal epitope M174-I184. RTA peptides and an I175A RTA point mutant allowed us to identify I175 as a crucial residue for the epitope(s) recognized by the two HLA-DRB1 alleles. Failure of T-cell clones to recognize ribosome inactivating proteins (RIPs) showing sequences similar but not identical to RTA further confirmed the role of I175 as a key residue for the epitope recognized in the context of HLA-DRB1*11011/03011 alleles.

Amino Acid Sequence↗
PubMed2003

Altered CD8+ T cell responses to selected Epstein-Barr virus immunodominant epitopes in patients with multiple sclerosis.

An increased frequency of antiviral CD8+ T cells is seen in chronic viral infections. During herpes virus infections the expanded CD8+ T cells are thought to control the reactivation of the latent infection. Because multiple sclerosis (MS), a presumed autoimmune disease of the central nervous system, has been associated with a late Epstein-Barr virus (EBV) infection, we wished to examine whether the CD8+ T cell response to EBV epitopes differed between MS patients and healthy controls. Here we report an increased frequency of CD8+ T cells responding to EBV epitopes from nuclear antigen 3 A (HLA-A2/CLG) and latent membrane protein 2 (HLA-B7/RPP) in MS patients. Noticeably, the altered CD8+ T cell response occurred to some but not all EBV epitopes and did not reach the high level seen during acute infection. The responses towards two immunodominant epitopes from human cytomegalovirus (HCMV) were similar in MS patients and normal controls. Together, our data demonstrate the presence of an increased frequency of CD8+ T cells reacting with two epitopes from EBV in patients with MS. The altered response to only two of the tested EBV epitopes would be consistent with the presence of cross-reactive epitopes.

Adult↗
PubMed2003

Thyroglobulin epitope recognition in a post iodine-supplemented Sri Lankan population.

OBJECTIVE: We previously reported a high prevalence of raised thyroglobulin autoantibodies (TgAb) in apparently healthy Sri Lankan schoolgirls following salt iodination. To characterize these antibodies further we determined the epitopes on thyroglobulin (Tg) with which they react and compared these with serum obtained from both healthy subjects and established autoimmune thyroid disease (AITD) patients from the UK. To extend our study to a wider population within Sri Lanka, we in addition determined the epitopes recognized by a group of AITD patients selected from a thyroid clinic in Sri Lanka, as well as apparently healthy female Sri Lankan tea workers of distinct ethnicity from the schoolgirls and AITD patients. DESIGN: Sri Lankan schoolgirls (n = 282) and adult female tea estate workers (n = 208) were examined for thyroid autoimmune markers. Sera with high TgAb (> 98 kIU/l) were selected from these two groups (n = 36 and 45, respectively) to study epitope-binding patterns. We also examined the sera from 16 AITD patients attending a thyroid clinic in Colombo, 16 patients with AITD from the thyroid clinic at the University Hospital of Wales and 16 sera from healthy control UK women with no evidence of thyroid disease. To determine the epitopes on Tg recognized by the subjects' TgAb, we employed a panel of Tg mouse monoclonal antibodies labelled with alkaline phosphatase in a competitive enzyme-linked immunosorbent assay reaction with the subjects' serum. RESULTS AND CONCLUSIONS: A majority of the Sri Lankan schoolgirls did not react with the immunodominant epitopes and did not differ significantly from healthy subjects from the UK in their Tg epitope recognition pattern. On the other hand, tea estate workers and Sri Lankan AITD patients recognized typical autoimmune thyroid disease epitopes and, in addition, recognized a separate cluster not previously associated with either the autoimmune state or the healthy state. The significance of this cluster requires further clarification.

Adolescent↗
PubMed1996

HLA-DR4-restricted T-cell epitopes from the mycobacterial 60,000 MW heat shock protein (hsp 60) do not map to the sequence homology regions with the human hsp 60.

The mycobacterial 60,000 MW heat shock protein (hsp 60) is a major antigen recognized by mycobacteria-reactive human CD4+ T cells with lymphokine profiles and effector functions consistent with protective immunity. In addition, the presence of a large number of T-cell epitopes presented by several HLA class II molecules makes this antigen relevant to subunit vaccine design. However, the results from animal models as well as human studies suggest that the mycobacterial hsp 60 may induce T-cell-mediated autoimmune conditions. In humans, the expression of HLA-DR4 represents a risk factor for some autoimmune diseases. These observations suggest that the epitopes from the mycobacterial hsp 60 presented to T cells in the context of HLA-DR4 could be relevant to autoimmunity. This is the first report on identification of HLA-DR4-restricted T-cell epitopes from the mycobacterial antigen hsp 60. In total, five epitopes recognized in the context of HLA-DR4 by the M. leprae hsp 60-reactive CD4+ T-cell clones from a subject immunized with M. leprae were defined by synthetic peptides. Two of the epitopes were M. leprae-specific (aa 343-355, aa 522-534), whereas three epitopes were common to M. leprae and M. tuberculosis (aa 331-345, aa 441-455, aa 501-515). However, all of these epitopes belong to the regions that are highly divergent between the mycobacterial hsp 60 and the homologous human hsp 60 sequence, suggesting that the T cells recognizing the mycobacterial hsp 60 in the context of HLA-DR4 may not necessarily induce autoreactivity.

Amino Acid Sequence↗
PubMed2001

Differing processing requirements of four recombinant antigens containing a single defined T-cell epitope for presentation by major histocompatibility complex class II.

A set of predictive rules governing the likelihood of generating a particular peptide-major histocompatibility complex (MHC) class II complex from an intact antigen has not been fully elucidated. We investigated the influence of positional and structural constraints in the region of the epitope by designing a set of recombinant antigens that each contained the well-characterized T-cell epitope moth cytochrome c (MCC) (88-103), which is specifically recognized by the monoclonal antibody (mAb) D4 when complexed with H-2Ek. Our model antigens contained MCC(88-103) either peripherally, at or towards the C-terminus, or internally. Their abilities to bind directly to soluble H-2Ek, and the extent of D4 epitope formation from them by antigen processing-competent and -incompetent cell lines, were determined. Here we report that three of these four antigens yielded MCC(88-103)/H-2Ek complexes independently of the conventional MHC class II antigen-processing and presentation pathway, and in each case the epitope was carried peripherally; two bound directly as intact proteins, probably as a result of spatial separation of the epitope from the major globular domain, and one was processed to peptide by a cell-surface protease. One protein, which carried the epitope inserted into an internal loop, acted as a conventional processing-dependent MCC(88-103) delivery vehicle. Thus, this epitope has different presentation requirements depending on its context. These antigens constitute a panel whose framework could be modified to further define predictive rules for antigen processing for presentation through the different MHC class II complex-generating pathways.

Animals↗
PubMed2002

Limitations of HLA-transgenic mice in presentation of HLA-restricted cytotoxic T-cell epitopes from endogenously processed human papillomavirus type 16 E7 protein.

We investigated the use of mice transgenic for human leucocyte antigen (HLA) A*0201 antigen-binding domains to test vaccines composed of defined HLA A*0201-restricted cytotoxic T-lymphocyte (CTL) epitopes of human papillomavirus (HPV) type 16 E7 oncoprotein. HPV is detected in >90% of cervical carcinomas. HPV16 E7 oncoprotein transforms cells of the uterine cervix and functions as a tumour-associated antigen to which immunotherapeutic strategies may be directed. We report that although the HLA A*0201 E7 epitope peptides function both to prime for E7 CTL responses, and to sensitize target cells for E7-directed CTL killing in situations where antigen processing is not required, the epitopes are not processed out of either endogenously expressed or immunization-introduced E7, by the mouse antigen-processing and presentation machinery. Thus (1) CTL induced by HLA A*0201 peptide immunization killed E7 peptide-pulsed target cells, but did not kill target cells expressing whole E7; (2) immunization with whole E7 protein did not elicit CTL directed to HLA A*0201-restricted E7 CTL epitopes; (3) HLA A*0201-restricted CTL epitopes expressed in the context of a DNA polytope vaccine did not activate E7-specific T cells either in 'conventional' HLA A*0201 transgenic (A2.1Kb) mice, or in HHD transgenic mice in which expression of endogenous H-2 class 1 is precluded; and (4) HLA A*0201 E7 peptide epitope immunization was incapable of preventing the growth of an HLA A*0201- and E7-expressing tumour. There are generic implications for the universal applicability of HLA-class 1 transgenic mice for studies of human CTL epitope presentation in murine models of human infectious disease where recognition of endogenously processed antigen is necessary. There are also specific implications for the use of HLA A2 transgenic mice for the development of E7-based therapeutic vaccines for cervical cancer.

Animals↗
PubMed2003

Paucity of functional CTL epitopes in the E7 oncoprotein of cervical cancer associated human papillomavirus type 16.

Many specific antiviral and antitumour immune responses have been attributed to the protective effects of antigen-specific CD8+ cytotoxic T lymphocytes (CTL). Recognition of virus infected or tumour cells by CTL requires presentation of at least one peptide epitope from a virus or tumour-specific antigen by the relevant MHC Class I molecule. Viral genes with mutations which remove CTL epitopes may thus be favoured for survival. Human cervical cancers are caused by papillomavirus infection, and these cancers consistently express the E7 protein of the oncogenic papillomavirus. We therefore investigated the MHC Class I restricted T cell epitopes of the human papillomavirus type 16 E7 oncoprotein using mice of five different genetic backgrounds, and an IFN-gamma ELISPOT assay, to determine the frequency with which MHC Class I epitopes might be expected in this small oncoprotein (98 amino acids). No MHC Class I restricted responses were detected in E7 immunized BALB/c (H-2d), CBA/CaH (H-2 k), FVB/N (H-2q) or A2KbH2b human HLA2.1 transgenic mice. In C57BL/6 J (H-2b) mice, a previously identified single antigenic epitope was detected. Therefore, we conclude that there is a paucity of MHC Class I restricted T cell epitopes in HPV16 E7 protein because of its small size. This might be advantageous to the virus. Furthermore here we present a quick and easy method to exhaustively determine CD8 T cell epitopes in proteins using a unique set of overlapping 8, 9 and 10 mer synthetic peptides.

Animals↗
PubMed2002

Wild-type and 'a' epitope variants in chronic hepatitis B virus carriers positive for hepatitis B surface antigen and antibody.

AIMS: This study aims to examine the genomic variants of the 'a' epitope in chronic hepatitis B virus (HBV) carriers positive for both hepatitis B surface antigen (HBsAg) and antibody to HBsAg (anti-HBs). METHODS: Eighteen HBV carriers were studied. Hepatitis B virus (HBV) DNA was extracted and the 'a' epitope region was amplified and sequenced. RESULTS: Eighteen Chinese asymptomatic HBV carriers were studied. There were 13 patients who were positive for both HBsAg and anti-HBs. Of these, one patient had only wild-type HBV, three had a viral mixture, and five had only 'a' epitope variant HBV. Of the three patients with a viral mixture, all had variants in the less conserved region (123-137). Of the five patients with pure HBsAg mutants, three had variants in the less conserved region while two had variants in the highly conserved region. In this study with a limited number of patients, the serum alanine aminotransferase (ALT) levels were higher in patients with wild-type HBV, compared with those with either 'a' epitope variants or a viral mixture consisting of wild type and variants. CONCLUSION: Eight of the nine (89%) patients positive for both HBsAg and anti-HBs harbored an 'a' epitope variant. The lower ALT levels seen in patients who had either pure 'a' epitope variant or a mixture of wild type and mutants suggest that a closer monitoring of these 'a' epitope variants should be required, as patients carrying these infectious viral strains may remain asymptomatic.

Adult↗
PubMed1997

The neurofilament antibody RT97 recognises a developmentally regulated phosphorylation epitope on microtubule-associated protein 1B.

Microtubules are important for the growth and maintenance of stable neuronal processes and their organisation is controlled partly by microtubule-associated proteins (MAPs). MAP 1B is the first MAP to be expressed in neurons and plays an important role in neurite outgrowth. MAP 1B is phosphorylated at multiple sites and it is believed that the function of the protein is regulated by its phosphorylation state. We have shown that the monoclonal antibody (mAb) RT97, which recognises phosphorylated epitopes on neurofilament proteins, fetal tau, and on Alzheimer's paired helical filament-tau, also recognises a developmentally regulated phosphorylation epitope on MAP 1B. In the rat cerebellum, Western blot analysis shows that mAb RT97 recognises the upper band of the MAP 1B doublet and that the amount of this epitope peaks very early postnatally and decreases with increasing age so that it is absent in the adult, despite the continued expression of MAP 1B in the adult. We confirmed that mAb RT97 binds to MAP 1B by showing that it recognises MAP 1B immunoprecipitated from postnatal rat cerebellum using polyclonal antibodies to recombinant MAP 1B proteins. We established that the RT97 epitope on MAP 1B is phosphorylated by showing that antibody binding was abolished by alkaline phosphatase treatment of immunoblots. Epitope mapping experiments suggest that the mAb RT97 site on MAP 1B is near the N-terminus of the molecule. Despite our immunoblotting data, immunostaining of sections of postnatal rat cerebellum with mAb RT97 shows a staining pattern typical of neurofilaments with no apparent staining of MAP 1B. For instance, basket cell axons and axons in the granule cell layer and white matter stained, whereas parallel fibres did not. These results suggest that the MAP 1B epitope is masked or lost under the immunocytochemical conditions in which the cerebellar sections are prepared. The upper band of the MAP 1B doublet is believed to be predominantly phosphorylated by proline-directed protein kinases (PDPKs). PDPKs are also good candidates for phosphorylating neurofilament proteins and tau and therefore we postulate that the sites recognised by RT97 on these neuronal cytoskeletal proteins may be phosphorylated by similar kinases. Important goals are to determine the precise location of the RT97 epitope on MAP 1B and the kinase responsible.

Animals↗
PubMed1998

Epitope spreading: lessons from autoimmune skin diseases.

Autoimmune diseases are initiated when patients develop aberrant T and/or B cell responses against self proteins. These responses presumably are directed to single immunogenic epitopes on these proteins. Recent data in animal models of autoimmune diseases suggest that the targets of immune responses in autoimmunity do not remain fixed, but can be extended to include other epitopes on the same protein or other proteins in the same tissue, a phenomenon termed "epitope spreading." The "epitope spreading" phenomenon also applies to situations in which tissue damage from a primary inflammatory process causes the release and exposure of a previously "sequestered" antigen, leading to a secondary autoimmune response against the newly released antigen. In experimental autoimmune animal diseases, "epitope spreading" seems to have significant physiologic importance in determining the course and duration of disease. In this paper, we review the current concepts in animal models of autoimmune diseases in order to define the "epitope spreading" phenomenon, and we then propose how this phenomenon might play a significant role in the development and the course of autoimmune skin diseases. Hopefully, an understanding of "epitope spreading" will help the dermatology community to better understand the pathogenesis of autoimmune skin diseases and to rationally fashion disease-specific immune therapy in the future.

Animals↗
PubMed2006

Neutralization epitope responsible for the hepatitis B virus subtype-specific protection in chimpanzees.

Neutralizing monoclonal antibody (BX-182) directed against the d determinant of hepatitis B virus (HBV) surface antigen protected chimpanzees from infection by HBV subtype adw but not by subtype ayw, as demonstrated by intravenously inoculating a mixture of the antibody with the respective subtype of the virus. To elucidate the mechanism underlying the subtype-specific protection, a combinatorial approach of screening random peptide phage libraries, bioinformatics, and structure analysis was used in this study to identify the neutralization epitope responsible for the observed protection. The epitope was mapped at the N terminus of the pre-S1 region of the hepatitis B surface antigen between residues 17 and 21, of which the residues Val-18/Pro-19 were critical for antibody binding. Alignment of amino acid sequences derived from diverse genetic variants of HBV revealed that the epitope was present in ad subtypes and in their corresponding genotypes A, B, C, F, and H. By contrast, this epitope was not found in a majority of ay subtypes or in genotypes D, E, and G, where the antigenic residues Val-18/Pro-19 within the epitope were replaced by Thr/Ser, Thr/Thr, or Ala/Ser, respectively, resulting in a drastic conformational change of the epitope. These data indicate that, by binding discriminately to the subtype "d" epitope in the pre-S1 region, neutralizing antibody BX-182 protects chimpanzees from HBV infection in a subtype-specific manner, suggesting a potential escape mechanism for HBV genetic variants.

Amino Acid Sequence↗