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PubMed1991

Epitope mapping of the Syrian hamster prion protein utilizing chimeric and mutant genes in a vaccinia virus expression system.

The cellular prion protein (PrPc) is a host-encoded sialoglycoprotein bound to the external surface of the cell membrane by a glycosyl phosphatidylinositol anchor. A posttranslationally modified PrP isoform (PrPSc) is a component of the infectious particle causing scrapie and the other prion diseases. mAb have been raised against the protease-resistant core of Syrian hamster (SHa) PrPSc designated PrP 27-30. To map the epitopes within PrP reacting to these antibodies, we have expressed wild-type, chimeric mouse (Mo)/SHa and mutant MoPrP genes using recombinant vaccinia virus systems. The fidelity of the expression of recombinant PrPC was examined using vaccinia viruses expressing SHa-PrPC. It is full length, possesses Asn-linked carbohydrates and is attached to the external surface of the cell membrane by a glycosyl phosphatidylinositol anchor that is sensitive to cleavage by phosphatidylinositol-specific phospholipase C. We have tested 18 mAb for their ability to bind to chimeric prion proteins on immunoblots. Three distinct epitopes were identified that mapped to amino acid differences between SHa and MoPrP sequences. The first epitope, recognized by three of the antibodies tested, was defined by methionines at amino acids 108 and 111 in the mouse protein. The second epitope was dependent upon the presence of asparagines at positions 154 and 174 in MoPrP and was recognized by four of the antibodies tested. The third epitope mapped to a single amino acid substitution at residue 138 in MoPrP. mAb raised against SHaPrP 27-30 specific for this epitope are able to bind MoPrPC which has a single amino acid change (Ile to Met) at position 138. Eleven of the 18 antibodies tested mapped to this immunodominant epitope. It is located within a postulated amphipathic helix, a structure associated with immunodominant Ag. Inasmuch as PrPC, in its native form on the cell surface, is detected by the mAb 13A5 (a prototypic antibody of the immunodominant third epitope class), it is likely that this epitope is accessible in the native conformation of this protein.

Animals↗
PubMed1986

Epitope expression on primate lymphocyte surface antigens.

The cross-reactivity of peripheral blood mononuclear cells from 28 nonhuman primates was investigated with ten kinds of Leu series of monoclonal antibodies specific to human T-, natural killer/killer-, and B-cells. The chimpanzees possessed all ten epitopes examined but the orangutan lacked Leu4 and Leu7 epitopes and the gibbons lacked Leu4, Leu7, and Leu12 epitopes. In addition to the above epitopes, the Old World monkeys lacked Leu1 and Leu10 epitopes. The Leu3a/Leu2a cell ratios varied from 0 to 1.56 among the 12 macaque species and this enabled classification of these species into three groups. In the New World monkeys, Leu2a epitope was absent, whereas Leu11a epitope was detected in several species and Leu3a epitope was found only in the owl monkeys. The prosimians expressed only HLA-DR epitope.

Animals↗
PubMed1987

Monoclonal antibody characterization of the 195-kilodalton major surface glycoprotein of Plasmodium falciparum malaria schizonts and merozoites: identification of additional processed products and a serotype-restricted repetitive epitope.

The gp195 from Camp strain parasites was characterized with eight monoclonal antibodies (MAb) that recognize different epitopes on gp195 and three of its merozoite-associated processed products. Four MAb (3H7, 3B10, 7F1, and 4G12) reacted with different epitopes on the 45-kDa glycosylated product (gp45), shown by differences in their reactivities with soluble and immunoblotted gp45. One MAb (7H10) reacted with a conformational epitope probably formed as a result of the interaction of gp45 with a nonglycosylated 45-kDa product (p45). Three other MAb (3D3, 7B11, and 7B2) reacted with different epitopes on a nonglycosylated 83-kDa product (p83), shown by differences in their reactivities against various parasite isolates in immunofluorescent antibody assays. Immunoprecipitation of antigens that were pulse-labeled with [3H]isoleucine and chased with cold isoleucine showed that p45 and gp45 were processed products of gp195 and p83 was sequentially processed into smaller fragments of 73 and 67 kDa (p73 and p67). Immunoblots showed that the 7B11 and 7B2 epitopes were present on p83, p73, and p67, but that the 3D3 epitope was present only on p83 and p73. A two-site immunoassay showed the 3D3 epitope to be repetitive. The 3D3 and 7B11 epitopes were serotype restricted (present in seven and 24 of 33 isolates, respectively), but the other five epitopes were common to all isolates tested. The gp195 and its processed products have Mr that are consistent with the Mr of a number of antigens shown previously to be associated with the immune complexes that are formed when merozoites are agglutinated by antibodies contained in some growth inhibitory immune sera.

Animals↗
PubMed1988

Generation and epitope analysis of thyroid stimulating hormone-specific monoclonal antibodies for enzyme immunoassays.

By using an improved hybridoma technique with a semisolid medium of methylcellulose for initial cloning, numerous high affinity monoclonal antibodies against human thyroid stimulating hormone (TSH) were generated. These antibodies were characterized with respect to their subunit and epitope specificity. Epitope analysis of antibodies specific to the beta-subunit of TSH was performed by a sandwich pairing procedure. Based on the results of this analysis, it was concluded that there are four distinct TSH-specific epitopes on the beta-subunit of TSH; these are designated a, b, c, and ab. The five antibodies binding to epitopes a, b, and c are not mutually exclusive. However, the antibody binding to epitope ab prevents further binding of other antibodies to epitope a or b, but not to epitope c. This epitope analysis enabled us to combine three high affinity monoclonal antibodies, each of which reacts with epitopes a, b, and c, respectively, in a typical sandwich enzyme immunoassay. One was immobilized on polystyrene beads and the other two were conjugated with horseradish peroxidase and served as the second antibodies. This enzyme immunoassay can be performed within 90 min and with a minimum sensitivity of 0.2-0.3 microIU/ml.

Antibodies, Monoclonal↗
PubMed1988

Independent regulation of B cell responses to surface and subsurface epitopes of African trypanosome variable surface glycoproteins.

Regulation of B cell responses to the trypanosome surface Ag was examined in H-2k compatible "responder" B10.BR and "nonresponder" C3H mice after infection with two variant clones of Trypanosoma brucei rhodesiense. Development of a selective RIA for independent detection of antibody binding to surface (exposed) and subsurface (buried) epitopes of the trypanosome variable surface glycoprotein (VSG) molecule permitted sensitive quantitation and kinetic characterization of immune responses to these epitopes. The infected B10.BR mice responded to both exposed and buried VSG epitopes of clone LouTat 1 trypanosomes, whereas a B cell response by C3H mice to exposed VSG epitopes was not detected by RIA analyses at any time. However, VSG-specific IgM and IgG responses were produced to buried VSG epitopes, demonstrating that LouTat 1 induced immunoregulation was specific only for the B cell responses to exposed VSG epitopes. Subsequently, comparisons of B10.BR and C3H B cell responses to a heterologous variant, LouTat 1.5, were made. The results revealed that both infected mouse strains produced VSG 1.5-specific antibody to exposed and buried epitopes with different kinetics and maximal sera concentrations, showing, therefore, that these responses are not coordinately regulated. In addition, it was clear that the observed immunosuppression to exposed LouTat 1 VSG epitopes in C3H mice could be regulated by the parasite since functional C3H B cell responses were mounted against exposed VSG epitopes of a closely related variant (LouTat 1.5) after infection.

Animals↗
PubMed1988

Antitubulin antibodies. II. Natural autoantibodies and induced antibodies recognize different epitopes on the tubulin molecule.

Natural and induced antitubulin antibodies were compared for their epitope recognition on alpha- and beta-tubulin subunits by immunoenzymatic assays and Western blot techniques on partially digested tubulin molecules. Our results indicated that natural autoantibodies recognized different epitopes from those recognized by induced antibodies, because: 1) all polyspecific natural autoantibodies tested so far recognized the same or very overlapping epitopes in the central part of both alpha- and beta-subunits (between positions 100 and 300 on the tubulin amino acid sequence) and that this epitope differed from the various epitopes recognized by induced antitubulin antibodies on the amino-terminal or carboxy-terminal parts of the tubulin subunits; 2) one human myeloma protein (monoclonal (m)IgA, kappa) with a monospecific antitubulin activity bound to an epitope around position 310 on both alpha- and beta-subunits and a second human mIg (mIgM, kappa) with a monospecific anti-beta activity bound to an epitope on the carboxy-terminal part of the subunit around amino acid position 350. Both epitopes differed from epitopes recognized by induced antitubulin antibodies. These results thus confirmed our previous findings indicating that natural and induced antitubulin antibodies do not share cross-reactive idiotopes.

Animals↗
PubMed1994

Direct sequence identification and kinetic analysis of an MHC class I-restricted Listeria monocytogenes CTL epitope.

Murine infection with the intracellular bacterium Listeria monocytogenes elicits MHC class I-restricted CTL with specificity for multiple bacterial peptides. The variety and relative abundance of self-peptides bound by MHC molecules make identification of pathogen-derived peptides difficult. In this report, the sequence of a pathogen-derived CTL epitope is determined by direct analysis of peptides extracted from MHC class I molecules. The epitope, p60 217-225, is presented to L. monocytogenes-specific CTL by the H-2Kd MHC class I molecule and is derived from p60, a secreted invasion-associated protein. Quantitation of p60 217-225 in infected cells shows that this epitope is detectable within 2 h of infection and, after a 9-h infection, there are over 3000 epitopes per infected cell. This contrasts with listeriolysin 91-99, the other major L. monocytogenes epitope, which is present in quantities below 200 epitopes per cell until 5 h of infection and reaches 800 epitopes per cell 9 h after infection. This report shows that identifying new T lymphocyte epitopes by direct sequence analysis of peptides isolated from MHC molecules is feasible. Furthermore, kinetic and quantitative analysis of T cell epitopes in infected cells is a useful approach to investigate the multispecific CTL response to complex intracellular pathogens.

Amino Acid Sequence↗
PubMed1993

Structural dissection of the multidomain kininogens. Fine mapping of the target epitopes of antibodies interfering with their functional properties.

Kininogens, the large precursor molecules of the vasoactive kinin peptides, are prototypic multidomain proteins serving numerous functions. To investigate their structure-function relationships, we have raised a panel of monoclonal antibodies against human H-kininogen and L-kininogen and fragments thereof and characterized them with respect to their target epitopes. Of 35 antibodies, 12 were directed to the amino-terminal domains (D1 to D3) of cystatin-like structure, 3 recognized domain D4 bearing the kinin segment, 17 bound to the carboxyl-terminal domains of H-kininogen (D5H and D6H), and 3 bound to the carboxyl-terminal domain D5L of L-kininogen. At least 14 distinct epitopes spread over the kininogen molecules were identified: 9 epitopes located on L-kininogen and 13 epitopes harbored by H-kininogen. Of these, 8 are shared by the two types of kininogens. Fine mapping of the epitopes by proteolytic fragments, recombinant proteins, and anti-idiotypic antibodies demonstrated that most but not all of the antibodies recognize liner epitopes. Synthesis of 28 peptides covering more than one-third of the entire kininogen sequences allowed us to narrow down seven major epitopes to 7-31 residues. Functional analyses identified 14 antibodies interfering with specific biological roles of the kininogens, i.e. cysteine proteinase inhibition, platelet attachment, cofactor binding, contact activation, and kinin delivery. Cross-reactivity studies indicated that three of the epitopes are present throughout the mammalian kininogens and further identified a unique epitope characteristic for the H/L-type of kininogens not present in their T-type. The panel of mapped antibodies provides powerful tools for the characterization of relevant interaction sites exposed by the pleiotropic kininogens and for the development of molecular surrogates mimicking these functional loci.

Amino Acid Sequence↗
PubMed1996

Location of a protease-hypersensitive region in the multidrug resistance protein (MRP) by mapping of the epitope of MRP-specific monoclonal antibody QCRL-1.

Multidrug resistance protein (MRP) is a Mr 190,000 integral membrane phosphoglycoprotein which has been shown by transfection studies to confer multidrug resistance. We have previously raised and characterized a panel of MRP-specific monoclonal antibodies (MAbs) which detect distinct epitopes in the MRP molecule (D. R. Hipfner et A, Cancer Res., 54. 5788-5792, 1994), and, in the present study, we have identified the epitope of one of these, MAb QCRL-1. Immunoblot analysis of MRP fragments generated by digestion with formic acid or trypsin suggested that the MAb QCRL-1 epitope was located in the region connecting the two halves of MRP. Subsequent analyses of a series of truncated bacterial glutathione S-transferase fusion proteins containing segments of human MRP further localized the MAb QCRL-1 epitope to a region encompassing amino acids 903-956. Similar experiments with an analogous segment of murine MRP demonstrated that MAb QCRL-1 was highly specific for the human protein. The reactivity of MAb QCRL-1 with a series of overlapping hexapeptides and heptapeptides within this region identified the human MRP-specific heptapeptide SSYSGDI (corresponding to amino acids 918-924) as the epitope, and this peptide was shown to specifically inhibit MAb QCRL-1 binding to MRP. The results of these studies confirm that this epitope has a cytoplasmic location consistent with the topology of MRP predicted from hydrophobicity analyses. These experiments also revealed the presence of a number of protease-sensitive sites on either side of the MAb QCRL-1 epitope in the cytoplasmic domain connecting the two halves of MRP. Future epitope-mapping studies with other MRP-specific MAbs win provide additional insights into the topology of MRP, and may help to identify functionally important regions of this protein. Moreover, definition of the epitope recognized by MAb QCRL-1 as well as the other MAbs will facilitate the use of these reagents for immunohistological studies of MRP expression in drug-resistant tumors.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1997

Efficient priming of CD8+ memory T cells specific for a subdominant epitope following Sendai virus infection.

The relationship between the primary effector CTL response to viral infection and the subsequent pool of memory CTL precursors (CTLp) is poorly understood. Here, we have analyzed the induction of both effector CTL and memory CTLp to dominant and subdominant epitopes following Sendai virus infection of C57BL/6 mice. A single peptide derived from the Sendai virus nucleoprotein (NP(324-332)) binds to both H-2 Kb and Db MHC class I molecules, generating both immunodominant (NP(324-332)/Kb) and subdominant (NP(324-332)/Db) epitopes. Following intranasal Sendai virus infection, NP(324-332)/Kb-specific CTL dominated the primary effector CTL response in the lung and were present at high frequency in the memory CTLp pool. In contrast, NP(324-332)/Db-specific CTL were not a detectable component of the effector response to primary Sendai virus infection. However, memory CTLp specific for this subdominant epitope were induced at frequencies approaching those of CTLp specific for the immunodominant epitope. These data indicate that memory CTLp specific for subdominant epitopes can be primed by Sendai virus infection in the absence of a detectable effector response. To determine whether CTLp memory to subdominant epitopes is functional in the context of Sendai virus infection, memory CTLp specific for a subdominant epitope were selectively primed by vaccination. These cells dominated the subsequent effector CTL response to Sendai virus infection, demonstrating that memory CTLp primed against subdominant epitopes can participate in an immune response and effectively compete with T cells specific for immunodominant epitopes. These data have implications for the development of vaccines designed to emphasize cellular immunity.

Animals↗
PubMed1997

Mutagenesis of an immunodominant T cell epitope can affect recognition of different T and B determinants within the same antigen.

The effects of mutagenesis of residues of a major T cell epitope were investigated in order to expand knowledge from synthetic peptides to the naturally processed antigen. The impact of substitutions within the core of the immunodominant p61-80/PT19 mycobacterial epitope was ascertained in respect of this epitope per se, or of a C-terminal (140-159) overlapping T/B epitope and of a conformational B epitope. The core substitution A71L impaired T immunogenicity of the target epitope within the protein, but not in the peptide, whereas the N73A substitution impaired the responses in both instances. Notably, each of these single amino acid mutations abrogated the T but not the B immunogenicity of the C-terminal epitope. Furthermore, mutation of five core residues (71-76) also ablated expression of a monoclonal antibody defined conformational B epitope. In conclusion, immunological analysis of mutated proteins revealed functional associations between topographically distinct antigenic determinants which may account for the previously observed differences in the specificity of immune responses between immunised and infected hosts.

Animals↗
PubMed1996

Mucosal tolerance and suppression of collagen-induced arthritis (CIA) induced by nasal inhalation of synthetic peptide 184-198 of bovine type II collagen (CII) expressing a dominant T cell epitope.

The purpose of the study was to map the dominant T cell epitope of the CB11 sequence of CII in RTlu haplotype rats and to determine if, when used as a synthetic peptide, it would induce tolerance to protect against CIA. A dominant epitope corresponding to residues 184-198 included in the sequence of the CB11 fragment of bovine CII was identified in proliferation assay using peptides in an epitope scanning system using synthetic peptides of 15 amino acids, overlapping by 12 amino acids. This epitope is bovine-specific, but cross-reacts with the corresponding rat peptide. Minor epitopes in the bovine CB11 sequence was also autoantigenic. Use of independently synthesized and purified 184-198 peptide confirmed its dominance in the T cell responses of arthritic rats. The peptide itself was not arthritogenic. Cells from lymph nodes draining arthritic feet were particularly responsive to the dominant peptide sequence, and showed evidence of epitope spreading to include reactions to at least four subdominant epitopes. Mucosal tolerance was successfully induced by instilling CII into the nose of rats before induction of CIA: this was found to delay the onset of disease, reduce mean disease severity, shift the anti-CII antibody response to favour antibodies of the IgG1, rather than the IgG2b isiotype, and to reduce T cell reactivity to both CII and to the 184-198 peptide. The dominant 184-198 peptide itself had the same tolerogenic effects when given nasally to rats daily, on the 4 days immediately preceding the induction of CIA. Two forms of CIA with acute and delayed disease onset were each modified by pre-treatment with the peptide. This study demonstrates that mucosal tolerance to CII can be induced by delivering it nasally in a way similar to that achieved previously by oral delivery, and that the use of an immunodominant epitope contained in a synthetic peptide will also suppress the immunologic and arthritic responses to collagen.

Administration, Inhalation↗
PubMed2003

Identification of B- and T-cell epitopes of BB, a carrier protein derived from the G protein of Streptococcus strain G148.

Most conventional vaccines consist of killed organisms or purified antigenic proteins. Such molecules are generally poorly immunogenic and need to be coupled to carrier proteins. We have identified a new carrier molecule, BB, derived from the G protein of Streptococcus strain G148. We show that BB is able to induce strong antibody responses when conjugated to peptides or polysaccharides. In order to localize T and B cell epitopes in BB and match them with the albumin-binding region of the molecule, we immunized mice with BB, performed B and T pepscan analyses, and compared the results with pepscan done with sera and cells from humans. Our results indicate that BB has two distinct T helper epitopes, seven linear B-cell epitopes, and one conformational B-cell epitope in BALB/c mice. Four linear B-cell epitopes were identified from human sera, three of which overlapped mouse B-cell epitopes. Finally, three human T-cell epitopes were detected on the BB protein. One of these T-cell epitopes is common to BALB/c mice and humans and was localized in the region that contains the albumin-binding site. These data are of interest for the optimization of new carrier molecules derived from BB.

Amino Acid Sequence↗
PubMed1998

Generation of the vesicular stomatitis virus nucleoprotein cytotoxic T lymphocyte epitope requires proteasome-dependent and -independent proteolytic activities.

The proteasome is involved in the generation of most of the MHC class I antigenic epitopes. However, it is not known if the proteasome generates the exact cytotoxic T lymphocyte (CTL) epitope or only epitope precursors which require further modification by additional proteases. Digestion of the extended vesicular stomatitis virus nucleoprotein epitope 52-59 (RGYVYQGL) by the 20S proteasome in vitro shows that the proteasome is capable of generating the correct C terminus but not the exact N terminus of the CTL epitope. This finding suggests that proteolytic activity in addition to the proteasome is required for generation of the CTL epitope. By using the proteasome inhibitor lactacystin we were able to confirm this finding in vivo. Lactacystin prevented the processing of N- and C-terminally extended epitopes, whereas the processing of only N-terminally extended epitopes was unaffected. Thus, the proteasome is necessary and sufficient for the generation of the exact C terminus of this CTL epitope, whereas the exact N terminus seems to be generated by a different protease.

Acetylcysteine↗
PubMed1991

Oncofetal mucin M1 epitope family: characterization and expression during colonic carcinogenesis.

The gastric mucin M1 antigens, markers associated with colonic carcinogenesis, have been characterized by new antimucin monoclonal antibodies (MAbs). These MAbs, obtained against mucins isolated from a human ovarian mucinous cyst (MAbs 19M1, 21M1 and 45M1) and from a pancreatic adenocarcinoma (MAb 96RA), were compared with 5 other anti-M1 mucin MAbs described previously, which characterized the a, b, c, d and e mucin M1 epitopes. Using immunoperoxidase, these new MAbs exclusively stained the surface gastric epithelium of normal human gastro-intestinal tract and reacted with fetal, precancerous and cancerous colonic mucosa, but not with normal colon. Immunoradiofixation studies showed that these new MAbs are directed against 3 epitopes (f, g and h) which are different from the a, b, c, d and e mucin M1 epitopes, though present on the same a immunoreactive high-molecular-weight components (greater than 1,000 kDa) with a density of 1.4 by CsCl-density-gradient ultracentrifugation. M1 antigenicity is characterized by a family of 8 different M1 epitopes which were destroyed with beta-mercaptoethanol (except for the f epitope), sensitive to a 5 hr trypsin treatment and resistant to 5 mM periodate (except for the h epitope). Some epitopes (b, c and d) showed increasing immunoreactivity after 20 mM periodate treatment, suggesting cryptic location. In rat-colon adenocarcinomas, M1 mucin epitopes were masked but could be decrypted using high periodate treatment, similar to normal rat gastric mucosa, thus suggesting the absence of drastic changes in the saccharide coat of the peptide mucin portion bearing M1 epitopes. Cryptic location, periodate resistance, sensitivity to protease and conformational behavior strongly suggest that the peptidic core of gastric (or fetal colonic) mucin plays a role in M1 immunoreactivity. Indeed, the resurgence of M1 antigens during colonic carcinogenesis is due to re-expression of the peptide core of gastric (or fetal colonic) mucins.

Animals↗
PubMed1982

Immunochemical heterogeneity of human plasma apolipoprotein B. II. Expression of apolipoprotein B epitopes on native lipoproteins.

Eleven hybridoma antibodies specific for apoprotein B were used to examine the expression of apoprotein B epitopes on native plasma lipoproteins using fluid phase radioimmunoassays. Heterogeneity of apoprotein B in low density lipoprotein (LDL) of density 1.019-1.063 g/ml was indicated by maximum binding of radioiodinated LDL in the presence of excess antibody that ranged from 45 to 100%. Affinity constants for LDL ranged from 0.29-3.0 X 10(9) M-1. Each of the 11 antibodies recognized apoprotein B epitopes that were expressed by very low, intermediate, and low density lipoproteins, VLDL, IDL, and LDL, respectively, since at high concentrations, each could fully displace the binding of radioiodinated LDL. In contrast, these same apoprotein B epitopes were not present on high density lipoproteins. Logit transformation analysis of competitive inhibition titrations demonstrated at least three patterns of epitope expression. The first pattern, identified by five of the antibodies, was characterized by indistinguishable expression of each of the apoprotein B epitopes on VLDL, IDL, and LDL. The second pattern, identified by three antibodies, was characterized by identical expression of the apoprotein B epitopes on VLDL and IDL, but of differing affinities than the related epitope on LDL. Three antibodies identified a third pattern of epitope expression which was was characterized by identical expression on IDL and LDL, but with differing affinities for the antibodies than the same epitopes on VLDL. These observations suggest that the organization of apoprotein B in VLDL, IDL, and LDL is similar, but not identical.

Animals↗
PubMed2006

Prediction of continuous B-cell epitopes in an antigen using recurrent neural network.

B-cell epitopes play a vital role in the development of peptide vaccines, in diagnosis of diseases, and also for allergy research. Experimental methods used for characterizing epitopes are time consuming and demand large resources. The availability of epitope prediction method(s) can rapidly aid experimenters in simplifying this problem. The standard feed-forward (FNN) and recurrent neural network (RNN) have been used in this study for predicting B-cell epitopes in an antigenic sequence. The networks have been trained and tested on a clean data set, which consists of 700 non-redundant B-cell epitopes obtained from Bcipep database and equal number of non-epitopes obtained randomly from Swiss-Prot database. The networks have been trained and tested at different input window length and hidden units. Maximum accuracy has been obtained using recurrent neural network (Jordan network) with a single hidden layer of 35 hidden units for window length of 16. The final network yields an overall prediction accuracy of 65.93% when tested by fivefold cross-validation. The corresponding sensitivity, specificity, and positive prediction values are 67.14, 64.71, and 65.61%, respectively. It has been observed that RNN (JE) was more successful than FNN in the prediction of B-cell epitopes. The length of the peptide is also important in the prediction of B-cell epitopes from antigenic sequences. The webserver ABCpred is freely available at www.imtech.res.in/raghava/abcpred/.

Amino Acid Sequence↗
PubMed2006

Mapping of B cell epitopes in measles virus nucleocapsid protein.

The B-cell response against measles nucleoprotein (MeN) plays an important role in the control of measles infection. However, the data on B cell epitopes of MeN are still limited. The objective of this study was to identify B cell epitopes in MeN using monoclonal and polyclonal antibodies raised against recombinant yeast-expressed MeN (rMeN) as well as human sera from measles-positive individuals. After immunization of mice, 15 monoclonal antibodies (mAbs) against rMeN were generated. The B cell epitopes were localized using recombinant overlapping MeN fragments, PepScan analysis, and competitive ELISA. The epitopes of 14 mAbs were mapped within the C-terminus of MeN between amino acids (aa) 419 and 525. Four mAbs recognized a linear epitope located within a sequence of aa 440-448. Competitive ELISA revealed a cluster of conformational mAb epitopes. Cross-inhibition studies with human sera demonstrated similar localization of B cell epitopes recognized by serum antibodies from naturally infected individuals. Thus, the majority of B cell epitopes are located at the C-terminal domain of MeN. These findings provide new data on the antigenic structure of MeN and are in agreement with recent experimental evidence indicating that the C-terminal domain of MeN is well accessible on the surface of nucleocapsid-like structures.

Amino Acid Sequence↗