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At least 19 recordsLinked to original sources
PubMed2026

Genetic polymorphism in Plasmodium falciparum MSPDBL1 and MSPDBL2 and their impact on B- and T-cell immunodominant epitopes in Brazilian malaria-endemic areas.

Merozoite Surface Protein Duffy Binding-like 1 and 2 (MSPDBL1 and MSPDBL2) are involved in erythrocyte invasion by Plasmodium falciparum. Antibodies targeting PfMSPDBL1 and PfMSPDBL2 show strong opsonizing and growth-inhibitory activities, supporting their potential as asexual blood-stage vaccine candidates. Given that the extensive genetic diversity of P. falciparum contributes to immune evasion, identifying polymorphisms in regions encoding PfMSPDBL1 and PfMSPDBL2 is essential to assess their relevance as vaccine targets. In this study, we investigated polymorphisms in the pfmspdbl1 and pfmspdbl2 genes and their impact on potentially antigenic regions within the Duffy Binding-like (DBL) and Secreted Polymorphic Antigen Associated with Merozoite (SPAM) domains. Blood samples were collected from 47 P falciparum-infected individuals from three malaria-endemic areas of the Brazilian Amazon. Genomic DNA was extracted, PCR-amplified, and sequenced. Intrapopulation genetic diversity and Tajima's D values were estimated using bioinformatics tools. Linear B- and T-cell epitopes were predicted using BCPreds and IEDB (Immune Epitope Database), respectively. Two and thirty-two polymorphisms were identified in pfmspdbl1 within the SPAM and DBL domains, respectively, whereas pfmspdbl2 presented two polymorphisms across both domains and a 12 bp insertion in the SPAM domain. Tajima's D values were positive across domains, except for the DBL domain of pfmspdbl2 in Mâncio Lima. Fifteen B-cell and fifteen T-cell epitopes were predicted, with polymorphisms in three B-cell epitopes affecting Vaxijen scores. Together, these findings reveal contrasting evolutionary patterns between PfMSPDBL1 and PfMSPDBL2, with potential implications for antigenicity, and highlight PfMSPDBL2 as a potential candidate for further evaluation in multicomponent blood-stage malaria vaccine development.

Genetic diversity↗
PubMed2016

Identification of food-grade subtilisins as gluten-degrading enzymes to treat celiac disease.

Gluten are proline- and glutamine-rich proteins present in wheat, barley, and rye and contain the immunogenic sequences that drive celiac disease (CD). Rothia mucilaginosa, an oral microbial colonizer, can cleave these gluten epitopes. The aim was to isolate and identify the enzymes and evaluate their potential as novel enzyme therapeutics for CD. The membrane-associated R. mucilaginosa proteins were extracted and separated by DEAE chromatography. Enzyme activities were monitored with paranitroanilide-derivatized and fluorescence resonance energy transfer (FRET) peptide substrates, and by gliadin zymography. Epitope elimination was determined in R5 and G12 ELISAs. The gliadin-degrading Rothia enzymes were identified by LC-ESI-MS/MS as hypothetical proteins ROTMU0001_0241 (C6R5V9_9MICC), ROTMU0001_0243 (C6R5W1_9MICC), and ROTMU0001_240 (C6R5V8_9MICC). A search with the Basic Local Alignment Search Tool revealed that these are subtilisin-like serine proteases belonging to the peptidase S8 family. Alignment of the major Rothia subtilisins indicated that all contain the catalytic triad with Asp (D), His (H), and Ser (S) in the D-H-S order. They cleaved succinyl-Ala-Ala-Pro-Phe-paranitroanilide, a substrate for subtilisin with Pro in the P2 position, as in Tyr-Pro-Gln and Leu-Pro-Tyr in gluten, which are also cleaved. Consistently, FRET substrates of gliadin immunogenic epitopes comprising Xaa-Pro-Xaa motives were rapidly hydrolyzed. The Rothia subtilisins and two subtilisins from Bacillus licheniformis, subtilisin A and the food-grade Nattokinase, efficiently degraded the immunogenic gliadin-derived 33-mer peptide and the immunodominant epitopes recognized by the R5 and G12 antibodies. This study identified Rothia and food-grade Bacillus subtilisins as promising new candidates for enzyme therapeutics in CD.

Bacteria↗
PubMed2026

Characterisation of HIV-1 Gag Cytotoxic T-Lymphocyte Epitopes in the Southern African Region-A Systematic Review.

During early HIV-1 infection, robust Cytotoxic T-lymphocyte (CTL) responses are mostly targeted at immunodominant Gag p24 epitopes to reduce HIV-1 viraemia to a set-point. The aim of this study was to review the current body of knowledge on HIV-1 Gag CTL epitopes in the southern African region where subtype C is prevalent. Peer-reviewed records were obtained from three databases: PubMed Central, Web of Science Core Collection, and Scopus, using the following search terms: HIV subtype C Gag epitopes, and HIV clade C Gag epitopes. The search results were restricted to countries within the southern African region, and only data published in English and between the years 2000-2025 were considered for this review. The search from the three databases produced a total of 2103 peer-reviewed records, and 49 records were included in the review. The majority of studies (58.44%) were conducted in South Africa, followed by Botswana (15.58%), Zambia (10.39%), Malawi (7.79%), Zimbabwe (6.49%) and Angola (1.30%). There were no studies identified from other southern African countries. A total of 60 Gag CTL epitopes were identified, of which 17 (28.33%) were located within the matrix protein (p17), 33 (55.00%) within the capsid protein (p24), and 4 (6.67%) within the Gag polyprotein (p2p7p1p6). The commonly detected immunodominant epitopes were mostly located within the Gag p24 protein; and included TPQDLNTML (TL9, Gag p24 48-56) and TSTLQEQIGW (TW10, Gag p24 108-117) present at 16.00% and 13.3%, respectively. The proportion of HLA-A, B and C allotypes in this systematic review were 18%, 78%, and 4%, respectively. The more common HLA-B allotypes that restrict immunodominant Gag epitopes and facilitate better control of HIV-1 were HLA-B*57, -B*58:01, -B*42:01 and -B*81:01. This systematic review has provided important insights into the description of immunodominant Gag epitopes and HLA-I alleles that contribute to the control of HIV-1 viraemia in the southern African region. It has also exposed that some CTL epitopes identified in the southern African studies are not reported on the Los Alamos HIV database (LANL HIV database). This highlights a need to have this database updated with this information as it is used as a reference for epitopes. This review could provide insights into the design of an epitope-based HIV-1 vaccine that would also be effective in the southern African region.

Humans↗
PubMed2025

HLA-B Serine 116 Confers Protection Against Severe COVID-19 in a Cohort From Rio de Janeiro, Brazil.

COVID-19 is a respiratory disease caused by SARS-CoV-2, in which severe outcomes are primarily driven by an exacerbated immune response. The HLA region has been extensively investigated in COVID-19 due to its central role in the immune response, although genetic associations vary across populations. Here, the association of HLA genetic variability with COVID-19 severe respiratory outcomes was investigated in an admixed population from Rio de Janeiro, Brazil. Results of a comparative study between mild and severe COVID-19 cases involving 306 individuals have suggested risk associations with severe COVID-19 for the HLA-DPB1*13:01 allele (OR = 3.42, 95% CI = 1.05-11.16, p = 0.041) and the HLA-B*39 allele group (OR = 3.26, 95% CI = 1.16-9.13, p = 0.024), although statistical significance was lost after FDR adjustment for multiple comparisons (adjusted p > 0.05). Amino acid analyses showed that a serine at position 116 of HLA-B conferred protection against severe COVID-19 (OR = 0.4774, 95% CI = 0.28-0.81, p = 0.006, adjusted p = 0.031). In silico analysis using the NetMHCpan tool predicted that this residue, located in the HLA-B peptide-binding groove, has enhanced binding affinity to immunodominant SARS-CoV-2 epitopes, suggesting a functional mechanism underlying the observed protection. The association of single nucleotide variants at the HLA region was also investigated, and no statistically significant association was found. Results obtained in the present study underscore the importance of HLA in COVID-19 severity, likely mediated by its influence on viral peptide presentation, and advance our understanding of the genetic underpinnings of severe disease in admixed populations.

Humans↗
PubMed2026

Immunodominant Tuberculosis Antigens Recognized by Human CD4+ and CD8+ T Cells.

Tuberculosis (TB), caused by infection with Mycobacterium tuberculosis (MTB), represents an important cause of morbidity and mortality worldwide for which an improved vaccine and immunodiagnostics are urgently needed. CD4+ and CD8+ T cells play an important role in host defense to TB. Definition of the immunodominant antigens recognized by these T cells is critical for improved understanding of the immunobiology of TB and for development of vaccines and diagnostics. Herein, we review antigens and epitopes recognized by classically human leukocyte antigen (HLA) class I- and class II-restricted CD4+ and CD8+ T cells in humans infected with MTB, as defined using either targeted or genome-wide approaches. We address the extent to which these antigens have been defined as immunodominant, protective, and/or specific to disease stages in humans and, with particular relevance to CD8+ T-cell recognition, whether these antigens are displayed by MTB-infected cells.

Journal Article↗
PubMed1976

Immunochemical analysis of distinct cellular antigens isolated from a nontypable bovine strain of group B streptococci.

Four immunologically distinct antigens were isolated from a bovine strain of group B streptococci, designated 14 Mi. Chemical analysis indicated that two of the cell surface antigens consisted of glucose, galactose, and glucosamine, whereas the other cell surface antigen, an acidic protein, contained a predominance of aspartic acid, glutamic acid, and alanine. A cell wall-associated triheteroglycan consisting of galactose, glucose, and glucosamine was isolated from strain 14 Mi by 10% trichloroacetic acid. Immunochemical studies suggested that this glycan is type specific and consists of an immunodominant alpha-linked galactosyl-glucose disaccharide.

Animals↗
PubMed1979

Structural studies on the immunodominant group of lipid A from lipopolysaccharide of Yersinia pseudotuberculosis.

Lipid A isolated from lipopolysaccharide of Yersinia pseudotuberculosis was used for immunization of rabbits to afford antisera to lipid A with titers of 1:640 in the passive hemolysis test. Exhaustion of immune serume with sheep erythrocytes decreased antibody titers up to 1:160. Authentic samples of 2-(DL-3-hydroxytetradecanoyl)amino-2-deoxy-D-glucose 6-phosphate, 2-tetradecanoylamino-2-deoxy-D-glucose 6-phosphate and 2-acetamido-2-deoxy-D-glucose 6-phosphate have been synthesized in order to carry out a comparative study of inhibitory activity of these compounds and lipid A using a system of lipid A and antiserum to lipid A. As a result, the immunodominant moiety of the lipid A of Y. pseudotuberculosis proved to contain a D-glucosamine residue acylated with 3-hydroxytetradecanoic acid at the amino group. The nature of the fatty acid acylating the amino group of glucosamine does not play an important role in the structure of immunodominant moiety of lipid A.

Animals↗
PubMed1979

Studies on immune tolerance to heat-aggregated human IgG in rabbits: its relevance to the production of rheumatoid factors.

Rabbits neonatally tolerized with native monomeric human IgG and subsequently immunized with heat-aggregated human IgG emulsified in Freund's complete adjuvant, at a time when B cells but not T cells should have spontaneously recovered from tolerization, resulted in the production of an antibody resembling human rheumatoid factors directed against a single antigenic determinant in the Fc region of the IgG molecule. Rabbits immunized in an identical fashion after adult tolerization treatments failed to respond during the period corresponding to B-cell tolerance, but subsequently produced antibody or similar specificity to that produced by neonatally tolerized animals. These results indicate that no completely new antigenic determinants are created on heat aggregation of IgG, but there appears to be some potentiation of immunodominance of an already existing determinant. A possible mechanism for the production of rheumatoid factors in rheumatoid arthritis is suggested.

Animals↗
PubMed1976

[The biochemical aspects of blood group antigens].

The biochemical aspects of the immunodominant structures of blood groups antigens are mainly restricted to the following: ABH and Lewis in secretory fluids or on the red blood cells; P system (P1, P, Pk antigens); MN antigens and related; Tn and Tn antigens; Some hypothesis may be put forward for the I, i antigens. Many other antigens seem to be on the dependence of interactions between proteins and lipids of the red cell membrane; such immunodominant structures are not yet known. Except for the ABH and Lewis groups, the biosynthesis pathways are at present unclear.

ABO Blood-Group System↗
PubMed1976

[Study of a specific polyoside and a group antigen extracted from Leptospira biflexa patoc, patoc I strain].

We extracted from L. biflexa patoc a fraction F, reacting in hemagglutination and ring tests with sera prepared against more than ten different serogroups. This fraction contains mainly a polysaccharide (65 per cent), the role of which was clearly demonstrated in the precipitation reaction with homologous antisera, through periodic oxidation; it also contains lipids (20 per cent) and proteins (10 per cent). We isolated from this fraction F, by Biogel column chromatography, 2 distinct antigens, one, F2, carrying the patoc-type specificity, the other, F 1B, a group specificity shared by many leptospira. These antigens differ not only immunogically, but also in their chemical composition. The type-specific antigen F2 contains mainly a polysaccharide composed of arabinose and glucosamine (possibly an immunodominant sugar). As for the group-specific fraction F 1B, its composition is more complex since lipids and proteins are also found with the polysaccharide. This antigen could therefore be a lipoglycoprotein.

Animals↗
PubMed1978

Existence of multiple immunodeterminants in the type-specific capsular substance of group B type Ia streptococci.

Rabbits immunized with group B, type Ia streptococci produce two distinct populations of protective antibodies. Evidence is presented indicating that these antibodies are directed against two major immunodeterminants which coexist in the specific type Ia antigen. Immunochemical data, using purified antibody preparations, indicate that the type substance, a sialic acid polymer consisting of galactose, glucose, glucosamine, and sialic acid, possesses two distinct immunodominant determinants, terminal sialic acid residues and a galactosyl oligosaccharide. Antibodies directed against either of these determinants were shown to possess in vivo and in vitro opsonic capabilities.

Animals↗
PubMed1977

[Immunochemical study of the lipoprotein substance Pg (author's transl)].

Site Pg is an antigenic determinant which is present on the surface of serum lipoproteins and reacts with an antilpoprotein myelomatous immunoglobulin, the IgA, Ger. Firstly site Pg is extracted from LDL with the major part of lipids, by an ether-methanol mixture at 6 p. 100. Then the organic substrate obtained is evaporated under vacuum and dissolved in saline before being submitted to an extraction by ehter only. Under these conditions, site Pg remains in the aqueous phase. A polyacrylamide gel filtration on Biogel P2 allows then to separate the substance which reacts with IgA Ger. anti-Pg, from the aqueous phase. The identification of site Pg allowed us to recognize the presence of galactose, phosphorus and choline, and to evaluate its molecular weight of about 330. The reactivity of site Pg with IgA anti-Pg was measured by inhibition of passive hemagglutination and fluorescence quenching. The association constant of site Pg with the whole IgA Ger. or with its Fab fragment could thus be calculated (1.6 10(5) M-1 with the whole IgA; 2.3 10(5) M-1 with the Fab fragment). We showed also that if phosphorylcholine plays an immunodominant role, the presence of sugar seems necessary, since the association constant of the whole IgA Ger. with site Pg is higher than that of IgA Ger. with phosphorylcholine alone.

Binding Sites, Antibody↗
PubMed1978

Specificity of antisera from Lewis rats immunized with encephalitogenic fragment 43-88 of guinea pig myelin basic protein.

Inbred Lewis rats were immunized with encephalitogenic fragment 43-88 of guinea pig myelin basic protein emulsified in complete Freund's adjuvant. After recovery from experimental allergic encephalomyelitis (EAE) the animals were given a booster immunization, bled, and the specificity of the individual anti-fragment antisera was examined by direct binding assays by using radioiodinated fragment 43-88 and peptides 43-67, 68-88, and 79-88. Competitive-binding experiments with these peptides in competition with labeled fragment 43-88 were also done. The results of these experiments indicated that the immunodominant region of fragments 43-88 was the carboxy-terminal half of the molecule. Individual antisera recognized different antigenic determinants within this region.

Animals↗
PubMed1975

Antigenic determinants of hen egg-white lysozyme in delayed hypersensitivity. I. Macrophage migration inhibition activities of lysozyme fragments.

Five kinds of fragments of hen egg-white lysozyme (HL) were tested by macrophage migration inhibition (MMI) assay using peritoneal exudate cells (PEC) of guinea pigs immunized with HL in complete Freund's adjuvant. (See article). These four kinds of HL fragments were also shown to be composed of the immunodominant groups of the HL molecule for circulating antibody against HL in guinea pigs. The relationships between the antigenic sites related to circulating antibody and the cellular recognition sites are discussed.

Animals↗