			Home About us Contact

Antigen I/II (antigen + ii)

Distribution by Scientific Domains

Medical Sciences	50%

Selected Abstracts

The changing faces of Streptococcus antigen I/II polypeptide family adhesins

MOLECULAR MICROBIOLOGY, Issue 2 2010
L. Jeannine Brady
Summary Streptococcus mutans antigen I/II (AgI/II) protein was one of the first cell wall-anchored adhesins identified in Gram-positive bacteria. It mediates attachment of S. mutans to tooth surfaces and has been a focus for immunization studies against dental caries. The AgI/II family polypeptides recognize salivary glycoproteins, and are also involved in biofilm formation, platelet aggregation, tissue invasion and immune modulation. The genes encoding AgI/II family polypeptides are found among Streptococcus species indigenous to the human mouth, as well as in Streptococcus pyogenes, S. agalactiae and S. suis. Evidence of functionalities for different regions of the AgI/II proteins has emerged. A sequence motif within the C-terminal portion of Streptococcus gordonii SspB (AgI/II) is bound by Porphyromonas gingivalis, thus promoting oral colonization by this anaerobic pathogen. The significance of other epitopes is now clearer following resolution of regional crystal structures. A new picture emerges of the central V (variable) region, predicted to contain a carbohydrate-binding trench, being projected from the cell surface by a stalk formed by an unusual association between an N-terminal ,-helix and a C-terminal polyproline helix. This presentation mode might be important in determining functional conformations of other Gram-positive surface proteins that have adhesin domains flanked by ,-helical and proline-rich regions. [source]

Host collagen signal induces antigen I/II adhesin and invasin gene expression in oral Streptococcus gordonii

MOLECULAR MICROBIOLOGY, Issue 2 2003
Catherine Heddle
Summary Microbial interactions with host molecules, and programmed responses to host environmental stimuli, are critical for colonization and initiation of pathogenesis. Bacteria of the genus Streptococcus are primary colonizers of the human mouth. They express multiple cell-surface adhesins that bind salivary components and other oral bacteria and enable the development of polymicrobial biofilms associated with tooth decay and periodontal disease. However, the mechanisms by which streptococci invade dentine to infect the tooth pulp and periapical tissues are poorly understood. Here we show that production of the antigen I/II (AgI/II) family polypeptide adhesin and invasin SspA in Streptococcus gordonii is specifically upregulated in response to a collagen type I signal, minimally the tri-peptide Gly-Pro-Xaa (where Xaa is hydroxyproline or alanine). Increased AgI/II polypeptide expression promotes bacterial adhesion and extended growth of streptococcal cell chains along collagen type I fibrils that are characteristically found within dentinal tubules. These observations define a new model of host matrix signal-induced tissue penetration by bacteria and open the way for novel therapy opportunities for oral invasive diseases. [source]

Analysis of Streptococcus mutans biofilm proteins recognized by salivary immunoglobulin A

MOLECULAR ORAL MICROBIOLOGY, Issue 5 2009
T. Sanui
Introduction:, The purpose of this study was to examine the Streptococcus mutans biofilm cellular proteins recognized by immunoglobulin A (IgA) in saliva from various caries-defined populations. Methods:, Biofilm and planktonic S. mutans UA159 cells were prepared. The proteins were extracted, separated by two-dimensional gel electrophoresis, transferred to blotting membranes, and probed for IgA using individual saliva samples from three groups of subjects; those who developed 0 caries (no active caries), 5,9 caries (medium), or more than 10 caries (severe) over a 12-month interval. Results:, Several proteins were recognized by salivary IgA in all groups of saliva but spot distribution and intensity varied greatly between the groups, and some proteins were recognized more strongly in biofilm cells than in planktonic culture, and vice versa. Furthermore, 15 proteins were only recognized by saliva from the ,no active caries' group, and four proteins were recognized by saliva samples from subjects in all three groups. Specifically, antigen I/II was recognized less in biofilm cells by caries-free saliva compared with planktonic cells. However, salivary IgA antibody to antigen I/II was absent in blots using saliva from the ,medium caries' and ,severe caries' groups. Conclusion:, The bacterial molecules recognized by caries-free saliva are significant factors for S. mutans caries formation, and their inhibition could be a therapeutic target. In addition, saliva of caries-free subjects includes significant IgA antibody against antigen I/II of S. mutans, indicating a protective mechanism. However, microorganisms may protect themselves from host immune attack by forming biofilms and decreasing expression of antigen I/II. [source]

Bullous pemphigoid antigen II (BP180) and its soluble extracellular domains are major autoantigens in mucous membrane pemphigoid: the pathogenic relevance to HLA class II alleles and disease severity

BRITISH JOURNAL OF DERMATOLOGY, Issue 1 2006
N. Oyama
Summary Background, Mucous membrane pemphigoid (MMP), a chronic autoimmune subepithelial blistering disease, is associated with circulating IgG and/or IgA autoantibodies against several basement membrane zone antigens. The heterogeneity of clinical presentation and diversity of target autoantigens have contributed to difficulties in characterizing this condition immunologically. Objectives, To analyse serum autoantibody profile and HLA class II alleles in MMP patients and to correlate this with the clinical presentation of disease. Methods, Well-defined subgroups consisting of 124 patients with MMP were examined for IgG and IgA reactivity with immunoblotting using human epidermal, dermal and placental amnion proteins. The results were further analysed on the basis of detailed clinical (sites of involvement and disease severity) and immunopathological criteria (immunofluorescence study and HLA class II alleles). Results, Immunoblot assay revealed that the majority of MMP patients had IgG (93 of 124, 75%) and/or IgA autoantibodies (63 of 124, 51%) to BP180 (including its soluble ectodomains, 120-kDa LAD-1 and 97-kDa LABD97 antigens). Other antigens targeted predominantly by IgG autoantibodies included: BP230 in 34 (27%), ,4 integrin in 26 (21%), and laminin 5 in three (2%). All the BP230+ sera and 23 (88%) ,4 integrin+ sera also reacted with at least one of the BP180 antigens. Over 85% of patients with reactivity to ,4 integrin had ocular involvement. In most cases of MMP, more severe clinical features were associated with antibody reactivity to multiple basement membrane zone antigens, as well as reactivity to multiple BP180 component antigens. Dual BP180/LAD-1 reactivity with IgG and IgA was associated with a more severe phenotype. In addition, the subset-dependent autoantibody reactivity correlated well with specific HLA class II alleles, DQB1*0301, DRB1*04 and DRB1*11. Conclusions, Our results confirmed that BP180 is a major autoantigen targeted by the sera of patients with MMP. The disease-prevalent HLA class II alleles and humoral autoimmune response against the particular subsets of antigenic epitope(s) within BP180 ectodomain may contribute to the clinicopathological significance and disease severity of MMP. [source]