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Virulence factors of A. actinomycetemcomitans: role in disease, expression regulation, diversity and immune response

Grant number: 03/08598-0
Support type:Research Projects - Thematic Grants
Duration: June 01, 2004 - May 31, 2009
Field of knowledge:Health Sciences - Dentistry
Principal Investigator:Marcia Pinto Alves Mayer
Grantee:Marcia Pinto Alves Mayer
Home Institution: Instituto de Ciências Biomédicas (ICB). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Actinobacillus actinomycetemcomitans is associated to Aggressive periodontitis mostly in its localized form (UP) and to some forms of chronic periodontitis. There is a great diversity among strains of this organism, which can reflect on the virulence of different clones. Genotyping based on ISs mar be an important toll to differentiate the organism, since the hybridization patterns obtained with mobile elements such as IS 150-like is able to detect small differences, and it was indicated to small epidemiological studies of specific subpopulations of A. actinomycetemcomitans. On the other hand, the analysis using a more stable IS would provide a phylogenic analysis. Pulse Field gel electrophoresis is considered the gold standard among methods used to evaluate the phylogenetic structure of a population. The first part of this study aims to analyze the structure of A. actinomycetemcomitans by genotyping a collection of strains isolated in different geographicallocations, including isolates from Brazil, obtained from patients with different periodontal conditions. The phylogenetic structure will be evaluated by PFGE and the relation between the subpopulations will be analyzed through RFLP using ISs probes. The genetic diversity will be related to the polymorphism of a series ofvirulence-associated genes and to the phenotype. Cytolethal distending toxin, encoded by the cdt operon in Actinobacillus actinomycetemcomitans (Mayer et aI, 1999), is the only known bacterial toxin able to induce DNA damage on target cells. We have previousIy shown that the CD toxic titers vary among strains of Actinobacillus actinomycetemcomitans (FABRIS et al, 2002). In addition, a deletion in the promoter of the operon ltx increases the expression of the leukotoxin, and these strains are strongly associated to LJP (Bueno et al, 1998), mostly among patients of African origino the strains will be characterized by the promoter structure of the ltx and cdt operon, and to the polymorphism of the genes aae and apah, involved in adherence and invasion of epithelial cells respectively. Since neither the immune response nor the in vivo production of CDT are currently known, we also aim to purify the three proteins forming the CDT complex (CDTA, CDTB and CDTC) and to determinate the antibodies titles in sera against these proteins in sera from patients exhibiting different periodontal conditions. We could recently demonstrate that the crude extract of a recombinant E. coli expressing AaCDT was able to inhibit NO synthesis by peritoneal macrophages (FERNANDES, 2002). In order to confirm this observation, the effect of CDT proteins on NO production, celI cycle inhibition and cellular distension will be also evaluated. Actinobacillus actinomycetemcomitans presents several outer surfaces proteins, related to virulence. The antibodies titers against the proteins OMP29, OMP 1000 and Aae, those recognized as viru1ence factors will be analyzed in sera of patients with different periodontal conditions. The titers against OMP29 and OMP 100 were associated to infection by the organism. Are was recently described as an adhesin of the bacteria, enabling adhesion to epithelial cells. It is homologous to Hap, produced by Haemophilus influenzae, but some of the properties presented by Hap were not studied in Aae, such as immunogenicity, or adhesion to matrix components as collagen and fibronectin. The gene aae encoding Aae presents variation mostly in number of repeats among strains, which may reflect on the adhesive ability of different strains as well as in its resistance to inhibition by lactoferrin. A knockout mutant of A actinomycetemcomitans deficient in Aae production will be produced and the ability of the mutant to adhere to extracellular matrix compounds will be evaluated and compared to the wild type. Regulation of virulence-associated genes in A. actinomycetemcomitans is very little understood. We aim to produce a knock-out mutant in arcB, a gene that encodes the sensor protein of PREDOX and signs to an OMPR-like (arcA) protein that regulates transcription Quorum sensing system and possibly the Arc system regulate transcription of the operon ltx in A. actinomycetemcomitans. The wild type and the mutant strains will be submitted to various conditions in order to evaluate factors such as adherence, hydrophobicity, production of toxins and outer membrane proteins profile. Transcription of different genes will be evaluated by RT -PCR and a differential display method (RAP-PCR) in the wild type and the mutant strain. (AU)

Scientific publications (9)
(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)
ANA CARLA ROBATTO NUNES; PRISCILA LARCHER LONGO; MARCIA PINTO ALVES MAYER. Influence of Aae Autotransporter Protein on Adhesion and Biofilm Formation by Aggregatibacter actinomycetemcomitans. Brazilian Dental Journal, v. 27, n. 3, p. 255-260, Jun. 2016.
LONGO, P. L.; NUNES, A. C. R.; UMEDA, J. E.; MAYER, M. P. A. Gene expression and phenotypic traits of Aggregatibacter actinomycetemcomitans in response to environmental changes. JOURNAL OF PERIODONTAL RESEARCH, v. 48, n. 6, p. 766-772, DEC 2013. Web of Science Citations: 6.
UMEDA, JOSELY EMIKO; LONGO, PRISCILA LARCHER; LORENZETTI SIMIONATO, MARIA REGINA; ALVES MAYER, MARCIA PINTO. Differential transcription of virulence genes in Aggregatibacter actinomycetemcomitans serotypes. JOURNAL OF ORAL MICROBIOLOGY, v. 5, 2013. Web of Science Citations: 2.
UMEDA, J. E.; DEMUTH, D. R.; ANDO, E. S.; FAVERI, M.; MAYER, M. P. A. Signaling transduction analysis in gingival epithelial cells after infection with Aggregatibacter actinomycetemcomitans. Molecular Oral Microbiology, v. 27, n. 1, p. 23-33, FEB 2012. Web of Science Citations: 13.
PINHEIRO, E. T.; KAWAMOTO, D.; OTA-TSUZUKI, C.; ALMEIDA, L. R. S.; NUNES, A. C. R.; LONGO, P. L.; WIKSTROM, M.; MAYER, M. P. A. Analysis of genotypic variation in genes associated with virulence in Aggregatibacter actinomycetemcomitans clinical isolates. JOURNAL OF PERIODONTAL RESEARCH, v. 46, n. 3, p. 310-317, JUN 2011. Web of Science Citations: 5.
ANDO, E. S.; DE-GENNARO, L. A.; FAVERI, M.; FERES, M.; DIRIENZO, J. M.; MAYER, M. P. A. Immune response to cytolethal distending toxin of Aggregatibacter actinomycetemcomitans in periodontitis patients. JOURNAL OF PERIODONTAL RESEARCH, v. 45, n. 4, p. 471-480, AUG 2010. Web of Science Citations: 14.
KAWAMOTO, D.; ANDO, E. S.; LONGO, P. L.; NUNES, A. C. R.; WIKSTROM, M.; MAYER, M. P. A. Genetic diversity and toxic activity of Aggregatibacter actinomycetemcomitans isolates. Oral Microbiology and Immunology, v. 24, n. 6, p. 493-501, DEC 2009. Web of Science Citations: 23.
LONGO, P. L.; OTA-TSUZUKI, C.; NUNES, A. C. R.; FERNANDES, B. L.; MINTZ, K.; FIVES-TAYLOR, P.; MAYER, M. P. A. Aggregatibacter actinomycetemcomitans arcB INFLUENCES HYDROPHOBIC PROPERTIES, BIOFILM FORMATION AND ADHESION TO HYDROXYAPATITE. Brazilian Journal of Microbiology, v. 40, n. 3, p. 550-562, SEP 2009. Web of Science Citations: 2.
PL LONGO; C OTA-TSUZUKI; ACR NUNES; BL FERNANDES; K MINTZ; P FIVES-TAYLOR; MPA MAYER. Aggregatibacter actinomycetemcomitansarcB influences hydrophobic properties, biofilm formation and adhesion to hydroxyapatite. Brazilian Journal of Microbiology, v. 40, n. 3, p. -, Set. 2009.

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