Differential Virulence Gene Expression of Group A Streptococcus Serotype M3 in Response to Co-Culture with Moraxella catarrhalisReportar como inadecuado




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Streptococcus pyogenes group A Streptococcus, GAS and Moraxella catarrhalis are important colonizers and opportunistic pathogens of the human respiratory tract. However, current knowledge regarding colonization and pathogenic potential of these two pathogens is based on work involving single bacterial species, even though the interplay between respiratory bacterial species is increasingly important in niche occupation and the development of disease. Therefore, to further define and understand polymicrobial species interactions, we investigated whether gene expression and hence virulence potential of GAS would be affected upon co-culture with M. catarrhalis. For co-culture experiments, GAS and M. catarrhalis were cultured in Todd-Hewitt broth supplemented with 0.2% yeast extract THY at 37°C with 5% CO2 aeration. Each strain was grown in triplicate so that triplicate experiments could be performed. Bacterial RNA was isolated, cDNA synthesized, and microarray transcriptome expression analysis performed. We observed significantly increased ≥4-fold expression for genes playing a role in GAS virulence such as hyaluronan synthase hasA, streptococcal mitogenic exotoxin Z smeZ and IgG endopeptidase ideS. In contrast, significantly decreased ≥4-fold expression was observed in genes involved in energy metabolism and in 12 conserved GAS two-component regulatory systems. This study provides the first evidence that M. catarrhalis increases GAS virulence gene expression during co-culture, and again shows the importance of polymicrobial infections in directing bacterial virulence.



Autor: Suzanne J. C. Verhaegh , Anthony R. Flores, Alex van Belkum, James M. Musser, John P. Hays

Fuente: http://plos.srce.hr/



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