Proteomic Analysis of Virulence Profiles in Clinical Strains of Shigella flexneri in Manaus – Amazon State

Abstract

Background: Shigella is a Gram-negative bacterium and belongs to Enterobacteriaceae family. These bacteria have been described as responsible for many diarrheic infections around the world and affects children as 5 years old. As a striking feature of these bacteria, we can say about the invasive capacity and the severe damage in the intestine of the host. Epidemiological studies conducted during 2007 to 2009 by our research group, Diagnosis and Control of Infectious Diseases of the Amazon - DCDIA, identified Shigella as the 4th most frequent bacterial pathogen in children with diarrhea treated in public hospitals in Manaus - AM. To understand the mechanisms of pathogenesis of these clinical strains, and to describe the mechanisms of cellular invasion, this study proposes the identification of the proteome of two isolates, through the mass spectrometry coupled to liquid chromatography. The clinical strains were submitted to experimental conditions that mimic the epithelial cellular contact in the host, using the inductor Congo Red, in order to investigate which proteins are being produced by this pathogen. Results: The proteomic profile of Shigella strain 201 reveals 386 intracellular proteins cultivated in LB medium and 189 intracellular proteins cultivated using the Congo Red inductor. For the M90T strain, a total of 470 intracellular proteins were detected in LB medium and 383 intracellular proteins cultivated with Congo Red. The findings reveal that proteins exclusively induced by Congo Red in the clinical strain are related to virulence processes, such as IpaC and IpaD proteins, which have already been extensively investigated in the literature. Conclusions: However, new target proteins are pointed out, such as Hmp, YkfE, AepA, MobC, MetK, OsmY, LptA and LuxS which are classified as proteins predicted as pathogenic, based on our analyses. Although such proteins are involved in the virulence of enteric pathogens, their functions are still little explored or inexistent for the Shigella genus, mainly in the northern region of Brazil. We expected this work to reveal the mechanisms underlying the isolated clinical strains and elucidate new effectors and how they modulate the pathogenesis of these bacteria.