Comparative proteomic analysis on Salmonella Gallinarum and Salmonella Enteritidis exploring proteins that may incorporate host adaptation in poultry Kamelia M. Osman a, ⁎ , Mona M. Ali b , Moustafa I. Radwan b , Hyoung Kyu Kim c , Jin Han c, ⁎ a Department of Microbiology, Faculty of Veterinary Medicine, Cairo University, Giza, Egypt b National Lab for Veterinary Quality Control on Poultry Production, Dokki, Giza, Egypt c Department of Physiology and Biophysics, College of Medicine, Inje University, Busan, Republic of Korea ARTICLE DATA ABSTRACT Article history: Received 13 January 2009 Accepted 18 May 2009 Comparative proteomics analysis of the cytosolic proteins of Salmonella Gallinarum (SG) and Salmonella Enteritidis (SE) isolated from poultry was performed. The constantly detected spots of serovar SG with concomitant absence in SE serovar as well as those markedly over expressed in serovar SE were selected for MALDI-TOF-MS identification. The NCBI-matched proteins that show overregulation were then further confirmed on the mRNA level by quantitative real time PCR. Identified proteins were representing diverse functional activities including energy production, metabolism, and nucleic acid synthesis. Interestingly, some recognized proteins have some relevance to bacterial virulence e.g. Salmonella pathogenicity island 1 effector protein, T-cell inhibitor protein, response regulator protein, paratose synthetase protein (RfbS) and heat shock protein 90. The study revealed the presence of some proteins of unknown function, which raise the speculation for their importance in either host adaptation or pathogenicity among SG serovars. © 2009 Elsevier B.V. All rights reserved. Keywords: Salmonella Gallinarum Salmonella Enteritidis Novel proteins Proteomics Cytosolic proteins 1. Introduction Proteomics, the global analysis of cellular proteins, is a key area of research that is developing in the post-genome era. The application of proteomics provides major opportunities to elucidate disease mechanisms and to identify new diagnostic markers and therapeutic targets. Significant progress has been made in the characterisation of bacterial pathogens using a combination of genomic and proteomic technologies. Patho- genic determinants are identified through comparative pro- teomics between virulent and avirulent isolates whereas complex disease phenotypes can be correlated with specific proteomic signatures identified through the analysis of large collections of natural isolates [1]. In the study of pathogenic bacteria the combined technologies of genomics, proteomics and bioinformatics have provided valuable tools for the study of complex phenomena determined by the action of multiple gene sets [2]. Salmonella bacteria, infamous for food poisoning that kills hundreds of thousands of people worldwide, infect by stealth. They slip unnoticed into and multiply inside of macrophages, the very immune system cells that the body relies on to seek and destroy invading microbes. Members of Salmonella enterica subspecies enterica are mainly associated with warm-blooded vertebrates and are usually transmitted via fecal contamination from infected host. The majority of Salmonella enterica serotypes infect broad variety of animal species including man. Some serotypes, however, are host adapted. These typically cause systemic disease in number of species [3]. Salmonella enterica serovar Gallinarum (SG) is non motile host adapted Salmonella that JOURNAL OF PROTEOMICS 72 (2009) 815 – 821 ⁎ Corresponding authors. Osman is to be contacted at Tel./fax: +20 2 33854762. E-mail addresses: s_mougy@hotmail.com (K.M. Osman), Phyhanj@inje.ac.kr (J. Han). 1874-3919/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.jprot.2009.05.002 available at www.sciencedirect.com www.elsevier.com/locate/jprot