Salmonella enterica: genetic variability and origin of the serotype 4,[5],12:i:- in Brazil and development of attenuated mutants of S. enterica Enteritidis

• Grant number: 09/15956-7
• Support Opportunities: Regular Research Grants
• Start date: April 01, 2010
• End date: September 30, 2012
• Field of knowledge: Biological Sciences - Microbiology - Applied Microbiology
• Principal Investigator: Marcelo Brocchi
• Grantee: Marcelo Brocchi
• Host Institution: Instituto de Biologia (IB). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil

Abstract

The pathogenic serovars of Salmonella enterica can cause illness in mammals varying from gastrointestinal to systemic infections, depending on the bacterial serovar and the host infected. It was described more than 2500 serovars of S. enterica so far. The serovars Typhimurium and Enteritidis are common human pathogens. A new emergent pathogenic serotype has been frequently isolated from human infections since the end of the last century and in different countries such as United States, Spain, Thailand, Luxemburg, and Brazil. This new serotype is typed as S. enterica I 4,[5],12:i:-. It presents serological and physiological characteristics almost identical to the serovar Typhimurium (S. enterica I 4,[5],12:i:1,2) but it does not exhibit the flagellar phase variation typical of this last serovar. It is also similar serologically to serovar Lagos (S. enterica I 4,[5],12:i:1,5). In the State of São Paulo, Brazil, 4,[5],12:i:- was the third serotype more frequently isolated from human infections between 1996 and 2003.Previously, results obtained in our laboratory indicated that 4,[5],12:i:- strains isolated in Brazil are originated from serovar Typhimurium by the deletion of genes involved in the flagellar phase variation. However, these data were obtained by typing methods such as Rep-PCR and Pulsed Field. Considering the epidemiological importance of this serotype worldwide, the aim of this study is to characterize further this serotype. Therefore, the genetic similarity of the serotype 4,[5],12:i:- with Typhimurium will be evaluated by DNA sequence methodologies such as Multilocus sequence typing (MLST). Therefore, it will be possible to compare the sequence of some genes obtained in this study with sequences present in the MLST database. We will also investigate the stability of the genomic region flanking the fljBA operon, testing one hypothesis for the origin of this new serotype. Also, a S. enterica 4,[5],12:i:- strain will be partially sequenced and its genome will be compared with the genomes of serovar Typhimurium and the S. enterica 4,[5],12:i:- CVM23701, a strain isolated in the United States that is also been sequenced.Recent data of our lab indicate that S. enterica Typhimurium mutant strains with deletions of himA ou himD that encodes the Integration Host Factor (IHF) and fis (Factor for Inversion Stimulation) are attenuated and immunogenic in the mouse model of infection, constituting potential S. enterica vaccine strains. Considering these results, another objective of this project is the construction of ”himA, ”himD and ”fis mutant strains of the serovar Enteritidis, evaluating the attenuation of virulence and the protective potential of them in the murine model of infection. (AU)

Scientific publications

(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)

TOMIYAMA, M. P. O.; WERLE, C. H.; MILANEZ, G. P.; NOBREGA, D. B.; PEREIRA, J. P.; CALARGA, A. P.; FLORES, F.; BROCCHI, M.. Salmonella enterica Typhimurium fljBA operon stability: implications regarding the origin of Salmonella enterica I 4,[5], 12:i:-. Genetics and Molecular Research, v. 14, n. 4, p. 19057-19065, 2015. (09/15956-7, 14/11280-7, 13/11880-1, 12/10608-3, 12/05382-6)

Filed patent(s) as a result of this research project