Summer Research Fellowship Programme of India's Science Academies

Comparing the expression of important virulence genes in the vaccine strain versus the wild type strain of Salmonella enterica serovar Typhimurium

Varsha U Kamath

PES University, 100 Feet Ring Road, Banshankari 3rd Stage, Bangalore 560085

Dr Dipshikha Chakravortty

Indian Institute of Science, CV Raman Road, Bengaluru, Karnataka 560012


One of the primary enteric pathogens that infects both humans and animals is the bacterium Salmonella. Ingestion of contaminated food or water leads to this bacterial infection. Salmonellae, after reaching the intestinal epithelium, trigger gastrointestinal diseases. The pathogen, in some patients, can disseminate to other organs after invading the intestinal epithelium. This results in the infection spreading to other parts of the body. In such cases, antimicrobial therapy is prescribed. In this therapy, drugs based on Fluoroquinolones and expanded spectrum Cephalosporin are administered. The Salmonella chromosome consists of several virulence mechanisms which take part in its pathogenicity. Genes located within the so-called Salmonella Pathogenicity Islands (SPIs) are the most important in terms of virulence. A few other factors or traits which contribute to the success of the pathogen within the host are pSLT virulence plasmids, adhesins, flagella, and biofilm related proteins. This system has several regulatory mechanisms which synchronize all these elements to guarantee bacterial survival in the host. Statistically, the rate of infection caused by Salmonella is very high and is shooting up day by day, costing many lives. This disease mostly claims children, geriatrics and the immunocompromised. Currently, only two vaccines are widely available against Salmonella. Yet, neither of them has been implemented at the country level. The need for efficient vaccines and therapeutics which resolve all the issues posed by the currently available vaccines is the need of the hour. STM ∆X pACDH Y has been previously shown to confer protection against the virulent STM strain in the lab. My research aimed to compare the expression of some important virulence genes in the vaccine strain and the wild type strain of Salmonella enterica serovar Typhimurium (to further study the vaccine potent of the vaccine strain). This virulence profiling was done by performing Quantitative PCR.

Keywords: Salmonella, gastrointestinal, Fluroquinolones, Cephalosporin, virulence, Salmonella Pathogenicity Islands, Quantitative PCR.

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