Dr Maria Teresa Muniesa, Associate Professor, Department of Genetics, Microbiology and Statistics, University of Barcelona, will present a seminar entitled : Stx phages: What do we know so far?

Host:     Stephanie Schuller

Abstract:
The E. coli genomes contain one or more prophages, many of which encode toxin genes. Among them, Stx phages are the most relevant because they encode the Shiga toxin, considered the main virulence character of EHEC and the toxin is responsible for the most serious complications of EHEC-associated diseases, such as Hemolytic uremic syndrome.

Stx phages are genetically and morphologically heterogeneous and, after induction of their lytic cycle, they are abundant as free virions in many extraintestinal environments, water samples, human and animal feces, soil, and food samples, including vegetables and minced meat. The efficient spread of stx genes by means of the highly persistent Stx phages increases the chances of generating new EHEC strains.

The benefits of Stx production and Stx phage induction for EHEC has been proposed and several advantages can be envisaged, but it is still intriguing considering that the phage induction, leading to an increase in Stx production and virulence potential, ultimately causes cell death. The problem is indeed real if the scenario is observed at “cell level”, but the situation changes from the perspective of bacterial population. EHEC population is heterogeneous also in terms of phage induction, and only a fraction of the population induces Stx phages and dies, while the prevailing fraction of cells remains uninduced, even under inducing conditions. This provides obvious advantages for the bacterial population as a whole.

All staff from organisations on the Norwich Research Park are welcome to attend.