To understand how bacterial pathogens cause diseases is the most important step in order to prevent the infection and develop an effective treatment. However, the past proceeding studies make us aware of quite-complicated interactions between the host and pathogenic bacteria. Vibrio parahaemolyticus, a food-born pathogen that is a subject of our study, causes inflammatory diarrhea in human upon ingestion of contaminated raw or undercooked seafood. Many virulence factors has been proposed since its discovery in Osaka around 70 years ago, while our research group has revealed that one of these virulence factors, type 3 secretion system 2 (T3SS2), is necessary for diarrhea induced by this bacterium. In addition, we recently found two novel T3SS2 effectors (VopO and VopV) that manipulate the actin cytoskeleton in infected host cells. In this article, I would like to show our findings with regard to biological activities of the effectors and their contributions to the T3SS2-induced enterotoxicity.
Much of what we know about Escherichia coli populations and epidemiology is defined at some level by O serogroups. Moreover, in our collective knowledge, outbreak and disease reports and elsewhere, all information of pathogenic E. coli have O serogroup records. O-serogroup diversification shows a strong association with the genetic diversity of O-antigen biosynthesis genes, and O-serogroup-specific sequences can be used as genetic markers for identifying O serogroups. We sequenced all the known O-antigen biosynthesis gene clusters (O-AGCs) from the 184 E. coli defined O serogroups and determined their genetic makeup and diversity. Subsequently, based on a highly detailed analysis of O-AGCs, we developed comprehensive and practical molecular O-serogrouping platforms; PCR-based “E. coli O-genotuping PCR” and in silico-based “SerotypeFinder”. These simple and exhaustive systems may integrate microbial typing, genomics and evolutionary analyses.