Transcriptome analysis of Vibrio parahaemolyticus in type III secretion system 1 inducing conditions

Abstract

Vibrio parahaemolyticus is an emerging bacterial pathogen capable of causing inflammatory gastroenteritis, wound infections, and septicemia. As a food-borne illness, infection is most frequently associated with the consumption of raw or undercooked seafood, particularly shellfish. It is the primary cause of Vibrio-associated food-borne illness in the United States and the leading cause of food-borne illness in Japan. The larger of its two chromosomes harbors a set of genes encoding type III section system 1 (T3SS1), a virulence factor present in all V. parahaemolyticus strains that is similar to the Yersinia ysc T3SS. T3SS1 translocates effector proteins into eukaryotic cells where they induce changes to cellular physiology and modulate host-pathogen interactions. T3SS1 is also responsible for cytotoxicity toward several different cultured cell lines as well as mortality in a mouse model. Herein we used RNA-seq to obtain global transcriptome patterns of V. parahaemolyticus under conditions that either induce [growth in Dulbecco's Modified Eagle Medium (DMEM) media, in trans expression of transcriptional regulator exsA] or repress T3SS1 expression (growth in LB-S media, in trans exsD expression) and during infection of HeLa cells over time. Comparative transcriptomic analysis demonstrated notable differences in the expression patterns under inducing conditions and was also used to generate an expression profile of V. parahaemolyticus during infection of HeLa cells. In addition, we identified several new genes that are associated with T3SS1 expression and may warrant further study.

Transcriptomic dissection of the horizontally acquired response regulator EsrB reveals its global regulatory roles in the physiological adaptation and activation of T3SS and the cognate effector repertoire inEdwardsiella piscicidaduring infection toward turbot

“…We used RNA-seq analysis to compare the gene expression of E. piscicida grown in DMEM, a condition that mimics bacterial growth during the infection of macrophages, 40,41,42,43 and, to resolve the regulatory role of EsrB, upon EsrB abrogation. These analyses resulted in the finding of a conserved EsrB binding consensus motif in the regulated genes and a repertoire of T3SS-dependent effectors, including 3 established effectors and 6 putative novel effectors that are essential for E. pisicida infection of its host.…”

“…DMEM was used to induce the expression of T3SS and T6SS proteins possibly by mimicry of in vivo or intracellular condition. 40,41,42,43 When grown in LB, there was no apparent growth difference between WT and DesrB, whereas in DMEM, the growth of DesrB was markedly faster than that of WT, suggesting a regulatory role of EsrB in E. piscicida metabolic pathways during growth in DMEM (Figs. S1A and S1B).…”

“…38,39 In this study, we compared the transcriptomes of E. piscicida wild-type and DesrB strains cultured in Dulbecco's Modified Eagle's Medium (DMEM) that induces expression of T3SS and T6SS genes and may mimic conditions encountered during infection of macrophages. 40,41,42,43 This comparison can contribute to a detailed understanding of E. piscicida pathogenesis and the mechanisms underlying its interaction with its hosts.…”

Virulence gene expression of Vibrio parahaemolyticus in the viable but nonculturable state

“…Similarly, Coutard et al (2007b) found that tdh2 was expressed but not upregulated. On the contrary, Coutard et al (2005) and T3SS2 associated genes (translocator genes and their chaperones, regulators, structural, and effector proteins) showed substantial increases over the course of infection in HeLa cells Nydam et al, 2014;Zhou et al, 2009). …”

“…T3SS1 appeared to be responsible for the cytotoxicity to several mammalian cell lines (Burdette et al, 2008;Hiyoshi et al, 2010;Nydam et al, 2014;Zhou et al, 2009) and mortality in a mouse model Pineyro et al, 2010).…”