Project description:Vibrio parahaemolyticus is a Gram-negative bacterium commonly found in marine and estuarine environments. Acute hepatopancreatic necrosis disease (AHPND) caused by this bacterium is an ongoing problem among shrimp farming industries. V. parahaemolyticus proteins PirA and PirB have been determined to be major virulence factors that induce AHPND. In this study, Pacific white shrimp (Litopenaeus vannamei) were challenged with recombinant PirA and PirB by a reverse gavage method and then at 30 m, 1, 2, 4, and 6 h time points, the hepatopancreas of five individual shrimp were removed and placed into RNA later. We conducted RNA sequencing of the hepatopancreas samples from a no PirA/B control (n = 5) and PirA/B-treated shrimp at the different time intervals (n=5). We evaluated the different gene expression patterns between the time groups to the control with a focus on identifying differences in innate immune function.
Project description:Compare the secreted proteins of a wild-type Vibrio parahaemolyticus strain with those of a mutant in hcp2, rendering the T6SS2 inactive
Project description:Comparative proteomics to identify proteins found in the media of Vibrio parahaemolyticus RIMD 2210633 bacteria with an active T6SS2 compared to bacteria with inactive T6SS2. Bacteria with an active T6SS2 are Vibrio parahaemolyticus RIMD 2210633 inwhich hcp1 was deleted to inactivate T6SS1. T6SS2 inactive bacteria are the former strain with an additional deletion in hcp2. Both strains express TfoX from an arabinose-inducible plasmid to induce T6SS2 activity.
Project description:The quorum regulatory cascade is poorly characterized in Vibrio parahaemolyticus, in part because swarming and pathogenicity - the hallmark traits of the organism - are repressed by this scheme of gene control. As a consequence, many isolates appear silenced for quorum sensing via phase variation. In these studies, we examine a swarm proficient, virulent strain and find an altered function allele of the central quorum regulator luxO. We use this allele, which produces a constitutively active LuxO, to probe the upstream elements of the pathway and demonstrate their functionality for the first time. We find that the state of luxO affects expression of three small regulatory RNAS (Qrrs) and the activity of a translational fusion in opaR, the central output regulator. We use microarray profiling to determine the OpaR regulon, which was found to encompass ~5.2% of the genome. The quorum sensing proficient strain seems adapted for a sessile, community lifestyle; it is competent to uptake DNA, produces much capsular polysaccharide, has a high level of c-di-GMP, and strongly expresses one type six secretion system. Expressing the entire surface sensing regulon and numerous methyl accepting chemotaxis proteins, the quorum-disrupted cell type seems prepared for a mobile lifestyle. It is also cytotoxic to host cells in co-culture and expresses distinct type six as well as type three secretion systems. Thus, the scope and nature of the genes in the OpaR regulon provide many clues to the distinguishing traits of this Vibrio species as well as to the quite divergent survival strategies of the quorum ON/OFF phase variants The gene expression profiles of different strains of Vibrio parahaemolyticus cells grown on rich medium and compared using Affymetrix custom microarrays.
Project description:The quorum regulatory cascade is poorly characterized in Vibrio parahaemolyticus, in part because swarming and pathogenicity - the hallmark traits of the organism - are repressed by this scheme of gene control. As a consequence, many isolates appear silenced for quorum sensing via phase variation. In these studies, we examine a swarm proficient, virulent strain and find an altered function allele of the central quorum regulator luxO. We use this allele, which produces a constitutively active LuxO, to probe the upstream elements of the pathway and demonstrate their functionality for the first time. We find that the state of luxO affects expression of three small regulatory RNAS (Qrrs) and the activity of a translational fusion in opaR, the central output regulator. We use microarray profiling to determine the OpaR regulon, which was found to encompass ~5.2% of the genome. The quorum sensing proficient strain seems adapted for a sessile, community lifestyle; it is competent to uptake DNA, produces much capsular polysaccharide, has a high level of c-di-GMP, and strongly expresses one type six secretion system. Expressing the entire surface sensing regulon and numerous methyl accepting chemotaxis proteins, the quorum-disrupted cell type seems prepared for a mobile lifestyle. It is also cytotoxic to host cells in co-culture and expresses distinct type six as well as type three secretion systems. Thus, the scope and nature of the genes in the OpaR regulon provide many clues to the distinguishing traits of this Vibrio species as well as to the quite divergent survival strategies of the quorum ON/OFF phase variants
Project description:Acute hepatopancreatic necrosis disease (AHPND) is a shrimp farming disease, caused by a pathogenic Vibrio parahaemolyticus carrying a plasmid encoding Vp_PirAB-like toxin (VpAHPND). Whiteleg shrimp, Litopenaeus vannamei were fed food pellets containing formalin-killed VpAHPND (FKC-VpAHPND) to select for toxin resistance. To identify genes associated with Vp_PirAB-like toxin resistance, total RNA was sequenced to identify differentially expressed genes (DEGs) in the stomach and hepatopancreas among surviving shrimp (sur-FKC), AHPND-infected shrimp (Vp-inf) and normal shrimp (control). From a total of 79,591 genes, 194 and 224 DEGs were identified in the stomach and hepatopancreas transcriptomes, respectfully. The expressions of DEGs were validated by qPCR of ten genes. Only one gene, a gene homologous to L vannamei anti-lipopolysaccharide factor AV-R isoform (LvALF AV-R), was expressed significantly more strongly in sur-FKC than in the other groups. The association of LvALF AV-R expression and toxin resistance was affirmed from the surviving shrimp in a second-trial of FKC-VpAHPND feeding. These results suggest that LvALF AV-R may be involved in shrimp defense mechanisms against Vp_PirAB-like toxin virulence.