Antimicrobial Activity and Action Mechanisms of Arg-Rich Short Analog Peptides Designed from the C-Terminal Loop Region of American Oyster Defensin (AOD).

American oyster defensin (AOD) was previously purified from acidified gill extract of the American oyster, . AOD is composed of 38 amino acids with three disulfide bonds and exhibits strong antimicrobial activity against Gram-positive bacteria as well as significant activity against Gram-negative bacteria. Here, to develop promising peptides into antibiotic candidates, we designed five arginine-rich analogs (A0, A1, A2, A3, and A4), predicted their loop and extended strand/random structures-including nine amino acids and a disulfide bond derived from the C-terminus of AOD-and described their antimicrobial and cytotoxic effects, as well as their modes of action.

Male-Specific and Somatic Coliphage Profiles from Major Aquaculture Areas in Republic of Korea.

Human and animal feces are important sources of various types of microbial contamination in water. Especially, enteric viruses, the major agents of waterborne infection, can attain long-term survival in water environments due to their strong resistance to various environmental factors including pH, salinity, and temperature. Coliphages are promising viral indicators for fecal contamination in water environments.

Antimicrobial effect of the 60S ribosomal protein L29 (cgRPL29), purified from the gill of pacific oyster, Crassostrea gigas.

We purified an ∼6.4-kDa antimicrobial peptide from an acidified gill extract of the Pacific oyster, Crassostrea gigas, by cation-exchange and C reversed-phase high performance liquid chromatography (HPLC). The identified peptide was composed of 54 amino acids and had a molecular weight of 6484.

Occurrence of novel GII.17 and GII.21 norovirus variants in the coastal environment of South Korea in 2015.

Human norovirus (HNoV), a positive-sense RNA virus, is the main causative agent of acute viral gastroenteritis. Multiple pandemic variants of the genogroup II genotype 4 (GII.4) of NoV have attracted great attention from researchers worldwide.

Distribution of Human Norovirus in the Coastal Waters of South Korea.

The presence of human norovirus in the aquatic environment can cause outbreaks related to recreational activities and the consumption of norovirus-contaminated clams. In this study, we investigated the prevalence of norovirus genogroups I (GI) and II (GII) in the coastal aquatic environment in South Korea (March 2014 to February 2015). A total of 504 water samples were collected periodically from four coastal areas (total sites = 63), of which 44 sites were in estuaries (clam fisheries) and 19 were in inflow streams.

Presence of genes for type III secretion system 2 in Vibrio mimicus strains.

Background: Vibrios, which include more than 100 species, are ubiquitous in marine and estuarine environments, and several of them e.g. Vibrio cholerae, V.

Bile acid-induced virulence gene expression of Vibrio parahaemolyticus reveals a novel therapeutic potential for bile acid sequestrants.

Vibrio parahaemolyticus, a bacterial pathogen, causes human gastroenteritis. A type III secretion system (T3SS2) encoded in pathogenicity island (Vp-PAI) is the main contributor to enterotoxicity and expression of Vp-PAI encoded genes is regulated by two transcriptional regulators, VtrA and VtrB. However, a host-derived inducer for the Vp-PAI genes has not been identified.

Transcription of Vibrio parahaemolyticus T3SS1 genes is regulated by a dual regulation system consisting of the ExsACDE regulatory cascade and H-NS.

Vibrio parahaemolyticus, one of the human pathogenic vibrios, causes gastroenteritis, wound infections and septicemia. Genomic sequencing of this organism revealed that it has two distinct type III secretion systems (T3SS1 and T3SS2). T3SS1 plays a significant role in lethal activity in a murine infection model.

Two regulators of Vibrio parahaemolyticus play important roles in enterotoxicity by controlling the expression of genes in the Vp-PAI region.

Vibrio parahaemolyticus is an important pathogen causing food-borne disease worldwide. An 80-kb pathogenicity island (Vp-PAI), which contains two tdh (thermostable direct hemolysin) genes and a set of genes for the type III secretion system (T3SS2), is closely related to the pathogenicity of this bacterium. However, the regulatory mechanisms of Vp-PAI's gene expression are poorly understood.

Temperature-dependency urease activity in Vibrio parahaemolyticus is related to transcriptional activator UreR.

Vibrio parahaemolyticus possessing urease-positive property is relatively rare, but such strains consistently exhibit the TDH-related hemolysin (TRH) gene. In this study, we examined the effects of incubation temperature on urease activity expression, using the TH3996 and AQ4673 strains where the enzyme activity is known to be temperature-dependent and -independent, respectively. In the TH3996 strain, beta-galactosidase activity was 4.

Identification and characterization of a novel type III secretion system in trh-positive Vibrio parahaemolyticus strain TH3996 reveal genetic lineage and diversity of pathogenic machinery beyond the species level.

Vibrio parahaemolyticus is a bacterial pathogen causative of food-borne gastroenteritis. Whole-genome sequencing of V. parahaemolyticus strain RIMD2210633, which exhibits Kanagawa phenomenon (KP), revealed the presence of two sets of the genes for the type III secretion system (T3SS) on chromosomes 1 and 2, T3SS1 and T3SS2, respectively.

Identification of two translocon proteins of Vibrio parahaemolyticus type III secretion system 2.

The type III secretion system (T3SS) translocon complex is composed of several associated proteins, which form a translocation channel through the host cell plasma membrane. These proteins are key molecules that are involved in the pathogenicity of many T3SS-positive bacteria, because they are necessary to deliver effector proteins into host cells. A T3SS designated T3SS2 of Vibrio parahaemolyticus is thought to be related to the enterotoxicity of this bacterium in humans, but the effector translocation mechanism of T3SS2 is unclear because there is only one gene (the VPA1362 gene) in the T3SS2 region that is homologous to other translocon protein genes.

Translocation of VP1686 upregulates RhoB and accelerates phagocytic activity of macrophage through actin remodeling.

Here, we report that Vibrio parahaemolyticus induces a rapid remodeling of macrophage actin and activates RhoB GTPase. Mutational analysis revealed that the effects depend on type III secretion system 1 regulated translocation of a V. parahaemolyticus effector protein, VP1686, into the macrophages.

Precise region and the character of the pathogenicity island in clinical Vibrio parahaemolyticus strains.

In this study, we determined the borders of the pathogenicity island in V. parahaemolyticus RIMD2210633 (Vp-PAI). Vp-PAI has features in common with Tn7 and other related elements at both terminal ends.

Identification and characterization of VopT, a novel ADP-ribosyltransferase effector protein secreted via the Vibrio parahaemolyticus type III secretion system 2.

Vibrio parahaemolyticus strain RIMD2210633 has two sets of genes encoding two separate type III secretion systems (T3SSs), called T3SS1 and T3SS2. T3SS2 has a role in enterotoxicity and is present only in Kanagawa phenomenon-positive strains, which are pathogenic to humans. Accordingly, T3SS2 is considered to be closely related to V.

Two type IV pili of Vibrio parahaemolyticus play different roles in biofilm formation.

Vibrio parahaemolyticus RIMD2210633 has two sets of type IV-A pilus genes. One set is similar to that found in other Gram-negative bacteria, such as Pseudomonas aeruginosa, Vibrio cholerae (chitin-regulated pilus; ChiRP), and Vibrio vulnificus. The other is homologous to the genes for the mannose-sensitive hemagglutinin (MSHA) pilus.

VP1686, a Vibrio type III secretion protein, induces toll-like receptor-independent apoptosis in macrophage through NF-kappaB inhibition.

Vibrio parahaemolyticus, causative agent of human gastrointestinal diseases, possesses several virulent machineries including thermostable direct hemolysin and type III secretion systems (TTSS1 and -2). In this report, we establish that TTSS1-dependent secretion and translocation of a V. parahaemolyticus effector protein VP1686 into the cytosol induces DNA fragmentation in macrophages.

Identification of proteins secreted via Vibrio parahaemolyticus type III secretion system 1.

Vibrio parahaemolyticus, a gram-negative marine bacterium, is an important pathogen causing food-borne gastroenteritis or septicemia. Recent genome sequencing of the RIMD2210633 strain (a Kanagawa phenomenon-positive clinical isolate of serotype O3:K6) revealed that the strain has two sets of gene clusters that encode the type III secretion system (TTSS) apparatus. The first cluster, TTSS1, is located on the large chromosome, and the second, TTSS2, is on the small chromosome.

Escherichia coli verotoxin 1 mediates apoptosis in human HCT116 colon cancer cells by inducing overexpression of the GADD family of genes and S phase arrest.

The Escherichia coli verotoxin 1 (VT1) inhibits protein synthesis, cell proliferation, and damages endothelial cell in the hemolytic uremic syndrome. VT1 can specifically bind and act on endothelial cells as well as on many tumor cells because these cells express its high affinity receptor, globotriaosylceramide. This indicates that VT1 may have both antiangiogenic and antineoplastic activities.

Importance of Providencia species as a major cause of travellers' diarrhoea.

In this study the importance of Providencia species as a cause of travellers' diarrhoea was examined using a selective medium developed by the authors. Providencia species could easily be distinguished from other enteric pathogens by the colour of the colonies obtained. Nine strains of Providencia alcalifaciens, nine of Providencia rettgeri and five of Providencia stuartii were isolated from 130 specimens, representing a surprisingly high incidence of infection compared with other pathogens isolated on SS agar and TCBS agar.

vpaH, a gene encoding a novel histone-like nucleoid structure-like protein that was possibly horizontally acquired, regulates the biogenesis of lateral flagella in trh-positive Vibrio parahaemolyticus TH3996.

A histone-like nucleoid structure (H-NS) is a major component of the bacterial nucleoid and plays a crucial role in the global gene regulation of enteric bacteria. Here, we cloned and characterized the gene for the H-NS-like protein VpaH in Vibrio parahaemolyticus. vpaH encodes a protein of 134 amino acids that shows approximately 55%, 54%, and 41% identities with VicH in Vibrio cholerae, H-NS in V.

Microarray analysis identifies apoptosis regulatory gene expression in HCT116 cells infected with thermostable direct hemolysin-deletion mutant of Vibrio parahaemolyticus.

The thermostable direct hemolysin (TDH) is considered as a major virulence factor of Vibrio parahaemolyticus. We observed this potential in several human cancer cell lines by using the TDH-producing wild-type (RIMD2210633) as well as tdh-deletion mutant of V. parahaemolyticus and found that the deletion of tdh did not affect cytotoxicity to any of the cell lines tested.

Functional characterization of two type III secretion systems of Vibrio parahaemolyticus.

Vibrio parahaemolyticus, a gram-negative marine bacterium, is a worldwide cause of food-borne gastroenteritis. Recent genome sequencing of the clinical V. parahaemolyticus strain RIMD2210633 identified two sets of genes for the type III secretion system (TTSS), TTSS1 and TTSS2.

Cytotoxicity and enterotoxicity of the thermostable direct hemolysin-deletion mutants of Vibrio parahaemolyticus.

The thermostable direct hemolysin (TDH) has been proposed to be a major virulence factor of Vibrio parahaemolyticus. We have recently completed the genome sequence of a TDH-producing V. parahaemolyticus strain, RIMD2210633.