A Review of Clinical Trials Involving Genetically Modified Bacteria, Bacteriophages and Their Associated Risk Assessments.

Introduction: Discussion of gene-modified investigational products (IPs) in clinical trials has largely focused on nucleic acid-based vectors, viral vectors, and gene-modified cellular products involving mammalian cells. Use of bacteria and bacteriophages as IPs is resurgent, and discussion of the risks associated with genetic modification of these organisms has become pertinent to the biosafety community.

Methods: This review article summarizes the United States Food and Drug Administration classification for IPs comprising bacteria or bacteriophages and provides an overview of clinical trials conducted to date involving genetically modified bacteria.

Interspecies Expression of an EF-HAND CALCIUM-BINDING PROTEIN in Leads to Reduced Virulence and Decreased Immune Evasion in Tomato Plants.

Many phytopathogenic bacteria require a type III secretion system (TTSS) to activate effector-triggered immunity (ETI). We identified a calcium-binding protein, EfhX, in the citrus pathogen subsp. that does not require a TTSS to activate reactive oxygen species (ROS) and elicit a hypersensitive reaction (HR) in tomato leaves following infection.

Biochemical and Virulence Characterization of Isolates From Clinical and Environmental Sources.

is a deadly human pathogen for which infections occur seafood consumption (foodborne) or direct contact with wounds. Virulence is not fully characterized for this organism; however, there is evidence of biochemical and genotypic correlations with virulence potential. In this study, biochemical profiles and virulence genotype, based on 16S rRNA gene () and virulence correlated gene () types, were determined for 30 clinical and 39 oyster isolates.

Corrigendum: Phylogeny of From the Analysis of the Core-Genome: Implications for Intra-Species Taxonomy.

[This corrects the article DOI: 10.3389/fmicb.2017.

Detection of Virulence Plasmid-Encoded Genes in Typhimurium and Kentucky Isolates Recovered from Commercially Processed Chicken Carcasses.

serovar Typhimurium is one of the leading causes of nontyphoidal gastroenteritis of humans in the United States. Commercially processed poultry carcasses are frequently contaminated with serovar Kentucky in the United States. The aim of the study was to detect the virulence plasmid containing the genes from isolates recovered from commercially processed chicken carcasses.

Relative Contributions of and Bacteriophage to Bacterial Cell Death under Various Environmental Conditions.

The role of protists and bacteriophages in bacterial predation in the microbial food web has been well studied. There is mounting evidence that and like organisms (BALOs) also contribute to bacterial mortality and, in some cases, more so than bacteriophages. A full understanding of the ecologic function of the microbial food web requires recognition of all major predators and the magnitude of each predator's contribution.

Phylogeny of from the Analysis of the Core-Genome: Implications for Intra-Species Taxonomy.

(Vv) is a multi-host pathogenic species currently subdivided into three biotypes (Bts). The three Bts are human-pathogens, but only Bt2 is also a fish-pathogen, an ability that is conferred by a transferable virulence-plasmid (pVvbt2). Here we present a phylogenomic analysis from the core genome of 80 Vv strains belonging to the three Bts recovered from a wide range of geographical and ecological sources.

The Opportunistic Pathogen Produces Outer Membrane Vesicles in a Spatially Distinct Manner Related to Capsular Polysaccharide.

, a bacterial species that inhabits brackish waters, is an opportunistic pathogen of humans. infections can cause acute gastroenteritis, invasive septicemia, tissue necrosis, and potentially death. Virulence factors associated with include the capsular polysaccharide (CPS), lipopolysaccharide, flagellum, pili, and outer membrane vesicles (OMVs).

Hepcidin-induced hypoferremia is a critical host defense mechanism against the siderophilic bacterium Vibrio vulnificus.

Hereditary hemochromatosis, an iron overload disease caused by a deficiency in the iron-regulatory hormone hepcidin, is associated with lethal infections by siderophilic bacteria. To elucidate the mechanisms of this susceptibility, we infected wild-type and hepcidin-deficient mice with the siderophilic bacterium Vibrio vulnificus and found that hepcidin deficiency results in increased bacteremia and decreased survival of infected mice, which can be partially ameliorated by dietary iron depletion. Additionally, timely administration of hepcidin agonists to hepcidin-deficient mice induces hypoferremia that decreases bacterial loads and rescues these mice from death, regardless of initial iron levels.

Genotype is correlated with but does not predict virulence of Vibrio vulnificus biotype 1 in subcutaneously inoculated, iron dextran-treated mice.

Vibrio vulnificus is the leading cause of reported deaths from infections related to consumption of seafood in the United States. Affected predisposed individuals frequently die rapidly from sepsis. Otherwise healthy people can experience severe wound infection, which can lead to sepsis and death.

SOLiD sequencing of four Vibrio vulnificus genomes enables comparative genomic analysis and identification of candidate clade-specific virulence genes.

Background: Vibrio vulnificus is the leading cause of reported death from consumption of seafood in the United States. Despite several decades of research on molecular pathogenesis, much remains to be learned about the mechanisms of virulence of this opportunistic bacterial pathogen. The two complete and annotated genomic DNA sequences of V.

Role of GacA in virulence of Vibrio vulnificus.

The GacS/GacA two-component signal transduction system regulates virulence, biofilm formation and symbiosis in Vibrio species. The present study investigated this regulatory pathway in Vibrio vulnificus, a human pathogen that causes life-threatening disease associated with the consumption of raw oysters and wound infections. Small non-coding RNAs (csrB1, csrB2, csrB3 and csrC) commonly regulated by the GacS/GacA pathway were decreased (P<0.

Genetic characterization of Vibrio vulnificus strains from tilapia aquaculture in Bangladesh.

Outbreaks of Vibrio vulnificus wound infections in Israel were previously attributed to tilapia aquaculture. In this study, V. vulnificus was frequently isolated from coastal but not freshwater aquaculture in Bangladesh.

Phase variation, capsular polysaccharide, pilus and flagella contribute to uptake of Vibrio vulnificus by the Eastern oyster (Crassostrea virginica).

Vibrio vulnificus infections are associated with raw oyster consumption, and disease reservoirs are determined by the ability of this bacterium to infect and persist in oysters. Surface structures, such as capsular polysaccharide (CPS), pili and flagella, function as virulence factors in mouse infection models. Furthermore, virulence is related to phase variation in colony morphology, which reflects CPS expression and includes opaque (encapsulated, virulent), translucent (reduced encapsulation, avirulent) and rugose (wrinkled, biofilm-enhanced) colony types.

Roles of RseB, sigmaE, and DegP in virulence and phase variation of colony morphotype of Vibrio vulnificus.

Vibrio vulnificus is an estuarine bacterium capable of causing serious and often fatal wound infections and primary septicemia. We used alkaline phosphatase insertion mutagenesis to identify genes necessary for the virulence of this pathogen. One mutant had an in-frame fusion of 'phoA to the gene encoding RseB, a periplasmic negative regulator of the alternative sigma factor sigma(E).

Regulation of fatty acid metabolism by FadR is essential for Vibrio vulnificus to cause infection of mice.

The opportunistic bacterial pathogen Vibrio vulnificus causes severe wound infection and fatal septicemia. We used alkaline phosphatase insertion mutagenesis in a clinical isolate of V. vulnificus to find genes necessary for virulence, and we identified fadR, which encodes a regulator of fatty acid metabolism.

Use of a marker plasmid to examine differential rates of growth and death between clinical and environmental strains of Vibrio vulnificus in experimentally infected mice.

Vibrio vulnificus is Gram-negative bacterium that contaminates oysters, causing highly lethal sepsis after consumption of raw oysters and wound infection. We previously described two sets of V. vulnificus strains with different levels of virulence in subcutaneously inoculated iron dextran-treated mice.

Molecular Pathogenesis of Vibrio vulnificus.

Vibrio vulnificus is an opportunistic pathogen of humans that has the capability of causing rare, yet devastating disease. The bacteria are naturally present in estuarine environments and frequently contaminate seafoods. Within days of consuming uncooked, contaminated seafood, predisposed individuals can succumb to sepsis.

CapG(-/-) mice have specific host defense defects that render them more susceptible than CapG(+/+) mice to Listeria monocytogenes infection but not to Salmonella enterica serovar Typhimurium infection.

Loss of the actin filament capping protein CapG has no apparent effect on the phenotype of mice maintained under sterile conditions; however, bone marrow-derived macrophages from CapG(-/-) mice exhibited distinct motility defects. We examined the ability of CapG(-/-) mice to clear two intracellular bacteria, Listeria monocytogenes and Salmonella enterica serovar Typhimurium. The 50% lethal dose of Listeria was 10-fold lower for CapG(-/-) mice than for CapG(+/+) mice (6 x 10(3) CFU for CapG(-/-) mice and 6 x 10(4) CFU for CapG(+/+) mice), while no difference was observed for Salmonella: The numbers of Listeria cells in the spleens and livers were significantly higher in CapG(-/-) mice than in CapG(+/+) mice at days 5 to 9, while the bacterial counts were identical on day 5 for Salmonella-infected mice.

Analysis of Vibrio vulnificus from market oysters and septicemia cases for virulence markers.

Representative encapsulated strains of Vibrio vulnificus from market oysters and oyster-associated primary septicemia cases (25 isolates each) were tested in a blinded fashion for potential virulence markers that may distinguish strains from these two sources. These isolates were analyzed for plasmid content, for the presence of a 460-bp amplicon by randomly amplified polymorphic DNA PCR, and for virulence in subcutaneously (s.c.

Phage therapy of local and systemic disease caused by Vibrio vulnificus in iron-dextran-treated mice.

Vibrio vulnificus is a gram-negative bacterium that contaminates filter-feeding shellfish such as oysters. After ingestion of contaminated oysters, predisposed people may experience highly lethal septicemia. Contamination of wounds with the bacteria can result in devastating necrotizing fasciitis, which can progress to septicemia.

Bacteriophages: potential treatment for bacterial infections.

Bacteriophages (phages) are viruses of bacteria that can kill and lyse the bacteria they infect. After their discovery early in the 20th century, phages were widely used to treat various bacterial diseases in people and animals. After this enthusiastic beginning to phage therapy, problems with inappropriate use and uncontrolled studies and ultimately the development of antibacterials caused a cessation of phage therapy research in the West.