Search results for "Virulence"

Exopolysaccharides favor the survival of Erwinia amylovora under copper stress through different strategies.

2010

Erwinia amylovora causes fire blight, a destructive disease of rosaceous plants very difficult to control. We demonstrated that copper, employed to control plant diseases, induces the "viable-but-nonculturable" (VBNC) state in E. amylovora. Moreover, it was previously reported that copper increases production of its main exopolysaccharide (EPS), amylovoran. In this work, the copper-complexing ability of amylovoran and levan, other major EPS of E. amylovora, was demonstrated. Following this, EPS-deficient mutants were used to determine the role of these EPSs in survival of this bacterium in AB mineral medium with copper, compared to their wild type strain and AB without copper. Tot…

Icosahedral dsDNA Bacterial Viruses with an Internal Membrane

2008

The icosahedral double-stranded DNA bacteriophages containing an internal membrane belong to two families, the Tectiviridae and the Corticoviridae. Members of the Tectiviridae have a linear dsDNA genome (e.g., PRD1) and those of the Corticoviridae have a circular genome (the only example being PM2). The DNA is covered by a membrane which is in turn covered by a protein capsid. The infection cycle begins when spikes on the capsid recognize the host cell receptor and the virus starts the delivery of the genome into the cell cytoplasm. The replication of the virus genome occurs in the cytoplasm. The members of the Tectiviridae may be virulent or temperate; PM2 is virulent. Virulent bacteriopha…

Impact of biotic and abiotic factors on bacterial virulence

2013

Microorganisms and Biotic Interactions

2014

SPE IPM; Most ecosystems are populated by a large number of diversified microorganisms, which interact with one another and form complex interaction networks. In addition, some of these microorganisms may colonize the surface or internal parts of plants and animals, thereby providing an additional level of interaction complexity. These microbial relations range from intraspecific to interspecific interactions, and from simple short-term interactions to intricate long-term ones. They have played a key role in the formation of plant and animal kingdoms, often resulting in coevolution; they control the size, activity level, and diversity patterns of microbial communities. Therefore, they modul…

A stoichiometric perspective on host-parasite interactions

2013

The peculiarities of genetic structure of the Blumeria graminis f. sp. hordei population in Lithuania

2014

In 2010, samples of Blumeria graminis f. sp. hordei both in sporulation and cleistothecia were collected in Lithuania from spring barley variety ‘Dina’. Eighty monopustule isolates were tested on differentials with well-known resistance genes. Frequencies of virulence genes, virulence complexity and pathotypes were detected. Virulence frequencies showed a wide range from 0 to 90%. The clear tendency of virulence increasing for Vla in cleistothecia was observed during the growing season of the pathogen. No virulences were found against resistances, which were present in the line SI1, as well as no matching virulence was found for the resistance gene mlo in Lithuania in 2010. Wide diversity o…

Evidence that water transmits Vibrio vulnificus biotype 2 infections to eels

1995

Vibrio vulnificus biotype 2 is classically considered an obligate eel pathogen. However, it has recently been associated with one human septicemic case. In this paper, the opportunistic behavior of this pathogen is discussed. The bacterium can survive alone in brackish water or attached to eel surfaces for at least 14 days. It is able to spread through water and infect healthy eels by using skin as a portal of entry. These results suggest that water and infected eels may act as reservoirs of infection. A capsule seems to be essential for waterborne infectivity, which would explain why cells recovered from naturally diseased eels give rise to pure cultures of opaque colonies. The spread of t…

A common virulence plasmid in biotype 2 Vibrio vulnificus and its dissemination aided by a conjugal plasmid.

2007

ABSTRACT Strains of Vibrio vulnificus , a marine bacterial species pathogenic for humans and eels, are divided into three biotypes, and those virulent for eels are classified as biotype 2. All biotype 2 strains possess one or more plasmids, which have been shown to harbor the biotype 2-specific DNA sequences. In this study we determined the DNA sequences of three biotype 2 plasmids: pR99 (68.4 kbp) in strain CECT4999 and pC4602-1 (56.6 kb) and pC4602-2 (66.9 kb) in strain CECT4602. Plasmid pC4602-2 showed 92% sequence identity with pR99. Curing of pR99 from strain CECT4999 resulted in loss of resistance to eel serum and virulence for eels but had no effect on the virulence for mice, an anim…

Phenotypic characterization and adhesive properties of vaginal Candida spp. strains provided by the CHU Farhat Hached (Sousse, Tunisia).

2015

Abstract Background Vulvovaginal candidiasis is a common infection among women worldwide, being Candida albicans the most commonly isolated species. Therefore, controlling this opportunistic yeast is one of the key factors for reducing nosocomial infection. Aims We investigated several virulence properties of 28 vaginal strains of Candida isolated from Tunisian women suffering from vulvovaginitis. We also analyzed the virulence properties of a clinical Candida krusei strain and five Candida reference strains. Methods Candida strains were subjected to microscopic analysis and culture in Candida ID2 chromogenic medium. The adhesive properties of these strains were estimated by the microtiter …

Susceptibility of Nile tilapia (Oreochromis niloticus) to vibriosis due to Vibrio vulnificus biotype 2 (serovar E)

2002

The present study documents the susceptibility of Nile tilapia to the experimental vibriosis caused by Vibrio vulnificus biotype 2 (serovar E) using a reference strain (Spanish Collection of Type Cultures, CECT 4604) selected for its high degree of virulence for eels. The biotype 1 of this species is one of the usual organisms involved in epizootics occurred in tilapia. After intraperitoneal injection, the selected strain developed a haemorrhagic septicaemia similar to eel vibriosis with a LD50 four log units lower than that exhibited by the type strain of the species, which belongs to the biotype 1. The results obtained in waterborne and intubation challenges indicated that water and feed …