Listeriolysin O (LLO) is an essential virulence factor for the gram-positive bacterium Listeria monocytogenes. Our goal was to determine if altering the topology of LLO would alter the virulence and toxicity of L. monocytogenes in vivo. A recombinant strain was generated that expressed a surface-associated LLO (sLLO) variant secreted at 40-fold-lower levels than the wild type. In culture, the s...

Listeria monocytogenes is a gram-positive, foodborne bacterium responsible for disease in humans and animals. Listeriolysin O (LLO) is a required virulence factor for the pathogenic effects of L. monocytogenes. Bioinformatics revealed conserved putative epitopes of LLO that could be used to develop monoclonal antibodies against LLO. Continuous and discontinuous epitopes were located by using fo...

Oleanolic acid and ursolic acid are pentacyclic triterpenoids isolated from a variety of medicinal plants, which have antibacterial activity. Listeria monocytogenes is a Gram-positive facultative pathogen, being the causative agent of listeriosis. The present study was carried out to evaluate the in vitro effect of sub-inhibitory concentrations of both triterpene acids on the pathogenicity dete...

The pore-forming toxin listeriolysin O (LLO) is a major virulence factor implicated in escape of Listeria monocytogenes from phagocytic vacuoles. Here we describe the pH-dependence of vacuolar perforation by LLO, using the membrane-impermeant fluorophore 8-hydroxypyrene-1,3,6-trisulfonic acid (HPTS) to monitor the pH and integrity of vacuoles in mouse bone marrow-derived macrophages. Perforatio...

Listeria monocytogenes, an emerging foodborne pathogen, can cause in the population at risk severe infections that are associated with high case fatality rates. A total of 93 L. monocytogenes strains isolated from different patients in Switzerland from July 2011 to September 2013 were further characterized. Septicemia was reported for 74.2% of the patients, meningitis for 10.8%, and abortion fo...

Human E-cadherin and listeriolysin O (LLO) are involved in invasion of Listeria monocytogenes into human liver parenchymal cells (LPC). Yet, it remains to be determined whether murine E-cadherin and LLO participate in invasion of L. monocytogenes into murine LPC. In the present study, involvement of murine E-cadherin and LLO in invasion of L. monocytogenes into murine LPC was investigated. Muri...

Listeria monocytogenes is a facultative, intracellular, gram-positive bacterium that causes listeriosis in immunocompromised patients, causing death in 20%-30% of infected individuals [1,2]. In severe cases, this pathogen has been shown to enter the central nervous system (CNS). Usually, Listeria monocytogenes is ingested from contaminated food, particularly seafood, soft cheeses, and meat, bei...

Pore formation of cellular membranes is an ancient mechanism of bacterial pathogenesis that allows efficient damaging of target cells. Several mechanisms have been described, however, relatively little is known about the assembly and properties of pores. Listeriolysin O (LLO) is a pH-regulated cholesterol-dependent cytolysin from the intracellular pathogen Listeria monocytogenes, which forms tr...

For rapid and inexpensive detection of polymerase chain reaction (PCR) amplicons, a novel microsphere agglutination assay has been developed. PCR is carried out using biotinylated forward and reverse primers, and the amplified DNA fragments are able to agglutinate streptavidin-coated microspheres (5.7 microm in diameter). Purification of PCR amplicons is unnecessary when initial primer concentr...

Studies were undertaken to compare the detection of anti-listeriolysin O antibodies (ALLO) and isolation of Listeria monocytogenes from meat and milk samples of sheep and goats. Out of 201 samples (87 of milk and 114 of meat) tested, 17.64% yielded Listeria species isolates. L. monocytogenes was isolated from 6.66 and 1.56% of meat (60) and (64) milk samples of goats, respectively, and 7.4% of ...