The free living amoeba Naegleria fowleri is pathogenic to humans but also to other mammalians. These amoebae may invade the nasal mucosa and migrate into the brain causing cerebral hemorrhagic necrosis, a rapidly fatal infection. Knowledge of the cytolytic mechanism involved in the destruction of brain tissues by Naegleria trophozoites is limited. In other amoebic species, such as Entamoeba histolytica, we have previously reported the possible lytic role of small cytoplasmic components endowed with proteolytic activities, known as electrondense granules (EDG). Using transmission electron microscopy we now report that EDG, seldom found in long term cultured N. fowleri, are present in abundance in trophozoites recovered from experimental mice brain lesions. Numerous EDG were also observed in amoebae incubated with collagen substrates or cultured epithelial cells. SDS-PAGE assays of concentrated supernatants of these trophozoites, containing EDG, revealed proteolytic activities. These results suggest that EDG may have a clear role in the cytopathic mechanisms of this pathogenic amoeba.
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http://dx.doi.org/10.1016/j.exppara.2014.03.027 | DOI Listing |
BMC Med Genomics
January 2025
Department of Clinical Laboratory Sciences, The Faculty of Applied Medical Sciences, Taif University, Taif, Saudi Arabia.
Naegleria fowleri, the causative agent of Primary Amoebic Meningoencephalitis (PAM), is commonly found in warm freshwater environments and can enter the brain through nasal passages during activities like swimming or ablution. PAM has a high fatality rate, raising concerns about its global health impact. In Pakistan, particularly in Karachi, a significant number of cases have been reported, often with no history of recreational water exposure, but with regular ablution using tap water.
View Article and Find Full Text PDFFront Cell Infect Microbiol
January 2025
Department of Biomedical Science and Technology, School of Biological Sciences, Ramakrishna Mission Vivekananda Educational and Research Institute (RKMVERI), Kolkata, India.
Amoebae, fascinatingly diverse protists, showcase a dual nature that positions them as both friends and foes in our world. These organisms, defined by their distinctive pseudopodia, span a spectrum from harmful to helpful. On the darker side, species like pose serious health risks, causing intestinal and liver diseases, while the infamous "brain-eating" leads to fatal primary amoebic meningoencephalitis (PAM), with a daunting 97% mortality rate.
View Article and Find Full Text PDFFront Cell Infect Microbiol
December 2024
Institut Pasteur de la Guadeloupe, Les Abymes, Guadeloupe, France.
The free-living amoeba (NF) causes a rare but lethal parasitic meningoencephalitis (PAM) in humans. Currently, this disease lacks effective treatments and the specific molecular mechanisms that govern NF pathogenesis and host brain response remain unknown. To address some of these issues, we sought to explore naturally existing virulence diversity within environmental NF isolates.
View Article and Find Full Text PDFParasitol Res
December 2024
Department of Clinical Laboratory Sciences, School of Health Professions, Medical Branch, University of Texas, 301 University Blvd, Galveston, TX, 77555-0128, USA.
Naegleria fowleri is a free-living amoeba and the causative agent of Primary Amebic Meningoencephalitis (PAM), a rare yet almost always fatal disease that primarily affects children. While only 431 PAM cases have been reported worldwide, the southern states of the United States, including Texas, report the highest number of cases. Despite the high mortality of the disease, studies have identified antibodies to N.
View Article and Find Full Text PDFMicrob Pathog
December 2024
Diamond Harbour Women's University, Department of Zoology, Sarisha, West Bengal, 743368, India. Electronic address:
Naegleria fowleri, is the causative agent of Primary Amoebic Meningoencephalitis (PAM), a lethal acute brain inflammation with high mortality. The virulent and reproductively active trophozoite stage of N. fowleri migrates to central nervous system (CNS) by entering through nasal passage and causes severe neural infection, brain disease and inflammation with high mortality.
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