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Elevated levels of cellular and extracellular phospholipases from pathogenic Naegleria fowleri
Abstract:
Phospholipase A, sphingomyelinase and lysophospholipase activities were examined in cell homogenates and cell-free culture media of virulent and virulent-attenuated Naegleria fowleri and nonpathogenic Naegleria gruberi. Homogenates of virulent N. fowleri contained from 3 to 250 times the lipolytic activity of virulent-attenuated and non-pathogenic Naegleria spp. Similarly, the cell-free media of virulent N. fowleri cultures contained large quantities of phospholipase A, lysophospholipase and sphingomyelinase while comparable activities in the cell-free media of virulent-attenuated and nonpathogenic Naegleria spp. were only slightly, if at all, detectable. Lipolytic enzymes accumulated in the media of virulent N. fowleri cultures at various stages during growth but not in virulent-attenuated and nonpathogenic Naegleria cultures. In general, phospholipase A and sphingomyelinase accumulated during the log phase of growth while lysophospholipase appeared only in the late stationary phase. We conclude that pathogenic Naegleria contain potent lipolytic enzymes that are released selectively into the media during growth. These enzymes could contribute to the pathogenesis of Naegleria-induced primary amoebic meningoencephalitis.
Insights
Pathogenic Naegleria fowleri releases potent lipolytic enzymes, including phospholipase A and sphingomyelinase, into its environment. These enzymes are linked to the severe brain infection primary amoebic meningoencephalitis.
Area of Science:
- Microbiology
- Enzymology
- Parasitology
Background:
- Naegleria fowleri is a pathogenic amoeba causing primary amoebic meningoencephalitis.
- Understanding the enzymatic activities of Naegleria species is crucial for elucidating pathogenic mechanisms.
Purpose of the Study:
- To investigate and compare the phospholipase A, sphingomyelinase, and lysophospholipase activities in virulent and attenuated Naegleria fowleri and nonpathogenic Naegleria gruberi.
- To determine if these lipolytic enzymes are secreted and their potential role in pathogenesis.
Main Methods:
- Enzyme activity assays were performed on cell homogenates and cell-free culture media.
- Comparison of lipolytic activities across different Naegleria species and virulence states.
- Analysis of enzyme accumulation during different growth phases.
Main Results:
- Virulent N. fowleri exhibited significantly higher lipolytic activity (3-250 times) compared to attenuated and nonpathogenic strains.
- High levels of phospholipase A, lysophospholipase, and sphingomyelinase were detected in the cell-free media of virulent N. fowleri.
- These enzymes accumulated in the media of virulent N. fowleri during growth, with specific patterns for each enzyme type.
Conclusions:
- Pathogenic Naegleria species possess potent lipolytic enzymes that are selectively released during growth.
- These secreted enzymes are likely contributors to the pathogenesis of primary amoebic meningoencephalitis.