Identification of Peptidases in Highly Pathogenic vs. Weakly Pathogenic Naegleria fowleri Amebae

• Published in: The Journal of eukaryotic microbiology 2015-01, Vol.62 (1), p.51-59
• Main Authors: Vyas, Ishan K, Jamerson, Melissa, Cabral, Guy A, Marciano‐Cabral, Francine
• Format: Article
• Language: English
• Subjects: Adolescent; Amebiasis - cerebrospinal fluid; Amebiasis - parasitology; Animals; Axenic Culture; Azocasein; Cell Fractionation; Cell Membrane - chemistry; Cell Membrane - drug effects; Cell Membrane - enzymology; Cell Movement - drug effects; central nervous system; Central Nervous System Protozoal Infections - cerebrospinal fluid; Central Nervous System Protozoal Infections - parasitology; Collagen; Culture Media, Conditioned - chemistry; Culture Media, Conditioned - metabolism; cysteine; cysteine peptidase; Cysteine Proteases - chemistry; Cysteine Proteases - isolation & purification; Cysteine Proteinase Inhibitors - pharmacology; Drug Combinations; extracellular matrix; Female; Humans; Laminin; Leucine - analogs & derivatives; Leucine - pharmacology; meningoencephalitis; Mice; Naegleria fowleri; Naegleria fowleri - drug effects; Naegleria fowleri - enzymology; Naegleria fowleri - isolation & purification; Naegleria fowleri - pathogenicity; peptidases; Proteoglycans; Protozoan Proteins - antagonists & inhibitors; Protozoan Proteins - chemistry; Protozoan Proteins - isolation & purification; zymography
• ISSN: 1066-5234; 1550-7408
• DOI: 10.1111/jeu.12152

Naegleria fowleri, a free‐living ameba, is the causative agent of Primary Amebic Meningoencephalitis. Highly pathogenic mouse‐passaged amebae (Mp) and weakly pathogenic axenically grown (Ax) N. fowleri were examined for peptidase activity. Zymography and azocasein peptidase activity assays demonstrated that Mp and Ax N. fowleri exhibited a similar peptidase pattern. Prominent for whole cell lysates, membranes and conditioned medium (CM) from Mp and Ax amebae was the presence of an activity band of approximately 58 kDa that was sensitive to E64, a cysteine peptidase inhibitor. However, axenically grown N. fowleri demonstrated a high level of this peptidase activity in membrane preparations. The inhibitor E64 also reduced peptidase activity in ameba‐CM consistent with the presence of secreted cysteine peptidases. Exposure of Mp amebae to E64 reduced their migration through matrigel that was used as an extracellular matrix, suggesting a role for cysteine peptidases in invasion of the central nervous system (CNS). The collective results suggest that the profile of peptidases is not a discriminative marker for distinguishing Mp from Ax N. fowleri. However, the presence of a prominent level of activity for cysteine peptidases in N. fowleri membranes and CM, suggests that these enzymes may serve to facilitate passage of the amebae into the CNS.