Acanthamoeba healyi: expressed gene profiles with enhanced virulence after mouse-brain passage

Area of Science:

• Microbiology
• Molecular Biology
• Pathogenesis

Background:

• Acanthamoeba virulence decreases with long-term in vitro cultivation.
• Virulence can be restored through serial passage in mouse brains.
• Changes in virulence-related gene expression accompany virulence recovery.

Purpose of the Study:

• To investigate Acanthamoeba virulence factors by comparing gene expression.
• To identify differences between in vitro cultivated and mouse-passaged Acanthamoeba strains.
• To understand the genetic basis of Acanthamoeba pathogenesis.

Main Methods:

• Expressed sequence tags (ESTs) were generated from two Acanthamoeba healyi cDNA libraries: long-term in vitro cultivated (OLD) and mouse-brain passaged (MBP).
• Reciprocal BLAST analysis, eukaryotic orthologous groups (KOG) assignment, and gene annotation were used for comparison.
• Sequencing and assembly of ESTs were performed to identify unique sequences.

Main Results:

• A total of 718 OLD and 833 MBP unique sequences were assembled from 938 OLD and 1033 MBP ESTs.
• KOG analysis showed a higher percentage of MBP ESTs involved in transcription, amino acid, coenzyme, and secondary metabolite transport/metabolism.
• A significantly higher percentage of unidentified MBP ESTs (57.9%) compared to OLD ESTs (28.9%) suggests limited knowledge of virulence factors.

Conclusions:

• Mouse brain passage alters Acanthamoeba gene expression, potentially related to virulence recovery.
• Specific gene categories (transcription, metabolism) are upregulated after mouse passage.
• Further characterization of genes expressed during brain passage is crucial for understanding granulomatous amoebic encephalitis pathogenesis.