Dataset Information

Mitochondrial genome diversity of Balamuthia mandrillaris revealed by a fatal case of granulomatous amoebic encephalitis.

ABSTRACT:

Introduction

Balamuthia (B.) mandrillaris is a free-living amoeba that can cause rare yet fatal granulomatous amoebic encephalitis (GAE). However, efficacious treatment for GAE is currently unavailable, especially when genomic studies on B. mandrillaris are limited.

Methods

In this study, B. mandrillaris strain KM-20 was isolated from the brain tissue of a GAE patient, and its mitochondrial genome was de novo assembled using high-coverage Nanopore long reads and Illumina short reads.

Results and discussion

Phylogenetic and comparative analyses revealed a range of diversification in the mitochondrial genome of KM-20 and nine other B. mandrillaris strains. According to the mitochondrial genome alignment, one of the most variable regions was observed in the ribosomal protein S3 (rps3), which was caused by an array of novel protein tandem repeats. The repeating units in the rps3 protein tandem region present significant copy number variations (CNVs) among B. mandrillaris strains and suggest KM-20 as the most divergent strain for its highly variable sequence and highest copy number in rps3. Moreover, mitochondrial heteroplasmy was observed in strain V039, and two genotypes of rps3 are caused by the CNVs in the tandem repeats. Taken together, the copy number and sequence variations of the protein tandem repeats enable rps3 to be a perfect target for clinical genotyping assay for B. mandrillaris. The mitochondrial genome diversity of B. mandrillaris paves the way to investigate the phylogeny and diversification of pathogenic amoebae.

SUBMITTER: Law CT

PROVIDER: S-EPMC10196457 | biostudies-literature | 2023

REPOSITORIES: biostudies-literature

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Publications

Mitochondrial genome diversity of <i>Balamuthia mandrillaris</i> revealed by a fatal case of granulomatous amoebic encephalitis.

Law Cherie Tsz-Yiu CT Nivesvivat Thirapa T Xiong Qing Q Kulkeaw Kasem K Shi Ling L Ruenchit Pichet P Suwanpakdee Detchvijitr D Suwanpakdee Piradee P Tongkrajang Nongnat N Sarasombath Patsharaporn T PT Tsui Stephen Kwok-Wing SK

Frontiers in microbiology 20230505

<h4>Introduction</h4><i>Balamuthia</i> (<i>B.</i>) <i>mandrillaris</i> is a free-living amoeba that can cause rare yet fatal granulomatous amoebic encephalitis (GAE). However, efficacious treatment for GAE is currently unavailable, especially when genomic studies on <i>B. mandrillaris</i> are limited.<h4>Methods</h4>In this study, <i>B. mandrillaris</i> strain KM-20 was isolated from the brain tissue of a GAE patient, and its mitochondrial genome was <i>de novo</i> assembled using high-coverage ...[more]

PMID: 37213512

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Project description:BackgroundGranulomatous amoebic encephalitis (GAE) is a rare central nervous system infection caused by the Balamuthia mandrillaris or Acanthamoeba species. Diagnosis is challenging because of the non-specific clinical presentation, cerebrospinal fluid analysis, and radiological features. There is no effective treatment for GAE to date.Case presentationA 54-year-old male was admitted to hospital after experiencing acute onset of numbness and weakness on his left limb. Due to the initial consideration of intracranial tumor, surgical removal of the right parietal lesion was performed. However, the patient had a headache accompanied by diplopia, difficulty walking and a new lesion was found in the left occipital-parietal lobe two weeks after the first operation. High-throughput next-generation sequencing (NGS) detected the presence of high copy reads of the B. mandrillaris genome sequence in the patient's blood, cerebral spinal fluid (CSF), and brain tissue. Pathological investigation of the brain tissue showed granulomatous changes and amoebic trophozoite scattered around blood vessels under high magnification. The patient was re-operated due to developing progressive confusion caused by subfalcine herniation of the left cerebral hemisphere. The lesions of the right parietal lobe were obviously decreasing in size after the first surgery, and the lesions of the left occipital lobe and the sunfalcine herniation didn't ameliorate two months after the second surgery. The patient was transferred to local hospital for continuous treatment with sulfamethoxazole and azithromycin. After five months of the second surgery, the patient showed good recovery with mild headache.ConclusionsThis is the first report of a patient with B. mandrillaris encephalitis initially confirmed by NGS and have experienced two excisions, responding favorably to the combination of surgeries and medications. Early surgical resection of intracranial lesions combined with drug treatment may offer the chance of a cure.