Biology subjects

Choi, Y.-J.

Publications and source records attributed to Choi, Y.-J..

5 recordsLinked to original sources

bioRxiv2026

Mitochondrial genomes of individual microfilariae: Undescribed Dirofilaria-like filariae from Malaysian cats and two filaria species related to Dirofilaria and Mansonella from Indonesian macaques

Three molecularly undescribed filarial species were co-detected, while screening animals for Brugia malayi, the agent of lymphatic filariasis. Single microfilariae (Mf) isolated from blood samples of crab-eating macaques (Macaca fascicularis) from Belitung, Indonesia, and from pet dogs and cats in Sabah, Malaysia, were analyzed. Among 163 macaques, 33 (20.2%) were positive for large Mf (mean length 498.9 {micro}m) similar to Dirofilaria ( Belitung I). One macaque was infected with small Mf (mean length 150.4 {micro}m) ( Belitung II), with a high density of 17,150 Mf/mL. In two cats co-infected with B. malayi, Mf of a Dirofilaria species ( Sabah) with an average length of 299.1 {micro}m were detected. Morphometric analysis of Mf showed distinct differences between these three species and other Mf described in the area. Whole genome amplification and genome sequencing of 24 individual Mf enabled phylogenetic analysis of mitochondrial genomes, and analysis of specific mitochondrial and nuclear barcode regions. The three Mf groups formed distinct clusters and did not match any currently available reference sequence. Cluster Belitung I from macaques formed a sister group to all other Dirofilaria. Cluster Belitung II included bird filariae and primate filariae of the genus Mansonella as close relatives. The cluster Sabah formed a monophyletic group with the zoonotic species D. asiatica and Dirofilaria sp. Thailand. DNA of Wolbachia endobacteria was detected in Mf of Belitung I and Sabah, but not in Belitung II. These findings highlight the limited understanding of filarial diversity in macaques and cats in Asia and underscore the need for a more comprehensive approach that combines morphological and molecular data to identify and assess the pathogenicity and zoonotic potential of these parasites. Author summaryFilarial worms are parasitic nematodes that infect humans and animals and are often transmitted by the same vector mosquito. We identified three molecularly undescribed filarial species while investigating animals as reservoirs for the agent of lymphatic filariasis, Brugia malayi on Belitung Island, Indonesia, and in Sabah, Malaysia. Blood samples were collected from Indonesian macaques and Malaysian pet cats. Out of 163 macaques, 20.2% tested positive for exceptionally large microfilariae (Mf) of an unclassified Dirofilaria-like species (Belitung I). Another filarial species ( Belitung II) with very small Mf, but with a remarkably high density of 17,150 Mf/mL was detected in one macaque. Two cats harbored medium sized Mf of a Dirofilaria species (Sabah). Genetic analysis revealed unique phylogenetic clusters that did not match any reference sequence. Dirofilaria sp. Sabah was closely related to the zoonotic D. asiatica complex, whereas Belitung I clustered as a sister group to Dirofilaria. Belitung II Mf clustered next to but not within the Mansonella spp. cluster. DNA of Wolbachia endobacteria was only detected in Mf of Belitung I and Sabah. These findings highlight the limited understanding of filarial diversity in animals and underscore the need for a comprehensive approach that combines morphological and molecular data to identify and assess the pathogenicity and zoonotic potential of these parasites.

microbiology↗

bioRxiv2024

Effect of the daily exposure of 1.7 GHz LTE electromagnetic field in early fetal brain development using a human brain organoid model of the cerebral cortex

Wireless communication technologys ubiquity means constant exposure to radiofrequency electromagnetic fields (RF-EMF). While concerns exist about RF-EMFs effects on fetal brain development, studying this in pregnant women poses ethical and safety challenges. Our study examined 1.7 GHz LTE RF-EMFs impact on early human fetal brain development using brain organoids derived from human induced pluripotent stem cells (hiPSCs). Previous research showed that 100-day-old human cerebral cortical brain organoids correspond to 19-24 weeks post-conception of fetal brain development. We exposed organoids to 1.7 GHz LTE RF-EMF at 8 W/kg specific absorption rate (SAR) for 5 hours daily up to 100 days. We monitored size, developmental morphology, and developmental stage markers using immunofluorescence microscopy and qPCR analysis. Comparing RF-EMF-exposed organoids with controls showed no significant differences in size, development, or expression of key markers: SOX2 and PAX6 (pluripotent cell markers), NEUN (mature neuronal marker), MAP2 (dendrite marker), and SYN1 (synapse marker). Results suggest that daily exposure to 1.7 GHz LTE RF-EMF at 8 W/kg SAR may not significantly affect early human fetal brain development.

developmental biology↗

bioRxiv2024

Characterization of newly isolated bacteriophages targeting carbapenem-resistant Klebsiella pneumoniae

Klebsiella pneumoniae, a Gram-negative opportunistic pathogen, is increasingly resistant to carbapenems in clinical settings. This growing problem necessitates the development of alternative antibiotics, with phage therapy being one promising option. In this study, we investigated novel phages targeting carbapenem-resistant Klebsiella pneumoniae (CRKP) and evaluated their lytic capacity against clinical isolates of CRKP. First, 23 CRKP clinical isolates were characterized using Multi-locus Sequence Typing (MLST), carbapenemase test, string test, and capsule typing. MLST classified the 23 K. pneumoniae isolates into 10 sequence types (STs), with the capsule types divided into nine known and one unknown type. From sewage samples collected from a tertiary hospital, 38 phages were isolated. Phenotypic and genotypic characterization of these phages was performed using Random Amplification of Polymorphic DNA-PCR (RAPD-PCR), transmission electron microscopy (TEM), and whole genome sequencing (WGS) analysis. Host spectrum analysis revealed that each phage selectively lysed strains sharing the same STs as their hosts, indicating ST-specific activity. These phages were subtyped based on their host spectrum and RAPD-PCR, identifying nine and five groups, respectively. Fourteen phages were selected for further analysis using TEM and WGS, revealing 13 Myoviruses and one Podovirus. Genomic analysis grouped the phages into three clusters: one closely related to Alcyoneusvirus, one to Autographiviridae, and others to Straboviridae. Our results showed that the host spectrum of K. pneumoniae-specific phages corresponds to the STs of the host strain. These 14 novel phages also hold promise as valuable resources for phage therapy against CRKP.

microbiology↗

bioRxiv2022

Optimizing CpG spatial distribution with DNA origami for Th1-polarized therapeutic vaccination

Multivalent presentation of ligands often enhances receptor activation and downstream signaling. DNA origami offers precise nanoscale spacing of ligands, a potentially useful feature for therapeutic nanoparticles. Here we introduce a "square block" DNA origami platform to explore the importance of spacing of CpG oligonucleotides, which engage Toll-like receptors and thereby act as danger signals for dendritic cells. Through in vitro cell-culture studies and in vivo tumor-treatment models, we demonstrate that square blocks induce Th1 immune polarization when CpG is spaced at 3.5 nm. We observe that this DNA origami vaccine enhances DC activation, antigen cross-presentation, CD8 T cell activation, Th1-polarized CD4 activation and NK cell activation. The vaccine also synergizes effectively with anti-PD-L1 for improved cancer immunotherapy in melanoma and lymphoma models and induces long-term T cell memory. Our results suggest that DNA origami may serve as an advanced vaccine platform for controlling adjuvant spacing and co-delivering antigens. One Sentence SummaryThis study developed a DNA origami-based cancer vaccine (DoriVac) that co-delivers antigen and CpG immune adjuvant with an optimal nanospacing for Th1 immune polarization.

synthetic biology↗

bioRxiv2018

Comprehensive analysis of human hookworm secreted proteins using a proteogenomic approach

The human hookworm Necator americanus infects more than 400 million people worldwide, contributing substantially to the poverty in these regions. Adult stage N. americanus live in the small intestine of the human host where they inject excretory/secretory (ES) products into the mucosa. ES products have been characterized at the proteome level for a number of animal hookworm species, but until now, the difficulty in obtaining sufficient live N. americanus has been an obstacle in characterizing the secretome of this important human pathogen. Herein we describe the ES proteome of N. americanus and utilize this information to conduct the first proteogenomic analysis of a parasitic helminth, significantly improving the available genome and thereby generating a robust description of the parasite secretome. The genome annotation resulted in a a revised prediction of 3,425 fewer genes than initially reported, accompanied by a significant increase in the number of exons and introns, total gene length and the percentage of the genome covered by genes. Almost 200 ES proteins were identified by LC-MS/MS with SCP/TAPS proteins, hypothetical proteins and proteases among the most abundant families. These proteins were compared to commonly used model species of human parasitic infections, including Ancylostoma caninum, Nippostrongylus brasiliensis and Heligmosomoides polygyrus. Our findings provide valuable information on important families of proteins with both known and unknown functions that could be instrumental in host-parasite interactions, including protein families that might be key for parasite survival in the onslaught of robust immune responses, as well as vaccine and drug targets.

microbiology↗