Journal of Microbiology

Reviews

Current status and perspectives on vaccine development against dengue virus infection: Jisang Park , Ju Kim , Yong-Suk Jang; J. Microbiol. 2022;60(3):247-254. Published online February 14, 2022; DOI: https://doi.org/10.1007/s12275-022-1625-y

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30 Citations

Abstract: Dengue virus (DENV) consists of four serotypes in the family Flaviviridae and is a causative agent of dengue fever, dengue hemorrhagic fever, and dengue shock syndrome. DENV is transmitted by mosquitoes, Aedes aegypti and A. albopictus, and is mainly observed in areas where vector mosquitoes live. The number of dengue cases reported by the World Health Organization increased more than 8-fold over the last two decades from 505,430 in 2000 to over 2.4 million in 2010 to 5.2 million in 2019. Although vaccine is the most effective
method
against DENV, only one commercialized vaccine exists, and it cannot be administered to children under 9 years of age. Currently, many researchers are working to resolve the various problems hindering the development of effective dengue vaccines; understanding of the viral antigen configuration would provide insight into the development of effective vaccines against DENV infection. In this review, the current status and perspectives on effective vaccine development for DENV are examined. In addition, a plausible direction for effective vaccine development against DENV is suggested.

Nanoparticle and virus-like particle vaccine approaches against SARS-CoV-2: Chulwoo Kim , Jae-Deog Kim , Sang-Uk Seo; J. Microbiol. 2022;60(3):335-346. Published online January 28, 2022; DOI: https://doi.org/10.1007/s12275-022-1608-z

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Abstract: The global spread of coronavirus disease 2019 caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has provoked an urgent need for prophylactic measures. Several innovative vaccine platforms have been introduced and billions of vaccine doses have been administered worldwide. To enable the creation of safer and more effective vaccines, additional platforms are under development. These include the use of nanoparticle (NP) and virus-like particle (VLP) technology. NP vaccines utilize self-assembling scaffold structures designed to load the entire spike protein or receptor-binding domain of SARS-CoV-2 in a trimeric configuration. In contrast, VLP vaccines are genetically modified recombinant viruses that are considered safe, as they are generally replication-defective. Furthermore, VLPs have indigenous immunogenic potential due to their microbial origin. Importantly, NP and VLP vaccines have shown stronger immunogenicity with greater protection by mimicking the physicochemical characteristics of SARS-CoV-2. The study of NPand VLP-based coronavirus vaccines will help ensure the development of rapid-response technology against SARS-CoV-2 variants and future coronavirus pandemics.

Journal Articles

Genome information of the cellulolytic soil actinobacterium Isoptericola dokdonensis DS-3 and comparative genomic analysis of the genus Isoptericola: Yurim Bae , Sujin Lee , Kitae Kim , Hyun-Kwon Lee , Soon-Kyeong Kwon , Jihyun F. Kim; J. Microbiol. 2021;59(11):1010-1018. Published online November 1, 2021; DOI: https://doi.org/10.1007/s12275-021-1452-6

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Abstract: The actinobacterial group is regarded as a reservoir of biologically active natural products and hydrolytic enzymes with the potential for biomedical and industrial applications. Here, we present the complete genome sequence of Isoptericola dokdonensis DS-3 isolated from soil in Dokdo, small islets in the East Sea of Korea. This actinomycete harbors a large number of genes encoding carbohydrate-degrading enzymes, and its activity to degrade carboxymethyl cellulose into glucose was experimentally evaluated. Since the genus Isoptericola was proposed after reclassification based on phylogenetic analysis, strains of Isoptericola have been continuously isolated from diverse environments and the importance of this genus in the ecosystem has been suggested by recent culturomic or metagenomic studies. The phylogenic relationships of the genus tended to be closer among strains that had been isolated from similar habitats. By analyzing the properties of published genome sequences of seven defined species in the genus, a large number of genes for carbohydrate hydrolysis and utilization, as well as several biosynthetic gene clusters for secondary metabolites, were identified. Genomic information of I. dokdonensis DS-3 together with comparative analysis of the genomes of Isoptericola provides insights into understanding this actinobacterial group with a potential for industrial applications.

Brevibacterium limosum sp. nov., Brevibacterium pigmenatum sp. nov., and Brevibacterium atlanticum sp. nov., three novel dye decolorizing actinobacteria isolated from ocean sediments: Shengxiang Pei , Siwen Niu , Fuquan Xie , Wenjing Wang , Shuang Zhang , Gaiyun Zhang; J. Microbiol. 2021;59(10):898-910. Published online September 7, 2021; DOI: https://doi.org/10.1007/s12275-021-1235-0

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Abstract: During a study of the marine actinobacterial biodiversity, a large number of Brevibacterium strains were isolated. Of these, five that have relatively low 16S rRNA gene similarity (98.5– 99.3%) with validly published Brevibacterium species, were chosen to determine taxonomic positions. On the basis of 16S rRNA gene sequence analysis and BOX-PCR fingerprinting, strains o2T, YB235T, and WO024T were selected as representative strains. Genomic analyses, including average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH), clearly differentiated the three strains from each other and from their closest relatives, with values ranging from 82.8% to 91.5% for ANI and from 26.7% to 46.5% for dDDH that below the threshold for species delineation. Strains YB235T, WO024T, and o2T all exhibited strong and efficient decolorization activity in congo red (CR) dyes, moderate decolorization activity in toluidine blue (TB) dyes and poor decolorization in reactive blue (RB) dyes. Genes coding for peroxidases and laccases were identified and accounted for these strains’ ability to effectively oxidize a variety of dyes with different chemical structures. Mining of the whole genome for secondary metabolite biosynthesis gene clusters revealed the presence of gene clusters encoding for bacteriocin, ectoine, NRPS, siderophore, T3PKS, terpene, and thiopeptide. Based on the phylogenetic, genotypic and phenotypic data, strains o2T, YB235T and WO024T clearly represent three novel taxa within the genus Brevibacterium, for which the names Brevibacterium limosum sp. nov. (type strain o2T = JCM 33844T = MCCC 1A09961T), Brevibacterium pigmenatum sp. nov. (type strain YB235T = JCM 33843T = MCCC 1A09842T) and Brevibacterium atlanticum sp. nov. (type strain WO024T = JCM 33846T = MCCC 1A16743T) are proposed.

Characterization of the effects of terminators and introns on recombinant gene expression in the basidiomycete Ceriporiopsis subvermispora: Dong Xuan Nguyen , Emi Nishisaka , Moriyuki Kawauchi , Takehito Nakazawa , Masahiro Sakamoto , Yoichi Honda; J. Microbiol. 2020;58(12):1037-1045. Published online September 30, 2020; DOI: https://doi.org/10.1007/s12275-020-0213-2

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Abstract: Terminators and introns are vital regulators of gene expression in many eukaryotes; however, the functional importance of these elements for controlling gene expression in Agaricomycetes remains unclear. In this study, the effects of Ceriporiopsis subvermispora terminators and introns on the expression of a recombinant hygromycin B phosphotransferase gene (hph) were characterized. Using a transient transformation system, we proved that a highly active terminator (e.g., the gpd terminator) is required for the efficient expression of the hph gene. Mutational analyses of the C. subvermispora gpd terminator revealed that hph expression was dictated by an A-rich region, which included a putative positioning element, and polyadenylation sites. In contrast, our results indicated that introns are not required for the expression of hph directed by the Csβ1-tub and Csgpd promoters in C. subvermispora. This study provides insights into the functions and cis-element requirements of transcriptional terminators in Agaricomycetes, which may be relevant for designing recombinant genes for this important fungal class.

Stenotrophomonas maltophilia outer membrane protein A induces epithelial cell apoptosis via mitochondrial pathways: Xin Wang , Yan Li , Xueping Tang , Xueyi Shang , Zunquan Zhao , Yongqiang Jiang , Yan Li; J. Microbiol. 2020;58(10):868-877. Published online September 2, 2020; DOI: https://doi.org/10.1007/s12275-020-0235-9

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Abstract: Stenotrophomonas maltophilia (S. maltophilia) is a common opportunistic pathogen in intensive care units and causes infections most often after surgeries in immune-compromised patients such as those undergoing chemotherapy. Outer membrane protein A (OmpA) is the most abundant of the outer membrane proteins in S. maltophilia. Previous studies on OmpA usually focus on its interaction with the host cells and its role in vaccine development. However, the impact of OmpA on the virulence of S. maltophilia to host cells and the effects on apoptosis remain unclear. In this study, we exposed purified recombinant S. maltophilia OmpA (rOmpA) to HEp-2 cells and investigated the effects of OmpA on epithelial cell apoptosis. Morphologic and flow cytometric analyses revealed that HEp-2 cells stimulated with rOmpA multiple apoptosis features, including nuclear roundness and pyknosis, chromatin aggregation, and phosphatidylserine eversion. We found that rOmpA regulated the protein levels of Bax and Bcl-xL in HEp-2 cells, leading to changes in mitochondria permeability and the release of cytochrome c and apoptosis-inducing factors into the cytoplasm. These subsequently activate the caspase-9/caspase-3 pathway that promote apoptosis. We also observed that rOmpA enhanced the generation of reactive oxygen species and increased intracellular Ca2+ levels in HEp-2 cells. Collectively, our data suggested that rOmpA induced epithelial cells apoptosis via mitochondrial pathways.

Comparative genomics of Lactobacillus species as bee symbionts and description of Lactobacillus bombintestini sp. nov., isolated from the gut of Bombus ignitus: Jun Heo , Soo-Jin Kim , Jeong-Seon Kim , Seung-Beom Hong , Soon-Wo Kwon; J. Microbiol. 2020;58(6):445-455. Published online March 28, 2020; DOI: https://doi.org/10.1007/s12275-020-9596-3

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Abstract: The Lactobacillus genus is widely used for fermentation of plant materials and dairy products. These species are typically found in highly specialized environments, with the bee gut serving as one of the niche locations in which Lactobacillus is detected. Lactobacillus species isolated from the bee gut and bee-related habitats were phylogenetically classified into three distinct groups, Lactobacillus kunkeei, Firm-4, and Firm-5. The L. kunkeei group was clearly differentiated from other members of the Lactobacillus buchneri group isolated from non-bee habitats. In comparison with non-bee members of the L. buchneri group, three bee-symbiotic Lactobacillus groups had a small-sized genome with low G + C content and showed a sharp reduction in the number of genes involved in energy production, carbohydrate transport and metabolism, and amino acid transport and metabolism. In addition, all three groups lacked the mutY gene, which encodes A/G-specific adenine glycosylase. The phylogenetic dendrogram based on the presence or absence of 1,199 functional genes indicated that these bee-symbiotic groups experienced convergent evolution. The occurrence of convergent evolution is thought to stem from the three bee-symbiotic groups sharing a similar habitat, i.e., the bee gut. The causative factor underlying genomic reduction was postulated to be mutY, which was absent in all three groups. Here, a novel strain, BHWM-4T, isolated from the gut of Bombus ignites was studied using polyphasic taxonomy and classified as a new member of the L. kunkeei group. The strain was Gram-positive, facultative anaerobic, and rod-shaped. The 16S ribosomal RNA gene sequence and genome analysis revealed that strain BHWM-4T was clustered into the L. kunkeei group, forming a compact cluster with L. kunkeei and Lactobacillus apinorum. Biochemical, chemotaxonomic, and genotypic data of strain BHWM-4T supports the proposal of a novel species, Lactobacillus bombintestini sp. nov., whose type strain is BHWM-4T (= KACC 19317T = NBRC 113067T).

Published Erratum

Erratum to: Physiological roles of catalases Cat1 and Cat2 in Myxococcus xanthus: Yoshio Kimura , Yuri Yoshioka , Kie Toshikuni; J. Microbiol. 2023;61(2):271-271.; DOI: https://doi.org/10.1007/s12275-023-00025-9

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