Journal of Microbiology

Review

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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19 Citations

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

Caspase-3 inhibitor inhibits enterovirus D68 production: Wenbo Huo , Jinghua Yu , Chunyu Liu , Ting Wu , Yue Wang , Xiangling Meng , Fengmei Song , Shuxia Zhang , Ying Su , Yumeng Liu , Jinming Liu , Xiaoyan Yu , Shucheng Hua; J. Microbiol. 2020;58(9):812-820. Published online September 1, 2020; DOI: https://doi.org/10.1007/s12275-020-0241-y

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Abstract: Enterovirus D68 (EVD68) is an emerging pathogen that recently caused a large worldwide outbreak of severe respiratory disease in children. However, the relationship between EVD68 and host cells remains unclear. Caspases are involved in cell death, immune response, and even viral production. We found that caspase-3 was activated during EVD68 replication to induce apoptosis. Caspase-3 inhibitor (Z-DEVDFMK) inhibited viral production, protected host cells from the cytopathic effects of EVD68 infection, and prevented EVD68 from regulating the host cell cycle at G0/G1. Meanwhile, caspase-3 activator (PAC-1) increased EVD68 production. EVD68 infection therefore activates caspase-3 for virus production. This knowledge provides a potential direction for the prevention and treatment of disease related to EVD68.

Performance comparison of fecal preservative and stock solutions for gut microbiome storage at room temperature: Chanhyeok Park , Kyeong Eui Yun , Jeong Min Chu , Ji Yeon Lee , Chang Pyo Hong , Young Do Nam , Jinuk Jeong , Kyudong Han , Yong Ju Ahn; J. Microbiol. 2020;58(8):703-710. Published online June 25, 2020; DOI: https://doi.org/10.1007/s12275-020-0092-6

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Abstract: The gut microbiome, which is symbiotic within the human body, assists in human digestion. It plays significant roles in identifying intestinal disease as well as in maintaining a healthy body with functional immune and metabolic activities. To confirm the consistency of fecal intestinal microbial research, it is necessary to study the changes in intestinal microbial flora according to the fecal collection solution and storage period. We collected fecal samples from three healthy Korean adults. To examine the efficacy of fecal collection solution, we used NBgene-Gut, OMNIgene-Gut, 70% ethanol (Ethanol-70%), and RNAlater. The samples were stored for up to two months at room temperature using three different
methods
, and we observed changes in microbial communities over time. We analyzed clusters of changes in the microbial flora by observing fecal stock solutions and metagenome sequencing performed over time. In particular, we confirmed the profiling of alpha and beta diversity and microbial classification according to the differences in intestinal environment among individuals. We also confirmed that the microbial profile remained stable for two months and that the microbial profile did not change significantly over time. In addition, our results suggest the possibility of verifying microbial profiling even for long-term storage of a single sample. In conclusion, collecting fecal samples using a stock solution rather than freezing feces seems to be relatively reproducible and stable for GUT metagenome analysis. Therefore, stock solution tubes in intestinal microbial research can be used without problems.

Pten gene deletion in intestinal epithelial cells enhances susceptibility to Salmonella Typhimurium infection in mice: Cody Howe , Jonathon Mitchell , Su Jin Kim , Eunok Im , Sang Hoon Rhee; J. Microbiol. 2019;57(11):1012-1018. Published online September 25, 2019; DOI: https://doi.org/10.1007/s12275-019-9320-3

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Abstract: Although phosphatase and tensin homolog (PTEN) is typically considered a tumor-suppressor gene, it was recently suggested that PTEN regulates TLR5-induced immune and inflammatory responses in intestinal epithelial cells (IECs), suggesting an immunomodulatory function of PTEN in the gut. However, this alternative function of PTEN has not yet been evaluated in an in vivo context of protection against enteropathogenic bacteria. To address this, we utilized IECrestricted Pten knockout (PtenΔIEC/ΔIEC) and littermate Pten+/+ mice. These mice were subjected to the streptomycin-pretreated mouse model of Salmonella infection, and subsequently given an oral gavage of a low inoculum (2 × 104 CFU) of Salmonella enterica serovar Typhimurium (S. Typhimurium). This bacterial infection not only increased the mortality of PtenΔIEC/ΔIEC mice compared to Pten+/+ mice, but also induced deleterious gastrointestinal inflammation in PtenΔIEC/ΔIEC mice manifested by massive histological damage to the intestinal mucosa. S. Typhimurium infection upregulated pro-inflammatory cytokine production in the intestine of PtenΔIEC/ΔIEC mice compared to controls. Furthermore, bacterial loads were greatly increased in the liver, mesenteric lymph node, and spleen of PtenΔIEC/ΔIEC mice compared to controls. Together, these results suggest that IEC-restricted Pten deficiency renders the host greatly susceptible to Salmonella infection and support an immuneregulatory role of PTEN in the gut.

β-1,3-Glucan/CR3/SYK pathway-dependent LC3B-II accumulation enhanced the fungicidal activity in human neutrophils: Ding Li , Changsen Bai , Qing Zhang , Zheng Li , Di Shao , Xichuan Li; J. Microbiol. 2019;57(4):263-270. Published online February 5, 2019; DOI: https://doi.org/10.1007/s12275-019-8298-1

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8 Citations

Abstract: Since molecular genotyping has been established for the Candida species, studies have found that a single Candida strain (endemic strain) can persist over a long period of time and results in the spread of nosocomial invasive candidiasis without general characteristics of horizontal transmissions. Our previous study also found the existence of endemic strains in a cancer center in Tianjin, China. In the current study, we performed further investigation on endemic and non-endemic Candida albicans strains, with the aim of explaining the higher morbidity of endemic strains. In an in vivo experiment, mice infected with endemic strains showed significantly shorter survival time and higher kidney fungal burdens compared to mice infected with non-endemic strains. In an in vitro experiment, the killing percentage of neutrophils to endemic strains was significantly lower than that to non-endemic strains, which is positively linked to the ratio of LC3B-II/I in neutrophils. An immunofluorescence assay showed more β-1,3-glucan exposure on the cell walls of nonendemic strains compared to endemic strains. After blocking the β-glucan receptor (CR3) or inhibiting downstream kinase (SYK) in neutrophils, the killing percent to C. albicans (regardless of endemic and non-endemic strains) and the ratio of LC3B-II/I of neutrophils were significantly decreased. These data suggested that the killing capability of neutrophils to C. albicans was monitored by β-1,3-glucan via CR3/SYK pathway-dependent LC3B-II accumulation and provided an explanation for the variable killing capability of neutrophils to different strains of C. albicans, which would be beneficial in improving infection control and therapeutic strategies for invasive candidiasis.

Diet-induced obese mice exhibit altered immune responses to early Salmonella Typhimurium oral infection: Ricardo Ernesto Ramírez-Orozco , Elena Franco Robles , Victoriano Pérez Vázquez , Joel Ramírez Emiliano , Marco Antonio Hernández Luna , Sergio López Briones; J. Microbiol. 2018;56(9):673-682. Published online August 23, 2018; DOI: https://doi.org/10.1007/s12275-018-8083-6

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Abstract: Obesity is a chronic disease associated with different metabolic diseases as well as alterations in immune cell function. It is characterized by a chronic systemic low grade inflammation. There are several studies demonstrating the influence of obesity on the impaired immune response to infection. However, it is not completely clear whether the obese environment influences the development or maintenance of the immune response against infections. The aim of this study was to determine how obesity induced by a high-fat diet affects the immune response to an early oral Salmonella infection. Four groups of mice were kept in separate cages. Two of these designated as controls, fed with a normal diet; whereas other two groups were fed with a high fat diet for 10 weeks. Some mice were used for Salmonella oral infection. After 7 days of oral infection with S. Thypimurium the proportions of spleen cell subsets expressing activation markers in normal diet and HFD obese mice were stained with monoclonal antibodies and analyzed by flow cytometry. Also, mRNA levels of different cytokines were quantified by RT-PCR. It was found that obesity affects the function of the immune system against an early oral Salmonella infection, decreasing NK cells, altering the expression of activation molecules as well as cytokines mRNA levels. Interestingly, the expression some activation molecules on T lymphocytes was reestablished after Salmonella infection, but not the CD25 expression. Immune alterations could lead to immunosuppression or increased susceptibility to infections in HFD obese mice.

Review

REVIEW] Intestinal microbiota and the immune system in metabolic diseases: Panida Sittipo , Stefani Lobionda , Yun Kyung Lee , Craig L. Maynard; J. Microbiol. 2018;56(3):154-162. Published online February 28, 2018; DOI: https://doi.org/10.1007/s12275-018-7548-y

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91 Citations

Abstract: The intestinal microbiota is comprised of millions of microorganisms that reside in the gastrointestinal tract and consistently interact with the host. Host factors such as diet and disease status affect the composition of the microbiota, while the microbiota itself produces metabolites that can further manipulate host physiology. Dysbiosis of the intestinal microbiota has been characterized in patients with certain metabolic diseases, some of which involve damage to the host intestinal epithelial barrier and alterations in the immune system. In this review, we will discuss the consequences of dietdependent bacterial dysbiosis in the gastrointestinal tract, and how the associated interaction with epithelial and immune cells impacts metabolic diseases.

Research Support, Non-U.S. Gov'ts

Oral administration of Lactobacillus plantarum lysates attenuates the development of atopic dermatitis lesions in mouse models: Hangeun Kim , Hye Rim Kim , Na-Ra Kim , Bong Jun Jeong , Jong Suk Lee , Soojin Jang , Dae Kyun Chung; J. Microbiol. 2015;53(1):47-52. Published online December 4, 2014; DOI: https://doi.org/10.1007/s12275-015-4483-z

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Abstract: Lactobacillus plantarum is a well-documented probiotic that has been used in clinical trials for the regulation of the immune system and treatment of gastrointestinal diseases. In this study, we evaluated the effects of L. plantarum cell lysates on the immune regulation through the in vitro and in vivo studies. L. plantarum lysates were prepared by sonication
method
, and we observed that the repetition of disruption step increased indicator components within the bacterial lysates. Indicator components might affect TNF-α production. L. plantarum lysates did not induce TNF-α production, while LPS-induced TNF-α production was dramatically inhibited in a sonication-dependent manner in THP-1 cells. Oral administration of L. plantarum lysates effectively attenuated the horny layer formation and decreased epidermal thickening in NC/Nga mice skin. The damage to barrier function after the 8 weeks oral administration was reduced by L. plantarum lysates as compared to that in the atopic dermatitis (AD) mice. Further study revealed that L. plantarum lysates polarized Th1 response via induction of IL-12 and IFN-γ production and inhibition of IL-4 and IgE production in NC/Nga mice. Together, our results suggest that L. plantarum lysates are remarkable material for host homeostasis and it could be used for the treatment of inflammatory diseases.

Altered mRNA Levels of MOV10, A3G, and IFN-α in Patients with Chronic Hepatitis B: Zhi-Wei Song , Yan-Xiu Ma , Li-Juan Fu , Bao-qing Fu , Xu Teng , Si-Jia Chen , Wei-Zhen Xu , Hong-Xi Gu; J. Microbiol. 2014;52(6):510-514. Published online May 29, 2014; DOI: https://doi.org/10.1007/s12275-014-3467-8

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10 Citations

Abstract: To explore the relationship of the MOV10, A3G, and IFN-α mRNA levels with chronic hepatitis B virus (HBV) infection, Blood samples from 96 patients with chronic hepatitis B (CHB) and 21 healthy individuals as control were collected. HBV DNA load and aminotransferase in the serum were tested using real time PCR and velocity methods, respectively. The MOV10, A3G, and IFN-α mRNA levels in the peripheral blood mononuclear cells (PBMC) were examined through qRT-PCR. The MOV10, A3G, and IFN-α mRNA levels in CHB group was significantly lower than those in the control group (P<0.01, P<0.05, P<0.01, respectively). The A3G mRNA level in the high-HBV DNA load group was lower than that in the low-HBV DNA load group (P<0.05). However, no statistical difference was found in the MOV10 and IFN-α mRNA levels between the two HBV DNA load groups. Furthermore, the MOV10 mRNA level showed positive correlation with IFN-α in the control group. These results indicated that the expression of the innate immune factors MOV10, A3G, and IFN-α is affected by chronic HBV infection.

Sequential Immunosuppressive Activities of Bacterial Secondary Metabolites from the Entomopahogenic Bacterium Xenorhabdus nematophila: Seonghyeon Eom , Youngjin Park , Yonggyun Kim; J. Microbiol. 2014;52(2):161-168. Published online February 1, 2014; DOI: https://doi.org/10.1007/s12275-014-3251-9

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38 Citations

Abstract: The entomopathogenic bacterium Xenorhabdus nematophila secretes at least eight bacterial metabolites that play crucial roles suppressing target insect immune responses by inhibiting eicosanoid biosynthesis. We analyzed sequential changes in bacterial metabolite production during bacterial growth and analyzed their individual immunosuppressive activities against the insect host, Spodoptera exigua. X. nematophila exhibited a typical bacterial growth pattern in both insect host and culture medium, and eight metabolites were secreted at different time points. At the early growth phase (6–12 h), Ac-FGV and PHPP were detected in significant amounts in the culture broth. At this early phase, both Ac-FGV (18 μg/ml) and oxindole (110 μg/ml) levels significantly inhibited phenoloxidase and phospholipase A2 activities in S. exigua hemolymph. At the late growth phase (12–36 h), all eight metabolites were detected at significant levels (10–140 μg/ml) in the culture broth and were sufficient to induce hemocyte toxicity. These results suggest that X. nematophila sequentially produces immunosuppressive metabolites that might sequentially and cooperatively inhibit different steps of insect immune responses.

Sublingual Administration of Bacteria-Expressed Influenza Virus Hemagglutinin 1 (HA1) Induces Protection against Infection with 2009 Pandemic H1N1 Influenza Virus: Byoung-Shik Shim , Jung-ah Choi , Ho-Hyun Song , Sung-Moo Park , In Su Cheon , Ji-Eun Jang , Sun Je Woo , Chung Hwan Cho , Min-Suk Song , Hyemi Kim , Kyung Joo Song , Jae Myun Lee , Suhng Wook Kim , Dae Sub Song , Young Ki Choi , Jae-Ouk Kim , Huan Huu Nguyen , Dong Wook Kim , Young Yil Bahk , Cheol-Heui Yun , Man Ki Song; J. Microbiol. 2013;51(1):130-135. Published online March 2, 2013; DOI: https://doi.org/10.1007/s12275-013-2399-z

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11 Citations

Abstract: Influenza viruses are respiratory pathogens that continue to pose a significantly high risk of morbidity and mortality of humans worldwide. Vaccination is one of the most effective strategies for minimizing damages by influenza outbreaks. In addition, rapid development and production of efficient vaccine with convenient administration is required in case of influenza pandemic. In this study, we generated recombinant influenza virus hemagglutinin protein 1 (sHA1) of 2009 pandemic influenza virus as a vaccine candidate using a wellestablished bacterial expression system and administered it into mice via sublingual (s.l.) route. We found that s.l. immunization with the recombinant sHA1 plus cholera toxin (CT) induced mucosal antibodies as well as systemic antibodies including neutralizing Abs and provided complete protection against infection with pandemic influenza virus A/CA/04/09 (H1N1) in mice. Indeed, the protection efficacy was comparable with that induced by intramuscular (i.m.) immunization route utilized as general administration route of influenza vaccine. These results suggest that s.l. vaccination with the recombinant non-glycosylated HA1 protein offers an alternative strategy to control influenza outbreaks including pandemics.

Immunoprophylactic Effects of Shiitake Mushroom (Lentinula edodes) against Bordetella bronchiseptica in Mice: Bock-Gie Jung , Jin-A Lee , Bong-Joo Lee; J. Microbiol. 2012;50(6):1003-1008. Published online December 30, 2012; DOI: https://doi.org/10.1007/s12275-012-2365-1

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Abstract: Antimicrobials are used as feed additives to improve growth performance and to prevent subclinical disease challenge in industrial animals. However, these drugs can lead to the development of resistant strains of bacteria. Shiitake mushrooms (SM) (Lentinula edodes) have long been popular as a health food in East Asia. Moreover, SM-derived polysaccharides are well-known as immunostimulants that possess antimicrobial properties. The aim of the present study was to evaluate the immunoprophylactic effects of SM against Bordetella bronchiseptica infection in mice as an initial step towards the development of eco-friendly feed additives to reduce the use of antimicrobials. Although SM had no effect on body weight gain under the un-infected conditions, SM alleviated progressive weight loss and helped in the recovery of body weight in B. bronchiseptica infected mice. Dietary supplementation with SM reinforced bacterial clearance in the infected mice. Of note, SM markedly increased the percentage of various T lymphocytes and the relative mRNA expression levels of tumor necrosis factor-α and interferon-γ in the bronchial lymph node early in the infection. Taken together, these findings suggest that SM could help in the improvement of body weight gain during B. bronchiseptica infection and may enhance the protective immune activity against a subclinical disease challenge, such as B. bronchiseptica infection in mice, probably by a strong stimulation of non-specific immune responses. Hence, SM may provide an alternative to reduce use of antimicrobials. Confirmation of the beneficial effects of SM as a feed additive is now required in industrial animals.

Phospholipase A2 Inhibitors in Bacterial Culture Broth Enhance Pathogenicity of a Fungus Nomuraea rileyi: Jung-A Park , Yonggyun Kim; J. Microbiol. 2012;50(4):644-651. Published online July 21, 2012; DOI: https://doi.org/10.1007/s12275-012-2108-3

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Abstract: An entomopathogenic fungus, Nomuraea rileyi, was isolated and its identity was confirmed by its internal transcribed spacer DNA sequence. The isolated N. rileyi exhibited a specific pathogenicity to lepidopteran species. This study was focused on enhancing the fungal pathogenicity by using immunosuppressive agents. In response to infection of N. rileyi, Spodoptera exigua larvae significantly induced catalytic activity of phospholipase A2 (PLA2) in three immune-associated tissues, namely hemocytes, fat body, and hemolymph plasma. Furthermore, the infected S. exigua larvae induced transcription of several antimicrobial peptide (AMP) genes. Two entomopathogenic bacteria, Xenorhabdus nematophila (Xn) and Photorhabdus temperata subsp. temperata (Ptt), possessed specific PLA2-inhibitory activities and their culture broths significantly inhibited the enzyme activities in hemocytes, fat body, and plasma of S. exigua. In addition, the bacterial metabolites inhibited transcription of AMP genes in S. exigua that would normally respond to the immune challenge by N. rileyi. The immunosuppressive effect of Xn or Ptt bacterial broth resulted in significant enhancement of the fungal pathogenicity against late instar larvae of S. exigua and Plutella xylostella. The effect of such a mixture was confirmed by field assay against two lepidopteran species. These results suggest that the bacterial and fungal mixture can be applied to develop a novel biopesticide to control lepidopteran species.

Immune Response Induced by ppGpp-Defective Salmonella enterica serovar Gallinarum in Chickens: Sang-Ik Park , Jae-Ho Jeong , Hyon E. Choy , Joon Haeng Rhee , Hee-Sam Na , Tae-Hoon Lee , Moon Her , Kyoung-Oh Cho , Yeongjin Hong; J. Microbiol. 2010;48(5):674-681. Published online November 3, 2010; DOI: https://doi.org/10.1007/s12275-010-0179-6

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Abstract: To protect chickens from typhoid caused by Salmonella enterica serovar Gallinarum (S. Gallinarum), the attenuated 9R strain has been used in the field as a vaccine. However, safety concerns have been raised because the mutations in 9R are undefined while its efficacy is still a question under debate. A global regulator, ppGpp, synthesized by RelA and SpoT, has been shown to induce various virulence genes in S. Gallinarum (Jeong et al., 2008). In this study, two mutant strains defective in ppGpp-synthesis were constructed in wild-type S. Gallinarum (∆ppGpp) and 9R strain (9R-∆ppGpp) backgrounds and tested as live vaccines in chickens. After oral inoculation, the LD50 values of ∆ppGpp and 9R-∆ppGpp were approximately 5×1010 colony forming unit (CFU) similarly as 9R strain, which was ~105-fold higher than that of the wildtype S. Gallinarum strain. Immunological analyses revealed immunization with either of the two attenuated ppGpp-defective strains induced significant antibody responses, the production of antibody-secreting B cells in blood, proliferation of CD4+ and CD8+ T cells in the spleen, and splenic expression of proinflammatory cytokines, such as IFN-γ and TGF-β4, at levels comparable to the 9R strain. Chickens immunized with the mutants (1×108 CFU) were 80% protected against oral challenge with 1×109 wild-type virulent bacteria (4,000-fold LD50 dose), similar to the level of protection achieved by 9R immunization. Based on these data, live attenuated ∆ppGpp-defective strains may serve as novel vaccines to control fowl typhoid in chickens.

Newly Identified CpG ODNs, M5-30 and M6-395, Stimulate MouseNewly Identified CpG ODNs, M5-30 and M6-395, Stimulate Mouse Immune Cells to Secrete TNF-α and Enhance Th1-Mediated Immunity: Sun-Shim Choi , Eunkyung Chung , Yu-Jin Jung; J. Microbiol. 2010;48(4):512-517. Published online August 20, 2010; DOI: https://doi.org/10.1007/s12275-010-0053-6

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Abstract: Bacterial CpG motifs are known to induce both innate and adaptive immunity in infected hosts via toll-like receptor 9 (TLR9). Because small oligonucleotides (ODNs) mimicking bacterial CpG motifs are easily synthesized, they have found use as immunomodulatory agents in a number of disease models. We have developed a novel bioinformatics approach to identify effective CpG ODN sequences and evaluate their function as TLR9 ligands in a murine system. Among the CpG ODNs we identified, M5-30 and M6-395 showed significant ability to stimulate TNF-α and IFN-γ production in a mouse macrophage cell line and mouse splenocytes, respectively. We also found that these CpG ODNs activated cells through the canonical NF-κB signaling pathway. Moreover, both CpG ODNs were able to induce Th1-mediated immunity in Mycobacterium tuberculosis (Mtb)-infected mice. Our results demonstrate that M5-30 and M6-395 function as TLR9-specific ligands, making them useful in the study of TLR9 functionality and signaling in mice.

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