• Nonlinear Functional Analysis and Applications
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• 제28권3호
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• pp.659-670
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• 2023

In this paper, we study the distributed optimal control problem of a coupled system of the host-pathogen model. The system consists of the density of the susceptible host, the density of the infected host, and the density of pathogen particles. Our main goal is to minimize the infected density and also to decrease the cost of the drugs administered. First, we prove the existence and uniqueness of solutions for the proposed problem. Then, the existence of the optimal control is established and necessary optimality conditions are also derived.

• Journal of Microbiology and Biotechnology
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• 제27권1호
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• pp.171-178
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• 2017

A series of novel effector molecules secreted by the type three secretion system (T3SS) of Shigella spp. have been reported in recent years. In this study, a proteomic approach was applied to study T3SS effectors systematically. First, proteins secreted by the S. flexneri wild-type strain after Congo Red induction were separated and identified using two-dimensional electrophoresis to display the relative abundance of all kinds of early effectors for the first time. Then, a gene deletion mutant of known virulence repressor (OspD1) and a gene overexpressed mutant of two known virulence activators (MxiE and IpgC) were constructed and analyzed to discover potential late effectors. Furthermore, the supernatant proteins of gene deletion mutants of two known translocators (IpaB and IpaD), which would constantly secrete effectors, were also analyzed. Among all of the secreted proteins identified in our study, IpaH1.4, IpaH_5, and IpaH_7 have not been reported before. These proteomics data of the secreted effectors will be valuable to understand the pathogenesis of S. flexneri.

• Molecules and Cells
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• 제28권4호
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• pp.321-329
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• 2009

Rapid production of nitric oxide (NO) and reactive oxygen species (ROS) has been implicated in the regulation of innate immunity in plants. A potato calcium-dependent protein kinase (StCDPK5) activates an NADPH oxidase StRBOHA to D by direct phosphorylation of N-terminal regions, and heterologous expression of StCDPK5 and StRBOHs in Nicotiana benthamiana results in oxidative burst. The transgenic potato plants that carry a constitutively active StCDPK5 driven by a pathogen-inducible promoter of the potato showed high resistance to late blight pathogen Phytophthora infestans accompanied by HR-like cell death and $H_2O_2$ accumulation in the attacked cells. In contrast, these plants showed high susceptibility to early blight necrotrophic pathogen Alternaria solani, suggesting that oxidative burst confers high resistance to biotrophic pathogen, but high susceptibility to necrotrophic pathogen. NO and ROS synergistically function in defense responses. Two MAPK cascades, MEK2-SIPK and cytokinesis-related MEK1-NTF6, are involved in the induction of NbRBOHB gene in N. benthamiana. On the other hand, NO burst is regulated by the MEK2-SIPK cascade. Conditional activation of SIPK in potato plants induces oxidative and NO bursts, and confers resistance to both biotrophic and necrotrophic pathogens, indicating the plants may have obtained during evolution the signaling pathway which regulates both NO and ROS production to adapt to wide-spectrum pathogens.

• Journal of Microbiology and Biotechnology
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• 제33권2호
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• pp.235-241
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• 2023

Hyaluronidase (HAase) can enhance drug diffusion and dissipate edema by degrading hyaluronic acid (HA) in the extracellular matrix into unsaturated HA oligosaccharides in mammalian tissues. Microorganisms are recognized as valuable sources of HAase. In this study, a new hyaluronate lyase (HAaseD) from Bacillus sp. CQMU-D was expressed in Escherichia coli BL21, purified, and characterized. The results showed that HAaseD belonged to the polysaccharide lyase (PL) 8 family and had a molecular weight of 123 kDa. HAaseD could degrade chondroitin sulfate (CS) -A, CS-B, CS-C, and HA, with the highest activity toward HA. The optimum temperature and pH value of HAaseD were 40℃ and 7.0, respectively. In addition, HAaseD retained stability in an alkaline environment and displayed higher activity with appropriate concentrations of metal ions. Moreover, HAaseD was an endolytic hyaluronate lyase that could degrade HA to produce unsaturated HA oligosaccharides. Together, our findings indicate that HAaseD from Bacillus sp. CQMU-D is a new hyaluronate lyase and with excellent potential for application in industrial production.

• 한국식물병리학회:학술대회논문집
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• 한국식물병리학회 2000년도 추계 학술발표회
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• pp.13.2-13
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• 2000

• The Plant Pathology Journal
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• 제31권4호
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• pp.421-427
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• 2015

Citrus scab disease is one of the destructive diseases that reduce the value of fruit for the fresh market. We analyzed the process of symptom development after infection with scab pathogen $Elsino{\ddot{e}}$ fawcettii in the susceptible satsuma mandarin leaves to observe the structural modification against pathogen. The cuticle and epidermal cells along with 3-5 layers of mesophyll tissue were degraded 1-2 days post inoculation. Surrounding peripheral cells of degraded tissues grew rapidly and then enveloped the necrotic area along with the growing conidia. Cross sections through the lesion revealed hyphal colonization in epidermis and mesophyll tissues. In response to the pathogen colonization, host cell walls were lignified, inner cells were rapidly compartmentalized and a semi-circular boundary was formed that separated the infected region from the non-infected region, and finally prevented the intercellular pathogen spread.

• 미생물학회지
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• 제7권1호
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• pp.22-28
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• 1969

Twenty-nine specimens of the infected plans were collected from areas through the country since 1967 to 1968. We report here four unrecorded causla organisms of powdery and their hosts which were identified in this work. The results as as follows : 1. Microsphaera diffusa Cooke et Peck (M.magnoliae Sawoda) (Host:Magnolia obovata Thunb.) 2. Sphaerotheca humili (de Condolle0Burill. (Host: Spirea sp.) 3. Phyllactinea fraxini (de Condolle)Homma. (Host : Betuls sp.) 4. Uncinula sengorui.Salmon.(Host : Celastrus orbiculatus, Thunb.) * Six unrecorded host 1. Altemisia japonica. Thunb. (Pathogen : Erysiohe cichoracearum DC.) 2. Aster tataricus. L. (Pathogen :Sohaerotheca fuliginea (Schlechtendahl) Poll. 3. Dohlia variabilis Defont. (Pathogen :Sphaerotheeca fuliginea (schlechtendahl) poll. 5. Helianthus ammues (Pathogen :Spherotheca fuliginea schlechtendahl) poll. 6. Solanum melangera L. (Pathogen : Erysiphe cichoracearum DC.)

• 한국식물병리학회지
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• 제14권2호
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• pp.145-149
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• 1998

Four nonpathogenic isolates of Fusarium oxysporum isolated from spinach showed suppressive effect on the occurrence of the Fusarium wilt of spinach caused by F. oxysporum f. sp. sprinaciae, among which NF01 controlled the disease most effectively. And NF01 was not pathogenic to tomato, cucumber, radish and spinach. This isolate was further tested for the biological control of the disease. The isolate was not inhibitory to the growth of the pathogen on potato sucrose agar medium, however the Fusarium wilt disease occurred less by drenching spore suspension of the nonpathogenic isolate. The control effect of the isolate was higher at lower inoculum level of the pathogen than at the higher inoculum level, and in the pretreatments than the simultaneous treatment of the isolate with the pathogen inoculation. The nit mutants of the isolate were easily formed on chlorate containing media, and was reisolated selectively as nit mutant from infected soil and plants. The reisolation rate of the isolate as opposed to pathogen was high at preinoculated soil and plants relative to the simultaneous inoculation of the isolate with the pathogen.

• IMMUNE NETWORK
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• 제21권6호
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• pp.40.1-40.20
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• 2021

Mycobacteroides abscessus (previously Mycobacterium abscessus; Mabc), one of rapidly growing nontuberculous mycobacteria (NTM), is an important pathogen of NTM pulmonary diseases (NTM-PDs) in both immunocompetent and immunocompromised individuals. Mabc infection is chronic and often challenging to treat due to drug resistance, motivating the development of new therapeutics. Despite this, there is a lack of understanding of the relationship between Mabc and the immune system. This review highlights recent progress in the molecular architecture of Mabc and host interactions. We discuss several microbial components that take advantage of host immune defenses, host defense pathways that can overcome Mabc pathogenesis, and how host-pathogen interactions determine the outcomes of Mabc infection. Understanding the molecular mechanisms underlying host-pathogen interactions during Mabc infection will enable the identification of biomarkers and/or drugs to control immune pathogenesis and protect against NTM infection.

• Journal of Biosystems Engineering
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• 제39권2호
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• pp.111-114
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• 2014

Purpose: This review aims to introduce aptamers and the methods of its development to improve the sensitivity and selectivity to target bacteria. In this review, we have highlighted current developments and directions in the pathogen detection based on aptamers. Background: Aptamers, the specific nucleic acid sequences, can bind to targets with high affinity and specificity. Some of researches on the use of aptamers for the detection of pathogen have been reported in recent years. Aptamers have more applicability than antibodies for the development of pathogen detection using biosensor; such as easy to synthesis and labeling, lack of immunogenicity, and a low cost of production. However, only few reports on the development and use of aptamers for the detection of pathogen have been published. Review: Aptamers specific to pathogen are obtained by whole-cell systematic evolution of ligands by exponential enrichment (SELEX) process. SELEX process is composed of screening random oligonucleotide bound with target cells, multiple separation and amplification of nucleic acids, final identification of the best sequences. For improving those affinity and selectivity to target bacteria, optimization of multiple separating process to remove unbounded oligonucleotides from aptamer candidates and sorting process by flow cytometry are required.