• Journal of Veterinary Science
• /
• v.23 no.1
• /
• pp.8.1-8.15
• /
• 2022

Background: Brucella infection induces brucellosis, a zoonotic disease. The intracellular circulation process and virulence of Brucella mainly depend on its type IV secretion system (T4SS) expressing secretory effectors. Secreted protein BspJ is a nucleomodulin of Brucella that invades the host cell nucleus. BspJ mediates host energy synthesis and apoptosis through interaction with proteins. However, the mechanism of BspJ as it affects the intracellular survival of Brucella remains to be clarified. Objectives: To verify the functions of nucleomodulin BspJ in Brucella's intracellular infection cycles. Methods: Constructed Brucella abortus BspJ gene deletion strain (B. abortus ∆BspJ) and complement strain (B. abortus pBspJ) and studied their roles in the proliferation of Brucella both in vivo and in vitro. Results: BspJ gene deletion reduced the survival and intracellular proliferation of Brucella at the replicating Brucella-containing vacuoles (rBCV) stage. Compared with the parent strain, the colonization ability of the bacteria in mice was significantly reduced, causing less inflammatory infiltration and pathological damage. We also found that the knockout of BspJ altered the secretion of cytokines (interleukin [IL]-6, IL-1β, IL-10, tumor necrosis factor-α, interferon-γ) in host cells and in mice to affect the intracellular survival of Brucella. Conclusions: BspJ is extremely important for the circulatory proliferation of Brucella in the host, and it may be involved in a previously unknown mechanism of Brucella's intracellular survival.

• 한국균학회소식:학술대회논문집
• /
• 2015.05a
• /
• pp.13-13
• /
• 2015

Rice blast fungus, Magnaporthe oryzae, is the most destructive pathogen of rice in the world. This fungus has a biotrophic phase early in infection and switches to a necrotrophic lifestyle after host cell death. During the biotrophic phase, the fungus competes with host for nutrients and oxygen. Continuous uptake of oxygen is essential for successful establishment of blast disease of this pathogen. Here, we report transcriptional responses of the fungus to oxygen limitation. Transcriptome analysis using RNA-Seq identified 1,047 up-regulated genes in response to hypoxia. Those genes were involved in mycelial development, sterol biosynthesis, and metal ion transport based on hierarchical GO terms and well-conserved among three different fungal species. In addition, null mutants of three hypoxia-responsive genes were generated and tested for their roles on fungal development and pathogenicity. The mutants for a sterol regulatory element-binding protein gene, MoSRE1, and C4 methyl sterol oxidase gene, ERG25, exhibited increased sensitivity to hypoxia-mimetic agent, increased conidiation, and delayed invasive growth within host cells, suggesting important roles in fungal development. However, such defects did not cause any significant decrease in disease severity. The other null mutant for alcohol dehydrogenase gene, MoADH1, showed no defect in the hypoxia-mimic condition and fungal development. Taken together, this comprehensive transcriptional profiling in response to a hypoxia condition with experimental validations would provide new insights on fungal development and pathogenicity in plant pathogenic fungi.

• IMMUNE NETWORK
• /
• v.14 no.1
• /
• pp.38-44
• /
• 2014

K/BxN serum can transfer arthritis to normal mice owing to the abundant autoantibodies it contains, which trigger innate inflammatory cascades in joints. Little is known about whether gut-residing microbes affect host susceptibility to autoantibody-mediated arthritis. To address this, we fed C57BL/6 mice with water containing a mixture of antibiotics (ampicillin, vancomycin, neomycin, and metronidazol) for 2 weeks and then injected them with K/BxN serum. Antibiotic treatment significantly reduced the amount of bacterial genomic DNA isolated from fecal samples, in particular a gene encoding 16S ribosomal RNA derived from segmented filamentous bacteria. Arthritic signs, as indicated by the arthritic index and ankle thickness, were significantly attenuated in antibiotic-treated mice compared with untreated controls. Peyer's patches and mesenteric lymph nodes from antibiotic-treated mice contained fewer IL-17-expressing cells than those from untreated mice. Antibiotic treatment reduced serum C3 deposition in vitro via the alternative complement pathway. IL-$17^{-/-}$ congenic C57BL/6 mice were less susceptible to K/BxN serum-transferred arthritis than their wild-type littermates, but were still responsive to treatment with antibiotics. These results suggest that gut-residing microbes, including segmented filamentous bacteria, induce IL-17 production in GALT and complement activation via the alternative complement pathway, which cause the host to be more susceptible to autoantibody-mediated arthritis.

• Korean Journal of Poultry Science
• /
• v.39 no.1
• /
• pp.17-25
• /
• 2012

Coccidiosis control programs such as vaccines or in-feed anticoccidials are commonly practiced in the poultry industry to improve growth performance and health of commercial broiler chickens. In this study, we assessed the effects of various coccidiosis control programs (e.g., in ovo vaccination, synthetic chemicals, and antibiotic ionophores) on immune status of broiler chickens vaccinated against infectious bronchitis virus and Newcastle disease virus (ND) and raised on an Eimeria-contaminated used litter. In general, the levels of ${\alpha}$-1-acid glycoprotein, an acute phase protein, were altered by the treatments when measured at 34 days of age. Splenocyte subpopulations and serum antibody titers against ND were altered by various coccidiosis control programs. In-ovo-vaccinated chickens exhibited highest mitogenic response when their spleen cells were stimulated with concanavalin A (Con A) at 7 days of age. It is clear from this study that the type of coccidiosis control program influenced various aspects of innate and adaptive immune parameters of broiler chickens. Further studies will be necessary to delineate the underlying relationship between the type of coccidiosis control program and host immune system and to understand the role of other external environmental factors such as gut microbiota on host-pathogen interaction in various disease control programs.

• Korean Journal of Microbiology
• /
• v.23 no.1
• /
• pp.9-12
• /
• 1985

As a part of the host cell development for a amplified recombinant trp operon, $aroP^-$ mutation was introduced in a E. coli host strain. $aroP^-$ mutation was induced by transposon Tn10 and transduced into the E. coli host cell by bacteriophage P1Kc. The effect of $aroP^-$ mutation on the excretion of tryptophan in E. coli $trpR^{-ts}/ColE_1 -trp^+$ cells was investigated. Mutant lacking the general aromatic transport system was resistant to ${\beta}-2-thienylalanine\;(2{\times}10^{-4}\;M)$, p-fluorophenylalanine $(2{\times}10^{-4}M)$, or 5-methyltryptophan $(2{\times}10^{-4}\;M.)[^3H]-tryptophan$ uptake of the $aroP^-$ mutant strain was reduced considerably as compared with $aroP^+$ counterpart. The rate of $[^3H]-tryptophan$ uptake of the $aroP^-$ mutant strain treated with $NaN_3(3{\times}10^{-2}\;M)$ was much less affected than that of $aroP^+$ counterpart. The $aroP^-$ transductants increased the tryptophan excretion from E. coli $trpR^{-ts}/ColE_1 -trp^+$ four times more than $aroP^+$ counterpart.

• Parasites, Hosts and Diseases
• /
• v.49 no.4
• /
• pp.431-436
• /
• 2011

The onset, severity, and ultimate outcome of malaria infection are influenced by parasite-expressed virulence factors as well as by individual host responses to these determinants. In both humans and mice, liver injury follows parasite entry, persisting to the erythrocytic stage in the case of infection with the fatal strain of Plasmodium falciparum. Hepatic nuclear factor (HNF)-$1{\alpha}$ is a master regulator of not only the liver damage and adaptive responses but also diverse metabolic functions. In this study, we analyzed the expression of host HNF-$1{\alpha}$ in relation to malaria infection and evaluated its interaction with the 5'-untranslated region of subtilisin-like protease 2 (subtilase, Sub2). Recombinant human HNF-$1{\alpha}$ expressed by a lentiviral vector (LV HNF-$1{\alpha}$) was introduced into mice. Interestingly, differences in the activity of the 5'-untranslated region of the Pf-Sub2 promoter were detected in 293T cells, and LV HNF-$1{\alpha}$ was observed to influence promoter activity, suggesting that host HNF-$1{\alpha}$ interacts with the Sub2 gene.

• Pediatric Gastroenterology, Hepatology & Nutrition
• /
• v.11 no.sup1
• /
• pp.83-92
• /
• 2008

Helicobacter pylori is the causative agent of chronic gastritis and has a role in the pathogenesis of peptic ulcer diseases, and gastric cancer. There have been reports suggesting a close link between these gastroduodenal disorders and a state of vitamin C deficiency. In this paper, the past, present and future perspectives on H. pylori infection and vitamin C will be discussed under the following view points. Since the ecological niche of H. pylori is the mucus layer and intercellular junctions of the gastric epithelium, the various kinds of host inflammatory cells motivated by the local and systemic immune responses cannot eliminate the microorganisms. When the invading foreign body is not removed, despite full activation of defense mechanisms, adverse consequences of the immune responses develop on the host gastric mucosa. The reasons for the body vitamin C depletion could be explained as follows; 1) the increased vitamin C consumption by increased oxygen free radical production through the prolonged hypersensitivity reactions in the gastric mucosa, 2) the increased vitamin C oxidation by the nitrite which is formed from nitrate reduction by the intragastric bacteria proliferated in the hypochlorhydric gastric cavity, 3) the strong ${\gamma}$-glutamyltranspeptidase activity of H. pylori which depletes the glutathiones in gastric mucosa. Depletion of glutathiones in the stomach favors irreversible oxidative destruction of ascorbic acid. Both persistent inflammatory burdens in the stomach by H. pylori and resultant vitamin C depletions synergistically and uninhibitedly might aggravate the hypothetical sequence of gastric carcinogenesis: atrophic gastritis${\rightarrow}$intestinal metaplasia${\rightarrow}$dysplasia${\rightarrow}$gastric adenocarcinoma. High intake of vitamin C could reverse the hypothetical sequence of the gastric carcinogenesis via direct and indirect effects on H. pylori and host-parasite relationships.

• Mycobiology
• /
• v.36 no.4
• /
• pp.236-241
• /
• 2008

The colonization of an arbuscular mycorrhizal fungus Glomus intraradices BEG110 in the soil caused a decrease in disease severity in cucumber plants after fungal inoculation with Colletotrichum orbiculare. In order to illustrate the resistance mechanism mediated by G. intraradices BEG110, infection patterns caused by C. orbiculare in the leaves of cucumber plants and the host cellular responses were characterized. These properties were characterized using transmission electron microscopy on the leaves of cucumber plants grown in soil colonized with G. intraradices BEG110. In the untreated plants, inter- and intra-cellular fungal hyphae were observed throughout the leaf tissues during both the biotrophic and necrotrophic phases of infection. The cytoplasm of fungal hyphae appeared intact during the biotrophic phase, suggesting no defense response against the fungus. However, several typical resistance responses were observed in the plants when treated with G. intraradices BEG110 including the formation of sheaths around the intracellular hyphae or a thickening of host cell walls. These observations suggest that the resistance mediated by G. intraradices BEG110 most often occurs in the symplast of the host cells rather than in the apoplast. In addition, this resistance is similar to those mediated by biotic inducers such as plant growth promoting rhizobacteria.

• Microbiology and Biotechnology Letters
• /
• v.15 no.6
• /
• pp.396-401
• /
• 1987

Protein productivities of a cloned gene ($\beta$-galactosidase) and the cultural performances of two recombinant Escherichia coli strains, which use different host-vector systems, were studied. E. coli JM109/pTBG10 strain which carries Tac promoter had higher protein productivity than E. coli MH3000 (pRKc1857)/pASI(lacZ) strain which carries pL promoter. Induction of protein syn-thesis was optimum at the initial-and mid-logarithmic growth phases for both strains. Oxygen demand was observed to be very high during the cloned gene expression, and could be alleviated to some extent through pH control. The ratio of specific growth rates of plasmid-harboring to plasmidfree cell, $\mu$+ /$\mu$-, of the high productivity strain was observed to be lower than that of the low productivity one. Plasmid stability was analyzed for 20-30 generations, and it was found that the traction of plasmid-harboring cells dropped to l0% level in about 25 generations for both strains when the cloned gene expression was induced.

• Microbiology and Biotechnology Letters
• /
• v.17 no.3
• /
• pp.213-218
• /
• 1989

To investigate the possibility of using alkalophilic Bacillus sp. K-11 as a host for molecular cloning, plasmid pUB110 and pBD64 were introduced into alkalophilic Bacillus sp. K-17 by protoplast transformation system. Protoplasts of Bacillus sp. K-11 were prepared by treatment with 200 $\mu\textrm{g}$/$m\ell$ Iysozyme in SMM buffer containing 0.4M sucrose. Optimal temperature, pH and culture time for protoplast formation were 4$0^{\circ}C$, 7.0 and 4hrs, respectively. Cell wall was regenerated efficiently on DM3 medium containing 0.8% agar and 0.5M sodium succinate. Under these conditions for protoplast formation and regeneration, the highest transformation efficiency was obtained with cells incubated for 4hrs, and using 30%(V/V) of 40%(W/V) PEG6,000, In characteristics of transfer-mants, plasmid pUB110 was more stable than plasmid pBD64 in Bacillus sp. K-17. Maximum xylanase production of both transformants carrying pUB110 and pBD64, respectively was similar, but under the same conditions, enzyme secretion by transformant carrying pUB110 was earlier than that of transformant carrying pBD64.