• 대한수의학회지
• /
• 제47권1호
• /
• pp.77-84
• /
• 2007

Helicobacter pylori (H. pylori) is an important bacterial pathogen that causes chronic gastritisand is associated with gastroduodenal ulcer disease, adenocarcinoma of the distal stomach, and gastricH. pylori infection associated with host agehave not been well-defined in human. To evaluate the difference in host susceptibility to infection in relationto age of acquisition of H. pylori infection, we designed an experiment involving inoculation of H. pyloriATC 43504 at different ages of Mongolian gerbils. H. pylori was inoculated at 5 weeks and 18 monthsof age, as representatives of early and late infection, respectively. Animals were sacrificed 1 week and 4weeks after challenge, and the stomach was removed from each animal for bacterial culture, histologicalexamination, and polymerase chain reaction test. 5 week-old gerbils revealed infection andmaintained continuously its infection until 4 weeks. However, old gerbils did not maintained H. pyloriinfection. These data suggest the insusceptibility of H. pylori in old Mongolian gerbils and the importanceof animal ages for successful animal experimental infection. Also, the results demonstrated that earlyinfection of H. pylori increases its host susceptibility, as compared to the case with later infection, possiblybecause of differences in host gastric mucosal factors and imunologic responses.

• 한국식품위생안전성학회지
• /
• 제7권2호
• /
• pp.91-97
• /
• 1992

Diazinon which is one of the most beavily used organophosphate pesticide in Korea, was examined for its effects on the murine host defense system. Immunotoxicological assay parameters adopted in this study were carbon clearance for macrophage function, susceptibility to tumor challenge, and pathotoxicological indicators, Subchronic exposure of pesticide to rodents resulted in the suppression of immune functions, enhancement of susceptibility to tumor challenge, and moderate histological changes of lymphoid organ without any significant alteration of clinical status.

• Molecules and Cells
• /
• 제46권11호
• /
• pp.710-724
• /
• 2023

The plant defense responses to microbial infection are tightly regulated and integrated with the developmental program for optimal resources allocation. Notably, the defense-associated hormone salicylic acid (SA) acts as a promoter of flowering while several plant pathogens actively target the flowering signaling pathway to promote their virulence or dissemination. Ralstonia pseudosolanacearum inject tens of effectors in the host cells that collectively promote bacterial proliferation in plant tissues. Here, we characterized the function of the broadly conserved R. pseudosolanacearum effector RipL, through heterologous expression in Arabidopsis thaliana. RipL-expressing transgenic lines presented a delayed flowering, which correlated with a low expression of flowering regulator genes. Delayed flowering was also observed in Nicotiana benthamiana plants transiently expressing RipL. In parallel, RipL promoted plant susceptibility to virulent strains of Pseudomonas syringae in the effector-expressing lines or when delivered by the type III secretion system. Unexpectedly, SA accumulation and SA-dependent immune signaling were not significantly affected by RipL expression. Rather, the RNA-seq analysis of infected RipL-expressing lines revealed that the overall amplitude of the transcriptional response was dampened, suggesting that RipL could promote plant susceptibility in an SA-independent manner. Further elucidation of the molecular mechanisms underpinning RipL effect on flowering and immunity may reveal novel effector functions in host cells.

• The Plant Pathology Journal
• /
• 제27권3호
• /
• pp.232-341
• /
• 2011

Pink snow mold, caused by Microdochium nivale, is a major disease on cool season turfgrasses in golf courses in northern Unites States. The relative susceptibility of 17 commercial cultivars of three bentgrass species (creeping, colonial and velvet bentgrass) to Microdochium nivale and the aggressiveness of M. nivale eight isolates obtained from infected turfgrasses on golf courses in Wisconsin were evaluated under controlled conditions. For the field trial, susceptibility of 2 year-old 12 commercial bentgrass cultivars was evaluated after inoculating three M. nivale isolates in the fields. There were significant differences in disease severities among the three bentgrass species, particularly between tetraploids (creeping and colonial) and diploid (velvet) species, and among cultivars within each species, indicating that there are varying levels of susceptibility in species and cultivars to M. nivale. Host resistance by days of cold hardening was confirmed, by detecting the resistance by 30 days of cold hardening treatments. In field trial, susceptibility of 12 bentgrass cultivars was highly correlated to the results obtained from growth chamber experiments. The positive correlation of the susceptibility between growth chamber experiments and field trials demonstrates that the growth chamber method is a useful technique for saving time, space and labor to evaluate efficiently pink snow mold susceptibility of bentgrass cultivars. This study could be applied to evaluating susceptibility of bentgrass to pink snow mold and also predicting a prospective evaluation of bentgrass cultivars to pink snow mold in fields in a breeding program.

• Journal of Periodontal and Implant Science
• /
• 제43권1호
• /
• pp.3-11
• /
• 2013

Periodontitis is a chronic inflammation of periodontal tissue caused by subgingival plaque-associated bacteria. Periodontitis has long been understood to be the result of an excessive host response to plaque bacteria. In addition, periodontal pathogens have been regarded as the causative agents that induce a hyperinflammatory response from the host. In this brief review, host-microbe interaction of nonperiodontopathic versus periodontopathic bacteria with innate immune components encountered in the gingival sulcus will be described. In particular, we will describe the susceptibility of these microbes to antimicrobial peptides (AMPs) and phagocytosis by neutrophils, the induction of tissue-destructive mediators from neutrophils, the induction of AMPs and interleukin (IL)-8 from gingival epithelial cells, and the pattern recognition receptors that mediate the regulation of AMPs and IL-8 in gingival epithelial cells. This review indicates that true periodontal pathogens are poor activators/suppressors of a host immune response, and they evade host defense mechanisms.

• Journal of Microbiology
• /
• 제45권2호
• /
• pp.133-138
• /
• 2007

This study addresses the susceptibility of Spodoptera frugiperda (Sf9 and Sf21), Trichoplusia ni (Hi5), and S. exigua (Se301) cells to the Bombyx mori nucleopolyhedrovirus (BmNPV). Although these cells have classically been considered nonpermissive to BmNPV, the cytopathic effect, an increase in viral yield, and viral DNA synthesis by BmNPV were observed in Sf9, Sf21, and Hi5 cells, but not in Se301 cells. Very late gene expression by BmNPV in these cell lines was also detected via ${\beta}-galactosidase$ expression under the control of the polyhedrin promoter. Sf9 cells were most susceptible to BmNPV in all respects, followed by Sf21 and Hi5 cells in decreasing order, while the Se301 cells evidenced no distinct viral replication. This particular difference in viral susceptibility in each of the cell lines can be utilized for our understanding of the mechanisms underlying the host specificity of NPVs.

• The Plant Pathology Journal
• /
• 제40권2호
• /
• pp.225-232
• /
• 2024

The microbiomes of two important rice cultivars in Vietnam which differ by their susceptibility to the bacterial leaf blight (BLB) disease were analyzed through 16S rRNA amplicon technology. A higher number of operational taxonomic units and alpha-diversity indices were shown in the BLB-resistant LA cultivar than in the BLB-susceptible TB cultivar. The BLB pathogen Xanthomonas was scantly found (0.003%) in the LA cultivar, whereas was in a significantly higher ratio in the TB cultivar (1.82%), reflecting the susceptibility to BLB of these cultivars. Of special interest was the genus Acholeplasma presented in the BLB-resistant LA cultivar at a high relative abundance (22.32%), however, was minor in the BLB-sensitive TB cultivar (0.09%), raising a question about its roles in controlling the Xanthomonas low in the LA cultivar. It is proposed that Acholeplasma once entered the host plant would hamper other phytopathogens, i.e. Xanthomonas, by yet unknown mechanisms, of which the triggering of the host plants to produce secondary metabolites against pathogens could be a testable hypothesis.

• Journal of Veterinary Science
• /
• 제22권3호
• /
• pp.36.1-36.12
• /
• 2021

Background: Mouse hepatitis virus (MHV) A59 is a highly infectious pathogen and starts in the respiratory tract and progresses to systemic infection in laboratory mice. The complement system is an important part of the host immune response to viral infection. It is not clear the role of the classical complement pathway in MHV infection. Objectives: The purpose of this study was to determine the importance of the classical pathway in coronavirus pathogenesis by comparing C1qa KO mice and wild-type mice. Methods: We generated a C1qa KO mouse using CRISPR/Cas9 technology and compared the susceptibility to MHV A59 infection between C1qa KO and wild-type mice. Histopathological and immunohistochemical changes, viral loads, and chemokine expressions in both mice were measured. Results: MHV A59-infected C1qa KO mice showed severe histopathological changes, such as hepatocellular necrosis and interstitial pneumonia, compared to MHV A59-infected wild-type mice. Virus copy numbers in the olfactory bulb, liver, and lungs of C1qa KO mice were significantly higher than those of wild-type mice. The increase in viral copy numbers in C1qa KO mice was consistent with the histopathologic changes in organs. These results indicate that C1qa deficiency enhances susceptibility to MHV A59 systemic infection in mice. In addition, this enhanced susceptibility effect is associated with dramatic elevations in spleen IFN-γ, MIP-1 α, and MCP-1 in C1qa KO mice. Conclusions: These data suggest that C1qa deficiency enhances susceptibility to MHV A59 systemic infection, and activation of the classical complement pathway may be important for protecting the host against MHV A59 infection.

• Parasites, Hosts and Diseases
• /
• 제39권4호
• /
• pp.329-332
• /
• 2001

More than 1,500 clams of Corbicula fluminea, the most favorable food source of freshwater bivalves in Korea, were collected from 5 localities to examine cercarial and metacercarial infection with Echinostoma cinetorchis. Although 3 clams infected with suspicious E. cinetorchis metacercariae out of 200 specimens collected at Kangjin, Chollanam-do were detected, no cercarial and metacercarial infections with E. cinetorchis were observed in field-collected Corbicula specimens. In the susceptibility experiments with laboratory-reared clams, those infected with miracidia of E. cinetorchis did not release their cercariae up to 60 days after infection. To confirm the identity of second intermediate host of E. cinetorchis experimentally, a total of 30 clams were exposed to the cercariae from Segmentina hemisphaerula that had been infected with miracidia of E. cinetorchis. The clams were susceptible to cercariae of E. cinetorchis with an infection rate of 93.3%. Metacercariae from clams taken more than 7 days after cercarial exposure were fed to rats (S/D strain), and adult worms of E. cinetorchis, characterized by 37-38 collar spines on the head crown, were recovered from the ileocecal regions. This is the first report of C. fluminea as a possible second intermediate host of E. cinetorchis.

• 생명과학회지
• /
• 제27권3호
• /
• pp.283-288
• /
• 2017

양돈산업에 있어 돼지 써코바이러스 2형(PCV2)의 복합감염으로 인한 이유자돈의 질병 피해가 막대하다. PCV2 감염에 대한 숙주의 민감도는 상이한 것으로 알려져 있으며, 따라서 숙주의 민감도를 구분하는 것은, 이를 이용한 숙주의 저항성 향상 연구에 필수이다. 본 연구의 목적은 이유자돈군의 혈액 내에서 PCV2 바이러스에 대한 숙주의 민감도를 구분 짓고 구명하는데 있었다. 본 연구에서는 자연적으로 바이러스에 감염된 10주령의 이유자돈군으로부터 혈청을 채취하여 PCV2 바이러스량과 항체가를 측정하고 혈구분석을 실시했다. 또한, 측정된 PCV2 바이러스량과 항체가를 기준으로 자돈군 내에서 저항성군과 민감성군을 선정하였고, 통계분석결과 저항성군에 비해 민감성군에서 백혈구 수가 현저히 줄어든 것을 확인하였다. 본 연구를 통해서 PCV2 감염에 대한 돼지의 민감도를 구분짓기 위한 PCV2 바이러스량과 항체가를 이용한 복합기준을 제시할 수 있었으며, 이유자돈군의 PCV2 관련 질병저항성 및 백혈구감소증을 확인할 수 있는 방법을 마련하였다.