• Journal of Microbiology and Biotechnology
• /
• 제31권1호
• /
• pp.25-32
• /
• 2021

Inflammatory reactions activated by lipopolysaccharide (LPS) of gram-negative bacteria can lead to severe septic shock. With the recent emergence of multidrug-resistant gram-negative bacteria and a lack of efficient ways to treat resulting infections, there is a need to develop novel anti-endotoxin agents. Antimicrobial peptides have been noticed as potential therapeutic molecules for bacterial infection and as candidates for new antibiotic drugs. We previously designed the 9-meric antimicrobial peptide Pro9-3 and it showed high antimicrobial activity against gram-negative bacteria. Here, to further examine its potency as an anti-endotoxin agent, we examined the anti-endotoxin activities of Pro9-3 and elucidated its mechanism of action. We performed a dye-leakage experiment and BODIPY-TR cadaverine and limulus amebocyte lysate assays for Pro9-3 as well as its lysine-substituted analogue and their enantiomers. The results confirmed that Pro9-3 targets the bacterial membrane and the arginine residues play key roles in its antimicrobial activity. Pro9-3 showed excellent LPS-neutralizing activity and LPS-binding properties, which were superior to those of other peptides. Saturation transfer difference-nuclear magnetic resonance experiments to explore the interaction between LPS and Pro9-3 revealed that Trp3 and Tlr7 in Pro9-3 are critical for attracting Pro9-3 to the LPS in the gram-negative bacterial membrane. Moreover, the anti-septic effect of Pro9-3 in vivo was investigated using an LPS-induced endotoxemia mouse model, demonstrating its dual activities: antibacterial activity against gram-negative bacteria and immunosuppressive effect preventing LPS-induced endotoxemia. Collectively, these results confirmed the therapeutic potential of Pro9-3 against infection of gram-negative bacteria.

• Journal of Animal Science and Technology
• /
• 제65권2호
• /
• pp.441-458
• /
• 2023

The poultry industry, which produces excellent sources of protein, suffers enormous economic damage from diseases. To solve this problem, research is being conducted on the early detection of infection according to the behavioral characteristics of poultry. The purpose of this study was to evaluate the potential of a non-movement behavior observation method to detect sick chickens. Forty 1-day-old Ross 308 males were used in the experiments, and an isolator equipped with an Internet Protocol (IP) camera was fabricated for observation. The chickens were inoculated with Salmonella enterica serovar Gallinarum A18-GCVP-014, the causative agent of fowl typhoid (FT), at 14 days of age, which is a vulnerable period for FT infection. The chickens were continuously observed with an IP camera for 2 weeks after inoculation, chickens that did not move for more than 30 minutes were detected and marked according to the algorithm. FT infection was confirmed based on clinical symptoms, analysis of cardiac, spleen and liver lesion scores, pathogen re-isolation, and serological analysis. As a result, clinical symptoms were first observed four days after inoculation, and dead chickens were observed on day six. Eleven days after inoculation, the number of clinical symptoms gradually decreased, indicating a state of recovery. For lesion scores, dead chickens scored 3.57 and live chickens scored 2.38. Pathogens were re-isolated in 37 out of 40 chickens, and hemagglutination test was positive in seven out of 26 chickens. The IP camera applied with the algorithm detected about 83% of the chickens that died in advance through non-movement behavior observation. Therefore, observation of non-movement behavior is one of the ways to detect infected chickens in advance, and it appears to have potential for the development of remote broiler management system.

• Parasites, Hosts and Diseases
• /
• 제23권1호
• /
• pp.79-86
• /
• 1985

In order to judge appropriately the suitability as the second intermediate host of Clonorchis sinensis, the present experiments were proposed to survey the metacercaria of C. sinensis in the fish host, Cuztriculus eigenmanni, in the 6eld, and to observe, by experimental infection of the fish with Clonorchis cercaria, the penetrating ability of the cercaria, maturity, the process of degeneration and extinction, and infectivity of the metacercaria. The following is a brie summary of the leading facts gained through the experiments. 1. All the ten fish (mean body weight $13.4{\pm}3.439$) which were caught in Ok-ku irrigation reservoir were in acted with the metacercariae and the average number of the metacercariae found in the fish body/gram was 4.55. 2. The Bish was easily subject to invasion of the cercaria, and the examination of the cercariae after having the fish infected disclosed that 5:l hours after the infection, all of the cercariae formed their cysts in muscle and the metacercariae kept growing, that 7 days later the metacercariae were found folding their bodies twice, and that in 15 days the characteristic structure of the metacercariae was complete and made a vigorous rotary movement intermittently. 3. In the case of control fish, Pseudorasbora parka, both penetrating ability of the cercariae and the infective degree of the metacercariae to control host were stronger as compared with the 5sh host because that the control fish had higher suceptibility to C. sinensis. 4. Afterwards, the metacercariae in the fish host came to a state of maturity and beyond this stage some metacercariae started the Process of degeneration and extinction in as early as 30 days, and as more days elapsed, mortality of the metacercariae was not uniformly increased but difference of mortality appeared to be according to the individual of Ssh host. That is, in 390, 540 and 586 days, all of the metacercariae in the fish hosts became dead, meanwhile almost all of those found in the fish host of 596 days after the infection survived (mortality; 8, 51%) , Percentage of orally administered metacercariae developing to maturity in rabbit is 10.465 in the last case. 5. As the days were progressed the shapes of the metacercariae in the fish host tended to change from ellipsoid to almost round shapes, the length became shorter while the width was wider. The results shown above revealed that C. eigenmanni was, though it could not be proper host than p. larva. suitable as the second intermediate host in addition to our previous observation results.

• Parasites, Hosts and Diseases
• /
• 제23권1호
• /
• pp.165-172
• /
• 1985

Naegleria fowleri의 감염에 의한 생쥐의 원발성 아메바성 뇌수막염의 발생에 prednisolone투여가 어떠한 영향을 주는가를 관찰한 바 다음과 같은 결론을 얻었다. 1. 각 실험군 별로 $1{\times}10^5$의 N. fowleri를 감염시킨 후 생존기간을 관찰하였더니, prednisolone을 투여한 제1군의 평균 생존기간은 10.2일, 제2군은 10.6일, 제3군은은 11.3일로써 prednisolon을 투여한 군이 비투여군에 비하여 유의하게 생존기간이 단축됨을 알 수 있었으며, prednisolon투여군인 제1, 2, 3군 사이에 유의한 차이는 없었으나 전투여군인 제1군에서 생존시간이 단축되는 경향을 나타내었다. 2. 각 실험군 별로 감염 이후 20일까지 체중의 변화를 관찰한 결과, prenisolone 투여군에서는 서로 비슷한 양상을 나타내었는데 투여하는 시기부터 어느 정도 감소하다가 일정한 시간이 지나면서 회복현상을 나타내었다. 또한 prednisolon만 투여한 제 IV군에 비하여 제1, 2, 3군에서 체중이 더욱 심하게 감소하는 현상을 나타내었다. 그리고 대조군은 감염 8일 후부터 감소하기는 하였으나 큰 차이는 없는 것으로 보아 체중감소현상은 주로 prednisolone에 의해 영향을 받는 것으로 보인다. 3. Prednisolone 투여한 감염군은 대조군에 비하여 뇌와 폐조직에서 비교적 심한 병변이 나타났음을 알 수 있었다. 4. 감염된 생쥐의 임상증세는 감염 후 며칠이 지나면 머리를 비비고 고개를 떨구며, 식욕부진이 나타나 먹이를 먹지 않다가 발작이 오고, 빈사상태가 되어 사망하게 된다. 대부분의 생쥐에서 이러한 증세가 나타나는데, prednisolone 투여군에서는 감염 5일 이후부터 증세가 나타나는 경향을 보였고, 대조군은 감염 8일 이후에야 나타나 10일경에 사망하였다. 이상의 결과를 종합항 보면 prednisolone을 투여하여 인위적으로 면역반응을 억제시켜 줄 경우 N. fowleri에 감염된 생쥐의 생존기간은 단축되고 병변도 더욱 심하게 나타나며, 감염전에 투여해 주는 것이 가장 치명적인 영향을 줄 수 있음을 알 수 있었다.

• 대한수의학회지
• /
• 제46권4호
• /
• pp.327-335
• /
• 2006

A stable and reliable Helicobacter pylori (H. pylori) infection animal model would be necessary for evaluating vaccine efficacy and helpful for understanding the pathological mechanism of the organism. The aim of the present study is to investigate the effect of ethanol treatment prior to H. pylori inoculation on associated gastric mucosal injury and to establish ethanol-pretreating animal model to study H. pylori infection. Male Mongolian gerbils were used for the study. H. pylori was orally inoculated after 12 h fasting. 3 h prior to H. pylori inoculation, a group of gerbils was orally treated with absolute ethanol, 60% and 40% ethanol respectively. Another group of animals was treated either with H. pylori culture media alone or with different concentrations of ethanol plus culture media. Gerbils were killed 4 or 8 weeks after H. pylori inoculation. The colonization of H. pylori was confirmed by both histological examination and rapid urease test. Mucosal damage was evaluated grossly and histologically according to the criteria. The colonization of H. pylori and pathological changes in gastric mucosa of the animals were also observed. Although no significant change to the gastric mucose was observed in the animals treated either with H. pylori culture media alone or with different concentrations of ethanol plus culture media, persistent H. pylori infection was seen in the mucosa and mucosal leucocyte infiltration and severe epithelial damage was observed in the Helicobacter and ethanol + Helicobacter groups after 4 weeks. The gross and histological scores were higher in the ethanol + Helicobacter than in the Helicobacter alone group. As the results, ethanol-pretreatment with 60% concentration induced severe pathogenic changes by H. pylori infection in 5 weeks-old Mongolian gerbils. These results suggested that ethanol-pretreatment before H. pylori inoculation could increase the severity of gastric mucosal inflammation and enhance the colonization of H. pylori. The established ethanol-pretreating animal model would contribute to screen new drugs against H. pylori and be used as an useful tool for various animal experiments with H. pylori strains.

• Journal of Microbiology and Biotechnology
• /
• 제24권10호
• /
• pp.1327-1336
• /
• 2014

Bacillus amyloliquefaciens strain NJZJSB3 has shown antagonism of several phytopathogens in vitro, especially Sclerotinia sclerotiorum. Both the broth culture and cell suspension of strain NJZJSB3 could completely protect the detached leaves of canola (Brassica napus) from S. sclerotiorum infection. In pot experiments, the application of strain NJZJSB3 cell suspension ($10^8CFU/ml$) decreased the disease incidence by 83.3%, a result similar to commercially available fungicide (Dimetachlone). In order to investigate the potential biocontrol mechanisms of strain NJZJSB3, the nonvolatile antifungal compounds it produces were identified as iturin homologs using HPLC-ESI-MS. Antifungal volatile organic compounds were identified by gas chromatography-mass spectrometry. The detected volatiles toluene, phenol, and benzothiazole showed antifungal effects against S. sclerotiorum in chemical control experiments. Strain NJZJSB3 also produced biofilm, siderophores and cell-wall-degrading enzymes (protease and ${\beta}$-1,3-glucanase). These results suggest that strain NJZJSB3 can be a tremendous potential agent for the biological control of sclerotinia stem rot.

• 한국미생물·생명공학회지
• /
• 제50권4호
• /
• pp.512-521
• /
• 2022

Since the main symptoms of COVID-19 involve the respiratory system, the infection rate of this disease is predicted to be higher in patients with other respiratory conditions such as allergic rhinitis. In such a situation, it will be meaningful to conduct research on an allergy treatment that has fewer side effects and can effectively reduce allergy symptoms. Here, we prepared experimental samples under various fermentation conditions with mixed extracts of six medicinal plants. To examine the anti-allergic efficacy of these samples, an egg albumin-induced allergic rhinitis animal model experiment, a serum histamine and IgE experiment, and a COX and LO inhibitory activity experiment were conducted. As a result of animal experiments, OVA+SP-4 showed superior efficacy compared to OVA+SP-1 in nasal rubbing and sneezing experiments and had anti-allergic efficacy similar to that of OVA-cetirizine. The serum histamine concentration of OVA+SP-4 was also 1.3 times higher than that of the OVA+cetirizine group, showing a high histamine reduction ability, and IgE showed the same trend. An analysis of COX inhibitory efficacy also confirmed that COX-1 and COX-2 inhibitory efficacy is high, and the longer the fermentation time, the higher the antiallergic efficacy. The composition proposed by this study is expected to have a significant effect on sustainable allergy prevention and treatment in the future by applying it to human patients.

• 한국식물병리학회지
• /
• 제1권2호
• /
• pp.109-114
• /
• 1985

밀양 지역의 애멸구 2회 성충의 바이러스 보독충율은 검은줄무늬오갈병이 $13.6\%$, 줄무늬잎마름병이 $6.7\%$이었다. 본 논에서 애멸구 2회 성충은 5월 29일부터 나타나기 시작하여 6월 13일에 최성기였는데, 이때의 주당애멸구 서식수는 추청벼, 낙동벼가 19.6, 19.3마리로 높았으나 삼강벼, 청청벼는 4.9 및 7.4마리로 비교적 낮았고, 이앙 바로 뒤의 벌레수는 극히 적었으며 이앙이 빠를수록 벌레수가 많은 경향이었다. 바이러스의 못자리감염은 5월 30일까지는 인정되지 않았으나, 그 후부터 감염이 인정되었는데 6월 20일 이앙구는 검은줄무늬오갈병의 못자리감염율이 가장 높은 경향이었다. 바이러스 본논감염율은 이앙이 빠를수록 높은 경향이었으며 그 가운데서도 5월 20일 이앙이 가장 높았고 7월 10일 이앙이 가장 낮았다. 검은줄무늬오갈병은 5월 10일 이앙이 5월 20일과 5월 30일 이앙에 비하여 발병증가가 완만하였으나, 줄무늬잎마름병은 5월 10일 이앙이 발병증가가 빠른 경향이었다.

• 대한의생명과학회지
• /
• 제5권2호
• /
• pp.147-153
• /
• 1999

본 연구는 흰쥐에 호르텐스극구흡충 피낭유충을 흰쥐에게 실험적으로 감염시켜 감염기간에 따른 항체 생산 유무를 규명하였다. 감염 흰쥐의 혈청을 기간별로 채취하여 IgG및 IgM 항체가를 ELISA 법으로 측정하였으며, 또한 이의 진단적 이용가치를 평가하고 이들에 대한 상관성을 검토한 결과는 다음과 같다. 즉, 기간별 특이 IgG 항체가는 0.13$\pm$0.014 (mean$\pm$S.D.)에서 0.4803$\pm$0.073까지의 분포를 보였으며 감염 제 28일에 최고치 (0.4803$\pm$0.073)를 보였다 (p<0.05). 호르텐스극구흡충에 감염된 백서를 통해 매주 얻은 특이 IgM 항체가는 0.16$\pm$0.034 (mean$\pm$S.D.)에서 0.4093$\pm$0.084까지의 분포를 보였으며 감염 제 7일에 증가하여 감염 제 14일에 최고치 (0.4093$\pm$0.084)를 보였다(p<0.05). 이상의 결과를 종합할 때 호르텐스극구흡충 감염시 흰쥐 혈청의 IgM은 감염 초기에 급속한 증가를 보였으나 IgG는 감염 이후 계속 증가하는 경향을 보였다.

• Journal of Microbiology and Biotechnology
• /
• 제31권5호
• /
• pp.667-675
• /
• 2021

Streptococcus agalactiae is an important bacterial pathogen and causative agent of diseases including neonatal sepsis and meningitis, as well as infections in healthy adults and pregnant women. Although antibiotic treatments effectively relieve symptoms, the emergence and transmission of multidrug-resistant strains indicate the need for an effective immunotherapy. Effector T helper (Th) 17 cells are a relatively newly discovered subpopulation of helper CD4⁺ T lymphocytes, and which, by expressing interleukin (IL)-17A, play crucial roles in host defenses against a variety of pathogens, including bacteria and viruses. However, whether S. agalactiae infection can induce the differentiation of CD4⁺ T cells into Th17 cells, and whether IL-17A can play an effective role against S. agalactiae infections, are still unclear. In this study, we analyzed the responses of CD4⁺ T cells and their defensive effects after S. agalactiae infection. The results showed that S. agalactiae infection induces not only the formation of Th1 cells expressing interferon (IFN)-γ, but also the differentiation of mouse splenic CD4⁺ T cells into Th17 cells, which highly express IL-17A. In addition, the bacterial load of S. agalactiae was significantly increased and decreased in organs as determined by antibody neutralization and IL-17A addition experiments, respectively. The results confirmed that IL-17A is required by the host to defend against S. agalactiae and that it plays an important role in effectively eliminating S. agalactiae. Our findings therefore prompt us to adopt effective methods to regulate the expression of IL-17A as a potent strategy for the prevention and treatment of S. agalactiae infection.