• 한국동물위생학회지
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• 제14권1호
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• pp.27-40
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• 1991

In order to investigate the biological properties, pathogenicity and immune responses in artficially infected SPF chickens with Avian infectious bronchitis virus that was isolated from chickens showing IB like signs in southern region of Chung buk. Results obtained throuth the experiments are summarized as follows. 1. From 15 IB suspected cases, two strains of IB virus were isolated, one each from the tracheas and lungs. 2. Infectious bronchitis specific embryo lesions were observed after four serial passages of the isolates in chicken embryos. 3. The field isolates and M-41 strain of IB virus interfered with the replication of Newcastle disease virus in chicken embryos. 4. When specific pathogen free chickens, two week old, were inoculated with the IB virus isolates, clinical respiratory signs as dyspnea, coughing were observed. Airsacculitis was observed by necropsy. 5. AGP antibody positive rates of inoculated SPF chickens were highest on day 14 and lowest on day 36, while HI antibody responses were detected on day 14 in all Groups, the reinoculated Group was shown highest titers. 6. By Indirect immunofluorescence antibody assay of artificially infected SPF chickens, the viral antigens were detected in tissues of larynx, trachea and lung on the 4 th to 7 th days post inoculation.

• Journal of Microbiology and Biotechnology
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• 제30권10호
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• pp.1443-1457
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• 2020

The emergence and spread of antimicrobial resistance in pathogenic bacteria of fish and shellfish have caused serious concerns in the aquaculture industry, owing to the potential health risks to humans and animals. Among these bacteria, Aeromonas salmonicida, which is one of the most important primary pathogens in salmonids, is responsible for significant economic losses in the global aquaculture industry, especially in salmonid farming because of its severe infectivity and acquisition of antimicrobial resistance. Therefore, interest in the use of alternative approaches to prevent and control A. salmonicida infections has increased in recent years, and several applications of bacteriophages (phages) have provided promising results. For several decades, A. salmonicida and phages infecting this fish pathogen have been thoroughly investigated in various research areas including aquaculture. The general overview of phage usage to control bacterial diseases in aquaculture, including the general advantages of this strategy, has been clearly described in previous reviews. Therefore, this review specifically focuses on providing insights into the phages infecting A. salmonicida, from basic research to biotechnological application in aquaculture, as well as recent advances in the study of A. salmonicida.

• 한국동물위생학회지
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• 제25권1호
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• pp.87-96
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• 2002

In this study, we wanted to determine if the respirotropic JMK strain of infectious bronchitis virus(IBV), which has a spike glycoprotein gene that is 99% similar to the nephropathogenic Gray strain of IBV, could adapt and cause lesions in the kidney following intracloacal passage in chickens. Two day old specific pathogen free(SPF) cchickens were infected with Gray and JMK strains by the intraocular and cloacal route. Several tissue samples were collected at various times. Viruses were recovered from more tissues and earlier in the infection from chickens infected cloacally than chickens infected intraocularly. Virus was isolated from the kidney of chickens infected with Gray by the intraocular route and JMK by the intracloacal route, but not from chicken given JMK the intraocular route. Histopathologically, interstitial nephritis was observed in Gray infected chickens. However, viral RNA or antigen were not detected in the kidney by in situ hybridization and immunohistochemistry. We further passaged the JMK strain ten times in two day old SPF chickens using cloacal inoculation. We examined the virus titer and histopathological change in the kidney at each passage level. The amount of virus recovered from the kidney was stable throughout this serial passage and the passaged virus did not caused renal damage. Further, virus could not be isolated from the kidney when chickens were infected with the passaged virus by the intraocular route. We conclude that the JMK strain has a strict upper respiratory tract tropism since cloacal passage did not produce nephrotropism or nephropathogenicity.

• 한국어병학회지
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• 제25권3호
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• pp.143-150
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• 2012

Infectious haematopoietic necrosis virus (IHNV) is an important fish pathogen that infects both wild and cultured salmonids. Since the first isolation of IHNV from rainbow trout and masu salmon in 1991, a series of IHN disease outbreak has been reported in Korea. In 2011, we isolated two IHNV isolates from rainbow trout cultured in Korea. The full open-reading frame (ORF) encoding the glycoprotein (G) of them were sequenced and the amino acid sequences were phylogenetically analyzed. Phylogenetic analysis of the G revealed that both IHNV isolates were grouped into an Asian genogroup containing Korean IHNV isolates and Japanese IHNV isolates. However, based on their sequence variation, they were divided into different subgroup. While one isolate was similar to other Korean isolates, the other isolate showed a high level of similarity with Japanese isolates, suggesting the possibility of influx of new IHNV strain into Korea.

• 한국동물위생학회지
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• 제43권4호
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• pp.245-250
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• 2020

Infectious bovine keratoconjunctivitis (IBK) is the most common ocular disease in cattle, manifesting as corneal opacity, corneal ulcerations and potentially vision loss. The present report describes a 10-month-old Holstein Friesian heifer with IBK treated by systemic tulathromycin, and subconjunctival injection of penicillin and dexamethasone. We investigated changes in the hematological indices and microorganisms related to IBK after treatment. Neutrophils and monocytes decreased during recovery, so it was assumed that these two types of white cells are associated with IBK. Moraxella bovoculi was cleared in the eye, nasal cavity, and oral cavity after treatment. The distribution of M. bovoculi before treatment indicated that a combined systemic and subconjunctival treatment was necessary. The lesioned eye was found to be overwhelmed by Mycoplasma bovoculi, while pathogen abundance was reduced in the nasal cavity and oral cavities. These results suggest that antibiotic treatment can alter the composition and relative abundance of microorganisms.

• 한국잠사곤충학회지
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• 제13권1호
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• pp.35-47
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• 1971

최근 외국에서 Virus성 연화병을 발견하였으며 본병으로 인한 피해는 다를 연화병보다 매우 심하였음을 밝혔다. 그러나 우리나라에서는 거의 발병여부조차 밝혀지지 못하고 있는 것이다. 그리므로 본 연구에서 Virus성 연화병이 발생하는가를 생물학적검정과 전자현미경 관찰로 구명하였고 가잠을 어떠한 불량조건으로 사육하였을 때에 유발현상이 나타나는가를 조사하였다. 그러고 연화병의 Virus와 연화병 잠체에 분리한 Bacillus spp의 세균과의 기동작용 및 Virus의 잠좌내감염방지에 대하여 실험을 하였다. 그 결과를 요약하면 다음과 같다. 1) 우리나라에서 Virus성 연화병이 발생하였으며 그 병원체인 Virus 입자는 구형이고 직경이 26~30m$\mu$이었음을 동정하였다. 2) 누에를 식상불족으로 인한 영양장해를 입히게 하거나 3~4 영기의 고온다습환경에서 사육하면 광의의 유발현상이 뚜렷이 나타냈음을 인정하였다. 3) Virus 또는 세균을 단독접종한 경우보다 혼합접종한 경우는 잠복기간이 짧고 발병율이 높은 결과를 얻어 Virus에 세균과의 기동작용이 이루워졌음을 인정하였다. 4) Virus의 잠좌내감염방지에는 소석회를 사용함이 효과적방법이 였음을 인정하였다.

• Parasites, Hosts and Diseases
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• 제61권1호
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• pp.15-23
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• 2023

Concerns about foodborne illnesses caused by Kudoa septempunctata are steadily growing, but reports of K. septempunctata in clinical and food specimens related to food poisoning in Korea are limited. This study aimed to genetically identify K. septempunctata in patients with acute diarrhea and in clinical and food samples related to food poisoning caused by sashimi consumption. Both real-time and nested polymerase chain reaction assays were performed to detect K. septempunctata 18S and 28S rDNA genes in the stools of 348 patients with acute diarrhea, 11 samples (6 stool and 5 rectal swab samples) from patients with food poisoning, and 2 raw Paralichthys olivaceus samples collected from a restaurant where a food poisoning incident occurred. K. septempunctata was identified in 5 clinical specimens (4 stools and 1 rectal swab) and 1 P. olivaceus sashimi sample. All detected K. septempunctata were of genotype ST3. This is the first study to identify K. septempunctata in both patients and food samples with epidemiological relevance in Korea, providing evidence that it is a pathogen that causes food poisoning. Also, this is the first study to confirm the presence of K. septempunctata genes in rectal swabs. Despite continuing suspected occurrences of Kudoa foodborne outbreaks, the rate of identification of K. septempunctata is very low. One reason for this is the limitation in obtaining stool and vomit samples for the diagnosis of Kudoa infection. We strongly suggest the inclusion of rectal swabs among the diagnostic specimens for Kudoa food poisoning.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2003년도 생물공학의 동향(XII)
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• pp.40-44
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• 2003

Soil-borne infectious disease including Pythium aphanidermatum and Rhizoctonia solani causes severe damage to plants, such as cucumber. This soil-borne infectious disease was not controlled effectively by chemical pesticide. Since these diseases spread through the soil, chemical agents are usually ineffective. Instead, biological control, including antagonistic microbe can be used as a preferred control method. An efficient method was developed to select an antagonistic strain to be used as a biological control agent strain. In this new method, surface tension reduction potential of an isolate was included in the ‘decision factor’ in addition to the other factors, such as growth rate, and pathogen inhibition rate. Considering these 3 decision factors by a statistical method, an isolate from soil was selected and was identified as Bacillus sp. GB16. In the pot test, this strain showed the best performance among the isolated strains. The lowest disease incidence rate and fastest seed growth was observed when Bacillus sp. GB16 was used. Therefore this strain was considered as plant growth promoting rhizobacteria (PGPR). The action of surface tension reducing component was deduced as the enhancement of wetting, spreading, and residing of antagonistic strain in the rhizosphere. This result showed that new selection method was significantly effective in selecting the best antagonistic strain for biological control of soil-borne infectious plant pathogen. The antifungal substances against P. aphanidermatum and R. solani were partially purified from the culture filtrates of Bacillus sp. GB16. In this study, lipopeptide possessing antifungal activity was isolated from Bacillus sp. GB16 cultures by various purification procedures and was identified as a surfactin-like lipopeptide based on the Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR), high performance liquid chromatography mass spectroscopy (HPLC-MS), and quadrupole time-of-flight (Q-TOF) ESI-MS/MS data. The lipopeptide, named GB16-BS, completely inhibited the growth of Pythium aphanidermatum, Rhizoctonia solani, Penicillium sp., and Botrytis cineria at concentrations of 10 and 50 mg/L, respectively. A novel method to prevent the foaming and to provide oxygen was developed. During the production of surface active agent, such as lipopeptide (surfactin), large amount of foam was produced by aeration. This resulted in the carryover of cells to the outside of the fermentor, which leads to the significant loss of cells. Instead of using cell-toxic antifoaming agents, low amount of hydrogen peroxide was added. Catalase produced by cells converted hydrogen peroxide into oxygen and water. Also addition of corn oil as an oxygen vector as well as antifoaming agent was attempted. In addition, Ca-stearate, a metal soap, was added to enhance the antifoam activity of com oil. These methods could prevent the foaming significantly and maintained high dissolved oxygen in spite of lower aeration and agitation. Using these methods, high cell density, could be achieved with increased lipopeptide productivity. In conclusion to produce an effective biological control agent for soil-borne infectious disease, following strategies were attempted i) effective screening of antagonist by including surface tension as an important decision factor ii) identification of antifungal compound produced from the isolated strain iii) novel oxygenation by $H_2O_2-catalase$ with vegetable oil for antifungal lipopeptide production.

• Journal of Microbiology and Biotechnology
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• 제15권6호
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• pp.1197-1206
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• 2005

Vibrio vulnificus is an opportunistic pathogen that causes a septicemia and expresses numerous virulence factors, in which luxS and smcR are genes encoding for components responsible for quorum-sensing regulation. In the present study, null mutants were constructed with lesions in each or both of these two genes from the V. vulnificus Vv$\Delta$Z strain, which is a lacZ$^{-}$ and chloramphenicol/streptomycin-resistant derivative of the wild-type ATCC29307 strain, and their phenotypes related to virulence were compared with those of the parental cells. $LD_{50}$ and histopathological findings of luxS-, smcR-, or luxS- smcR- deficient mutant were not different from those of the parent strain, a lacZ-deficient streptomycin-resistant strain in mice. However, time of death in mice was delayed, and numbers of bacteria survived in bloodstream after intraperitoneal injection in mice were decreased by mutation, especially luxS and smcR double mutant (VvSR$\Delta$ZSR). These phenomena were supported by increased serum sensitivity and delayed bacterial proliferation in both murine blood and iron-restricted medium. These results suggest that the luxS and luxR homologous genes in V. vulnificus could playa role in bacterial survival in host by enhancing proliferation and adjusting to changed environment.

• 한국양식학회지
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• 제10권2호
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• pp.171-178
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• 1997

Infectious pancreatic necrosis virus (IPNV)는 치어에 감염되어 치명적인 질병을 유발하는, 양식산업에 있어 중요한 어류 병원체이다. 본 연구에서는 IPNV를 신속, 정확하게 진단하는 방법을 개발하고자 IPNV의 항원성 단백질인 VP2 유전자 부분에서 선택한 primers를 이용하여 역전사-중합효소연쇄반응법(Reverse Transcription-Polymerase Chain Reaction, RT-PCR)을 실시하였다. RT-PCR 증폭법으로 순수분리도니 IPNV dsRNA 40 ng 정도의 적은 양도 확인 할 수 있었으며, IHNV와 같은 다른 어류 병원체의 게놈을 RT-PCR templates로 사용하였을 경우는 어떠한 PCR 산물도 검출되지 않는 특이성을 보였다. 특히 유전자의 분리없이 조직 그 자체를 대상으로 RT-PCR을 행하는 in situ RT-PCR 방법으로 IPNV가 감염된 넙치 (Paralichthy olivaceus) 치어의 조직에서 IPNV 감염을 신속하게 확인할 수 있었다. 따라서 RT-PCR 및 in situ RT-PCR 방법은 IPNV를 신속, 정확하게 진단하는데 활용될 수 있을 것으로 생각된다.