• 한국축산식품학회지
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• 제37권1호
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• pp.134-138
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• 2017

Salmonella enterica infects a broad range of host animals, and zoonostic infection threatens both public health and the livestock and meat processing industries. Many antimicrobials have been developed to target Salmonella envelope that performs essential bacterial functions; however, there are very few analytical methods that can be used to validate the efficacy of these antimicrobials. In this study, to develop a potential biosensor for Salmonella envelope stress, we examined the transcription of the S. enterica serovar typhimurium spy gene, the ortholog of which in Escherichia coli encodes Spy (${\underline{s}}pheroplast$ ${\underline{p}}rotein$ ${\underline{y}}$). Spy is a chaperone protein expressed and localized in the periplasm of E. coli during spheroplast formation, or by exposure to protein denaturing conditions. spy expression in S. typhimurium was examined by constructing a spy-gfp transcriptional fusion. S. typhimurium spy transcription was strongly induced during spheroplast formation, and also when exposed to membrane-disrupting agents, including ethanol and the antimicrobial peptide polymyxin B. Moreover, spy induction required the activity of regulator proteins BaeR and CpxR, which are part of the major envelope stress response systems BaeS/BaeR and CpxA/CpxR, respectively. Results suggest that monitoring spy transcription may be useful to determine whether a molecule particularly cause envelope stress in Salmonella.

• 미생물학회지
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• 제54권2호
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• pp.155-157
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• 2018

Salmonella enterica subsp. enterica serovar Thompson strain MFDS1004024 는 2014 년 한국에서 발생한 식중독 사고의 게맛살에서 분리되었다. 본 연구에서는 4,742,942 bp 의 크기와 약 52%의 G + C 함량을 가진 MFDS1004024 균주의 완전한 유전체 염기서열을 분석하였다. 이 유전체에는 4,373 개의 코딩 서열, 22 개의 리보솜 RNA 유전자 및 84 개의 전사 RNA 유전자가 존재한다. 또한 유전체 분석 결과를 통해 살모넬라 감염과 베타락탐계 항생제 내성에 관련이 있는 유전자를 발견하였다.

• Journal of Microbiology and Biotechnology
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• 제29권6호
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• pp.962-972
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• 2019

Non-typhoidal Salmonella (NTS) is one of the most frequent causes of bacterial foodborne illnesses. Considering that the main reservoir of NTS is the intestinal tract of livestock, foods of animal origin are regarded as the main vehicles of Salmonella infection. In particular, poultry colonized with Salmonella Typhimurium (S. Typhimurium), a dominant serotype responsible for human infections, do not exhibit overt signs and symptoms, thereby posing a potential health risk to humans. In this study, comparative genomics approaches were applied to two S. Typhimurium strains, ST1539 and ST1120, isolated from a duck slaughterhouse and a pig farm, respectively, to characterize their virulence and antimicrobial resistance-associated genomic determinants. ST1539 containing a chromosome (4,905,039 bp; 4,403 CDSs) and a plasmid (93,876 bp; 96 CDSs) was phylogenetically distinct from other S. Typhimurium strains such as ST1120 and LT2. Compared to the ST1120 genome (previously deposited in GenBank; CP021909.1 and CP021910.1), ST1539 possesses more virulence determinants, including ST64B prophage, plasmid spv operon encoding virulence factors, genes encoding SseJ effector, Rck invasin, and biofilm-forming factors (bcf operon and pefAB). In accordance with the in silico prediction, ST1539 exhibited higher cytotoxicity against epithelial cells, better survival inside macrophage cells, and faster mice-killing activity than ST1120. However, ST1539 showed less resistance against antibiotics than ST1120, which may be attributed to the multiple resistanceassociated genes in the ST1120 chromosome. The accumulation of comparative genomics data on S. Typhimurium isolates from livestock would enrich our understanding of strategies Salmonella employs to adapt to diverse host animals.

• 한국동물위생학회지
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• 제23권4호
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• pp.349-360
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• 2000

An epidemiological survey was conducted to investigate fowl typhoid outbreaks in Kyungnam province of Korea. The causative agent, salmonella gallinarum was isolated from 68 chicken samples of tentatively diagnosed fowl typhoid cases occurred during the period from January 1996 to September 1999. Comparative studies were also carried out to evaluate the diagnostic methods for detection of S gallinam The results obtained were as follows; 1. Of the 68 cases of tentatively diagnosed fowl typhoid, 56 (82%) cases were determined as fowl typhoid by biochemical test and pathological findings. The other 12 (18%) cases were determined as paratyphoid. 2. Fowl typhoid outbreaks occur continuously all seasons in the year, however the incidence was remarkably increased from May to September. 3. The frequency of incidence of fowl typhoid in terms of regional distribution was relatively high in egg-laying hens facilities, and the mode of transmission is likely to be either egg-to-egg or lateral transfer by wild birds or rats. 4. All of 18 isolates from 56 cases were identified as S gallinarum by biochemical and serological test. 5. Antimicrobial drug susceptibility test against 18 isolates showed that the isolates were highly susceptible to ASH, CZ, CF and GM (above 90%), whereas those strains were 100% resistant to EM, NA and PC. 6. S gallinarum rfbS gene was targeted to be amplified by PCR for comparative detection of S gallinarum in the experimentally infected chickens. The amplified 720bp DNA fragment, which is specific in D serogroup strains of S enterica subspecies was confirmed by agarose gel electrophoresis. 7. A comparison made between fecal culture and PCR-method revealed that later-method was relatively higher in detection rate than that of former method for S gallinarum. 8. Comparison of currently applied methods, rapid serum agglutination test (RST) and microplate agglutination test (MAT), with experimentally infected chickens were made to evaluate sensitivity of detection by neutralizing antibody titration. Both methods detected neutralizing antibodies from the challenged chickens of 5 day post infection. However, positive reactions were determined after 7 and 9 days post infection by MAT and RST, respectively.

• 한국동물위생학회지
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• 제31권3호
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• pp.305-313
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• 2008

The present study was conducted to investigate the epidemiological characteristics such as isolation rate and antimicrobial drug susceptibility of etiological agents. The specimens (stool or intestine) were collected from 319 calves with clinical diarrhea from 195 farms in Gyeongnam south area (Gosung, Tongyung, Hadong) from June 2005 to August 2006. The isolation rate of Salmonella spp was higher in summer (8.4%) than in winter (4.8%) and the average was 7.2% (23/319 head). Some of Salmonella spp isolated were resistant to penicillin, oxytetracycline, tetracycline, and cephalexin (>90%), but some of them were susceptible to norfloxacin, ciprofloxacin, sulfamethoxazole/trimethoprim and amikacin(>30%). There was no statistical difference in the isolation rate of Eimeria spp between summer(48.9%) and winter(42.3%). For the evaluation of infection level of Eimeria spp oocyst per gram of feces (OPG) was examined, and severe, moderate and light infection level were 11.9%, 12.5% and 22.3%, respectively. In the isolation rates of Eimeria spp the calves under 19 days was lowerthan those over 60 days, but there was not different among herd size.

• 한국동물위생학회지
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• 제32권1호
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• pp.77-82
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• 2009

Salmonella (S.) Typhimurium infection in pigs is a major source of human foodborne salmonellosis. Recently, the swine industry in Korea has been suffered from salmonellosis causing severe economic loss to farms. Organic acids have antibacterial activity which prevents bacteria from multiplying by reducing the pH in the gastrointestinal tract. The aim of the present study is to evaluate whether $Salstop^{(R)}$ mixed with organic acids is able to have influence on growth performance and whether it prevents against S. Typhimurium in weaning pigs. Four experimental treatments were examined: general diet added with 0.3% of $Salstop^{(R)}$ after S. Typhimurium ($1.0{\times}10^{10}CFU/ml$) challenge, group A; commercial feed after Salmonella ($1.0{\times}10^{10}CFU/ml$) challenge, group B; commercial feed and $Salstop^{(R)}$, group C; commercial feed, Group D. At the end of the study, no significant differences in daily body weight gain and feed intake were observed between groups treated with $Salstop^{(R)}$ and groups treated without, whereas feed conversion ratio (FCR) tended to be improved in groups treated with $Salstop^{(R)}$ between days 1 to 14. Serological and microbiological evolution of the infection were examined by ELISA and microbiological culture from serums and fecal samples, respectively. In groups that challenged by S. Typhimuriums, the group without $Salstop^{(R)}$ showed higher prevalence and bacterial shedding compared to the groups treated with $Salstop^{(R)}$. Our results suggest that the administration of $Salstop^{(R)}$ could be used to promote feed efficiency and to reduce the prevalence of salmonellosis in weaners.

• 생명과학회지
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• 제18권11호
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• pp.1507-1512
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• 2008

오랜 기간 동안의 연구에도 불구하고 사람에 특이적으로 장티푸스를 유발하는 S. typhi는 실험동물을 대상으로 하는 감염모델이 확립되어 있지 않기 때문에 S. typhi의 병원성 유발기작에 관한 정보는 부족하다. S. typhi Ty2 균주는 최소배지에서 시스테인의 영양요구성을 지닌다. 본 연구에서는 시스테인 영양요구성이, S. typhi Ty2 균주가 실험동물에서 균체형성을 하는데 어떤 영향을 미치는지를 조사하기 위해 시스테인 영양요구성을 상보할 수 있는 유전자를 찾고자 하였다. S. typhimurium의 genomic library로 형질전환된 S. typhi 균들 중 시스테인을 함유하지 않은 최소배지에서 생육을 하는 3개의 형질전환 균주를 선별하였으며, 이들 중 2개는 S. typhi의 시스테인 영양요구성을 아주 약하게 상보하였고 하나는 명확하게 시스테인의 영양요구성을 상보하였다. 이 클론에 포함되어져 있는 3개의 ORF의 시스테인 영양요구성을 분석한 결과, STM1490을 가진 클론이 S. typhi의 시스테인 영양요구성을 상보하였다. 비록 S. typhi에도 STM1490에 해당하는 유전자가 존재하지만 S. typhimurium의 STM1490에 해당하는 ORF와 비교하였을 때 2개의 아미노산 잔기가 서로 달랐다. 이들의 차이가 시스테인 영양요구성을 보이는 것은 아닌지 확인하기 위해 Overlapping PCR을 통해 S. typhimurium의 STM1490 아미노산(H229Y, C246W)을 치환하였다. 아미노산을 바꾼 돌연변이체도 역시 시스테인 영양요구성을 상보할 수 있어서 아미노산의 차이는 아닌 것을 확인되었으므로 그 외의 다른 인자들이 영양요구성에 관여하는 것으로 추정되었고 후속연구에서 그인자를 찾을 수 있을 것으로 생각된다.

• 생명과학회지
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• 제17권1호
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• pp.31-38
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• 2007

사람의 장티푸스 연구는 생쥐에 감염되는 Salmonella typhimurium를 모델로 연구되고 있으며, 생쥐에 있어서 S. typhimurium의 감염은 이자세포의 증식반응을 감소시키는 것으로 알려져 있다. S. typhimurium lipid A의 처리가 T세포 mitogen에 의한 이자 세포의 증식에 어떤 영향을 주는 가를 in vitro와 ex vivo조건에서 알아 보았다. Lipid A 단독 처리는 이자 세포의 증식을 보였으나, lipid A 처리 후 T 세포 mitogen인 concanavalin A (Con A)와 phytohemagglutinin (PHA)에 의한 in vitro와 ex vivo 조건에서의 이차 처리는 오히려 세포증식이 억제되었다. Lipid A를 주사한 생쥐로부터 분리한 이자 세포에서 대식세포를 제거하였을 조건에서는 T 세포 mitogen에 의한 증식 효과가 유지되었으나 대식세포를 제거하지 않았을 경우에는 T세포 mitogen에 의한 증식 효과가 억제되었다. Lipid A를 주사한 생쥐에서 얻은 대식세포를 포함한 이자세포의 숫자를 증가하면서 Lipid A를 주사하지 않은 생쥐에서 얻은 이자세포와 혼합 배양하였을 때 Lipid A를 주사한 생쥐에서 얻은 대식세포를 포함한 이자세포의 숫자가 높을수록 Con A와 PHA에 의한 증식억제가 높게 측정되었다. 이러한 결과는 Con A와 PHA의 이자세포 증식 기능이 lipid A의 전처리에 의해 활성화된 대식세포의 직접적인 접촉 작용으로 억제된 것으로 생각된다. 본 연구의 결과를 바탕으로 억제에 관여하는 대식세포 표면분자를 밝히는 것이 사람의 장티푸스 연구에 도움이 되리라 생각된다.

• 한국축산식품학회지
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• 제30권1호
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• pp.62-65
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• 2010

Salmonellosis is one of the most important wasting diseases that leads to economic damage in the swine industry. Many risk factors have been reported to increase the spread of Salmonella infection; therefore, it is important to understand how to treat the risk factors of Salmonella to effectively prevent salmonellosis in commercial pig farms. To accomplish this, we conducted a study to determine if the seasons and porcine production stages affected the serological response to Salmonella in Korea. A total of 1,592 serum samples submitted to the School of Veterinary Medicine of Kangwon National University between Jan. 2001 and Dec. 2004 from commercial farms were tested by ELISA. The overall apparent seroprevalence of salmonellosis was 38.1% (95% CI, 38.0-38.2), while the prevalence of Salmonella according to seasons and production stages ranged from 17.9% to 62.8% for the former (24.6% in spring, 17.9% in summer, 38.5% in autumn, and 62.8% in winter) and from 16.1% to 68.3% for the latter (17.9% in suckling pigs, 16.1% in weaning pigs, 37.50% in growers, 41.9% in finishers, 48.0% in gilts, and 68.3% in sows). In this study of seroprevalence by production stage, most pigs were naturally infected by Salmonella during the weaning stage. Also, seroprevalences were found to have a seasonal pattern in which most pigs were infected in autumn to winter.

• Asian-Australasian Journal of Animal Sciences
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• 제25권7호
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• pp.1038-1044
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• 2012

In the present study, the impact of Salmonella Typhimurium on cell-mediated immunity (CMI) was investigated in 5 week-old immuno divergent broiler lines selected for the high and low response to phytohemagglutinin-P. The immune response was assessed in peripheral-blood mononuclear cells (PBMCs) induced with Salmonella Typhimurium at different time intervals (0 h, 0.5 h, 2 h, 4 h, 6 h, 12 h and 24 h). The differential mRNA expression patterns of IFN-${\gamma}$, IL-2 and iNOS were evaluated by quantitative real time PCR. In-vitro production of nitric oxide (NO) was also estimated in the culture supernatant and correlated with iNOS mRNA expression. Present study showed higher production of NO in the high cell-mediated line (HCMI) as compared to the low cell-mediated line (LCMI) upon stimulation with Salmonella Typhimurium. Correspondingly, higher mRNA expression of iNOS and IFN-${\gamma}$ were observed in high response birds (HCMI); but IL-2 was down regulated in this line compared to the low response birds (LCMI). Significantly (p<0.05) higher expression of iNOS, IFN-${\gamma}$ and higher production of NO in high line indicated that the selection for PHA-P response might be employed for increasing the immune competence against Salmonella Typhimurium in chicken flocks.