• Asian-Australasian Journal of Animal Sciences
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• 제29권3호
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• pp.315-320
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• 2016

Porcine beta-defensin-1 (PBD-1) gene plays an important role in the innate immunity of pigs. The peptide encoded by this gene is an antimicrobial peptide that has direct activity against a wide range of microbes. This peptide is involved in the co-creation of an antimicrobial barrier in the oral cavity of pigs. The objective of the present study was to detect polymorphisms, if any, in exon-1 and exon-2 regions of PBD-1 gene in Large White Yorkshire (LWY) and native Ankamali pigs of Kerala, India. Blood samples were collected from 100 pigs and genomic DNA was isolated using phenol chloroform method. The quantity of DNA was assessed in a spectrophotometer and quality by gel electrophoresis. Exon-1 and exon-2 regions of PBD-1 gene were amplified by polymerase chain reaction (PCR) and the products were subjected to single strand conformation polymorphism (SSCP) analysis. Subsequent silver staining of the polyacrylamide gels revealed three unique SSCP banding patterns in each of the two exons. The presence of single nucleotide polymorphisms (SNPs) was confirmed by nucleotide sequencing of the PCR products. A novel SNP was found in the 5'-UTR region of exon-1 and a SNP was detected in the mature peptide coding region of exon-2. In exon-1, the pooled population frequencies of GG, GT, and TT genotypes were 0.67, 0.30, and 0.03, respectively. GG genotype was predominant in both the breeds whereas TT genotype was not detected in LWY breed. Similarly, in exon-2, the pooled population frequencies of AA, AG, and GG genotypes were 0.50, 0.27, and 0.23, respectively. AA genotype was predominant in LWY pigs whereas GG genotype was predominant in native pigs. These results suggest that there exists a considerable genetic variation at PBD-1 locus and further association studies may help in development of a PCR based genotyping test to select pigs with better immunity.

• 수산해양교육연구
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• 제28권6호
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• pp.1640-1650
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• 2016

본 연구에서는 다양한 면역 유도제를 주사하여 갯지렁이의 면역을 유도시킨 후, 갯지렁이의 항균 펩타이드를 가장 많이 발현시킬 수 있는 최적의 면역 유도제를 선정하였으며, 선정된 면역 유도제로 면역을 유도한 갯지렁이를 분말화 하여 사료에 첨가하였을 때 양식 어류의 면역 활성을 증가시킬 수 있는지에 대한 여부를 조사하였다. 넙치와 조피볼락은 면역활성을 위한 갯지렁이 분말의 사료 첨가율이 서로 달랐으며, 넙치의 경우 0.1%의 사료 첨가율이 넙치의 라이소자임 활성, 혈청 내 코르티졸 농도뿐만 아니라 E. tarda에 대한 항병성에 가장 높은 효과를 보였다. 조피볼락은 0.5%의 사료 첨가율이 조피볼락의 라이소자임 활성을 증가시키고 혈청 내 코르티졸 농도를 감소시켰으며 S. iniae에 대한 항병성 또한 증가시켰다. 따라서 넙치와 조피볼락은 각각 면역 유도된 갯지렁이 분말이 0.1%와 0.5% 첨가된 사료를 급이하였을 때 면역 활성을 가장 많이 유도 할 수 있을 것으로 생각되지만, 반면 그 이상의 농도로 면역 유도된 갯지렁이 분말을 사료에 첨가하여 급이할 시 오히려 면역 활성에 부정적인 영향을 미칠 수 있을 것으로 생각된다. 이번 연구에서는 주간 8 갯지렁이 분말 첨가 사료를 급이한 것에 대한 양식 어류의 면역 활성을 검증 하였으며, 추후 연구에서는 갯지렁이 첨가사료의 급이 기간을 고려한 연구가 진행되어야 할 것으로 생각된다.

• Journal of Microbiology and Biotechnology
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• 제18권5호
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• pp.990-996
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• 2008

In a previous study, we found an antifungal effect on human pathogenic fungi by the cell-penetrating peptide Tat (47-58) derived from HIV-1. Tat (47-58) immediately entered into the fungal nucleus and affected some physiological changes on the intracellular condition. In this study, Tat (47-58) showed a broad spectrum of antibacterial activity against pathogenic bacteria including bacterial clinical isolates. To improve resistance against proteases for use in vivo, we synthesized an analog of Tat (47-58) by substituting the L-amino acid for the D-amino acid. The D-enantiomer of Tat (47-58) also exhibited a broad spectrum of antibacterial activity at almost the same level of L-Tat (47-58) concentration. Unlike L-Tat (47-58), D-Tat (47-58) showed a significant proteolytic resistance against all proteases tested and antimicrobial activities in the presence of trypsin. Moreover, D-Tat (47-58) inhibited MRSA infection in human HeLa cells whereas L-Tat (47-58) partially allowed MRSA infection, and the results were due to the proteolytic resistance of D-Tat (47-58).

• Journal of Microbiology and Biotechnology
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• 제32권6호
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• pp.816-823
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• 2022

The rapid spread of superbugs leads to the escalation of infectious diseases, which threatens public health. Endolysins derived from bacteriophages are spotlighted as promising alternative antibiotics against multi-drug resistant bacteria. In this study, we isolated and characterized the novel Salmonella typhimurium phage PBST08. Bioinformatics analysis of the PBST08 genome revealed putative endolysin ST01 with a lysozyme-like domain. Since the lytic activity of the purified ST01 was minor, probably owing to the outer membrane, which blocks accessibility to peptidoglycan, antimicrobial peptide cecropin A (CecA) was fused to the N-terminus of ST01 to disrupt the outer membrane. The resulting CecA::ST01 has been shown to have increased bactericidal activity against gram-negative pathogens including Pseudomonas aeruginosa, Klebsiella pneumoniae, Acinetobacter baumannii, Escherichia coli, and Enterobacter cloacae and the most affected target was A. baumannii. In the presence of 0.25 µM CecA::ST01, A. baumannii ATCC 17978 strain was completely killed and CCARM 12026 strain was wiped out by 0.5 µM CecA::ST01, which is a clinical isolate of A. baumannii and resistant to multiple drugs including carbapenem. Moreover, the larvae of Galleria mellonella could be rescued up to 58% or 49% by the administration of CecA::ST01 upon infection by A. baumannii 17978 or CCARM 12026 strain. Finally, the antibacterial activity of CecA::ST01 was verified using 31 strains of five gram-negative pathogens by evaluation of minimal inhibitory concentration. Thus, the results indicate that a fusion of antimicrobial peptide to endolysin can enhance antibacterial activity and the spectrum of endolysin where multi-drug resistant gram-negative pathogens can be efficiently controlled.

• IMMUNE NETWORK
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• 제20권3호
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• pp.25.1-25.13
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• 2020

Acinetobacter baumannii is known for its multidrug antibiotic resistance. New approaches to treating drug-resistant bacterial infections are urgently required. Cathelicidin-related antimicrobial peptide (CRAMP) is a murine antimicrobial peptide that exerts diverse immune functions, including both direct bacterial cell killing and immunomodulatory effects. In this study, we sought to identify the role of CRAMP in the host immune response to multidrug-resistant Acinetobacter baumannii. Wild-type (WT) and CRAMP knockout mice were infected intranasally with the bacteria. CRAMP^-/- mice exhibited increased bacterial colony-forming units (CFUs) in bronchoalveolar lavage (BAL) fluid after A. baumannii infection compared to WT mice. The loss of CRAMP expression resulted in a significant decrease in the recruitment of immune cells, primarily neutrophils. The levels of IL-6 and CXCL1 were lower, whereas the levels of IL-10 were significantly higher in the BAL fluid of CRAMP^-/- mice compared to WT mice 1 day after infection. In an in vitro assay using thioglycollate-induced peritoneal neutrophils, the ability of bacterial phagocytosis and killing was impaired in CRAMP^-/- neutrophils compared to the WT cells. CRAMP was also essential for the production of cytokines and chemokines in response to A. baumannii in neutrophils. In addition, the A. baumannii-induced inhibitor of κB-α degradation and phosphorylation of p38 MAPK were impaired in CRAMP^-/- neutrophils, whereas ERK and JNK phosphorylation was upregulated. Our results indicate that CRAMP plays an important role in the host defense against pulmonary infection with A. baumannii by promoting the antibacterial activity of neutrophils and regulating the innate immune responses.

• Journal of Microbiology and Biotechnology
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• 제24권2호
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• pp.160-167
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• 2014

Oligopeptidase B (OpdB) is a serine peptidase widespread among bacteria and protozoa that has emerged as a virulence factor despite its function has not yet been precisely established. By using an OpdB-overexpressing Escherichia coli strain, we found that the overexpressed peptidase makes the bacterial cells specifically less susceptible to several proline-rich antimicrobial peptides known to penetrate into the bacterial cytosol, and that its level of activity directly correlates with the degree of resistance. We established that E. coli OpdB can efficiently hydrolyze in vitro cationic antimicrobial peptides up to 30 residues in length, even though they contained several prolines, shortening them to inactive fragments. Two consecutive basic residues are a preferred cleavage site for the peptidase. In the case of a single basic residue, there is no cleavage if proline residues are present in the $P_1$ and $P_2$ positions. These results also indicate that cytosolic peptidases may cause resistance to antimicrobial peptides that have an intracellular mechanism of action, such as the proline-rich peptides, and may contribute to define the substrate specificity of the E. coli OpdB.

• The Plant Pathology Journal
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• 제33권1호
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• pp.87-94
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• 2017

Citrus canker disease decreases the fruit quality and yield significantly, furthermore, emerging of streptomycin-resistant pathogens threatens the citrus industry seriously because of a lack of proper control agents. Small synthetic antimicrobial peptides (AMPs) could be a promising alternative. Fourteen hexapeptides were selected by using positional scanning of synthetic peptide combinatorial libraries. Each hexapeptide showed different antimicrobial spectrum against Bacillus, Pseudomonas, Xanthomonas, and Candida species. Intriguingly, BHC10 showed bactericidal activity exclusively on Xanthomonas citri subsp. citri (Xcc), while BHC7 was none-active exclusively against two Pseudomonas spp. at concentration of $100{\mu}g/ml$ suggesting potential selectivity constrained in hexapeptide frame. Three hexapeptides, BHC02, 06 and 11, showed bactericidal activities against various Xcc strains at concentration of $10{\mu}g/ml$. When they were co-infiltrated with pathogens into citrus leaves the disease progress was suppressed significantly. Further study would be needed to confirm the actual disease control capacity of the selected hexapeptides.

• BMB Reports
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• 제38권5호
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• pp.507-516
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• 2005

Antimicrobial peptides (AMPs) have been isolated and characterized from tissues and organisms representing virtually every kingdom and phylum. Their amino acid composition, amphipathicity, cationic charge, and size allow them to attach to and insert into membrane bilayers to form pores by 'barrel-stave', 'carpet' or 'toroidal-pore' mechanisms. Although these models are helpful for defining mechanisms of AMP activity, their relevance to resolving how peptides damage and kill microorganisms still needs to be clarified. Moreover, many AMPs employ sophisticated and dynamic mechanisms of action to carry out their likely roles in antimicrobial host defense. Recently, it has been speculated that transmembrane pore formation is not the only mechanism of microbial killing by AMPs. In fact, several observations suggest that translocated AMPs can alter cytoplasmic membrane septum formation, reduce cell-wall, nucleic acid, and protein synthesis, and inhibit enzymatic activity. In this review, we present the structures of several AMPs as well as models of how AMPs induce pore formation. AMPs have received special attention as a possible alternative way to combat antibiotic-resistant bacterial strains. It may be possible to design synthetic AMPs with enhanced activity for microbial cells, especially those with antibiotic resistance, as well as synergistic effects with conventional antibiotic agents that lack cytotoxic or hemolytic activity.

• 농업과학연구
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• 제25권1호
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• pp.52-67
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• 1998

본 연구는 포유동물의 젖에 함유되어 있는 lactoferrin(LF)의 생리적 특성을 밝혀 기능성 식품 특히 항균작용을 이용한 식품제조업에의 이용을 위한 기초자료를 얻고자 실시하였다. 따라서 젖소의 초유로부터 lactoferrin을 분리 정제하여, 소화부위에 따른 lactoferrin의 항균활성을 분석하고자 pepsin, trypsin 및 chymotrypsin으로 분해하여 lactoferrin의 항균력을 측정하고, gel-filtration으로 분리 정제된 각각의 fraction별로 단백질을 정량하여 Escherichia coli와 Staphylococcus aureus에 접종하여 항균효과를 지니는 각 효소별 fraction의 분자량과 peptide fragment를 검토하였다. 1. 젖소의 초유로부터 분리 정제된 lactoferrin(LF)을 단백질 분해 효소인 pepsin, trypsin 및 chymotrypsin으로 분해한 결과 bovine lactoferrin은 SDS-PAGE를 수행하여 band를 확인할 수 있었다. pepsin으로 분해된 lactoferrin은 분자량 14KDa까지에서도 band를 확인할 수가 없었으며, trypsin과 chymotrypsin으로 분해한 lactoferrin은 분해되지 않은 lactoferrin이 존재함을 나타내고, 33KDa에서도 band를 확인할 수 있었다. 2. Sephadex G-50 column을 사용하여 bovine lactoferrin를 효과적으로 정제하였다. Sephadex G-50 column chromatography를 수행 한 결과 bovine lactoferrin은 Tris-HCl사이에서 용출되었으며, pepsin, trypsin 및 chymotrypsin으로 분해한 lactoferrin은 각각 2, 3, 2 개의 peak를 보였고, HPLC 분석결과 첫번째 peak는 주로 분해되지 않은 lactoferrin 수용체가 존재하는 것으로 확인되었으며, trypsin과 chymotrypsin처리에서 항균효과도 유사점을 관찰할 수 있었다. 3. 효소처리한 lactoferrin의 항균효과를 알아보기 위하여 Escherichia coli와 Staphylococcus aureus를 접종하여 항균활성을 비교하였다. 그 결과 각 효소에 대하여 pepsin으로 처리한 lactoferrin을 접종한 시험구가 대조구에 비하여 낮은 생장율을 보여 현저한 항균활성을 지님을 알 수 있었다. 그리고 trypsin과 chymotrysin에 의한 분해물도 미생물 배양 8시간까지는 효소 처리전 bovine lactoferrin보다는 항균활성을 나타냄을 알 수 있었다. 4. Sephadex G-50 column을 사용하여 분리 정제된 bovine lactoferrin fraction별로 SDS-PAGE를 실시한 결과 lactoferrin fraction의 경우는 chromatography 수행 결과와 비교하여, pepsin과 chymotrypsin 분해물은 저분자량임을 알 수 있었고, trypsin에 의한 lactoferrin만이 단일 band를 보임으로서 단백질 분해의 특징을 볼 수 있었다.

• Journal of Microbiology and Biotechnology
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• 제25권12호
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• pp.2082-2089
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• 2015

Avian beta-defensin 9 (AvBD9) is a small cationic peptide consisting of 41 amino acids that plays a crucial rule in innate immunity and acquired immunity in chickens. Owing to its wide antibacterial spectrum, lack of a residue, and failure to induce bacterial drug resistance, AvBD9 is expected to become a substitute for conventional antibiotics in the livestock and poultry industries. Using the preferred codon of Pichia pastoris, the mature AvBD9 peptide was designed and synthesized, based on the sequence from GenBank. The P. pastoris constitutive expression vector pGHKα was used to construct a pGHKα-AvBD9 recombinant plasmid. Restriction enzyme digestion was performed using SacI and BglII to remove the ampicillin resistance gene, and the plasmid was electrotransformed into P. pastoris GS115. High-expression strains with G418 resistance were screened, and the culture supernatant was analyzed by Tricine-SDS-PAGE and western blot assay to identify target bands of about 6 kDa. A concentrate of the supernatant containing AvBD9 was used for determination of antimicrobial activity. The supernatant concentrate was effective against Escherichia coli, Salmonella paratyphi, Salmonella pullorum, Pseudomonas aeruginosa, Enterococcus faecalis, and Enterobacter cloacae. The fermentation product of P. pastoris carrying the recombinant AvBD9 plasmid was adjusted to 1.0 × 10⁸ CFU/ml and added to the drinking water of white feather broilers at different concentrations. The daily average weight gain and immune organ indices in broilers older than 7 days were significantly improved by the AvBD9 treatment.