• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.12
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• pp.6208-6214
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• 2012

The most essential but missing components to understand and use toxic substances from marine microalgae are developing the fast, easy and economical determining technology for detecting it. In this paper we produced the antibodies against saxitoxin (STX). Mariculture keyhole limpet hemocyanin (mcKLH) and ovalbumin (OVA) were used as carrier proteins. mcKLH-STX conjugates were injected into the peritonial cavity of BALB/c mouse for immunization. After bleeding from mouse, anti-STX antiserum was isolated. Indirect enzyme-linked immunosorbent assays (ELISA) was performed to determine antiserum titer using the microtiter plate coated with free STX and OVA-STX. A goat anti-mouse IgG-phosphatase conjugate was used as secondary antibody to enable chromogenic reaction. Reactions of anti-STX antiserum were very specific on the OVA-STX and free STX. Sensitivity of anti-STX antiserum on STX was very high and STX detection limit was to be 64.9 ng/kg for indirect ELISA.

• Journal of Microbiology and Biotechnology
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• v.31 no.5
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• pp.710-716
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• 2021

A risk analysis of Shiga toxin (Stx)-encoding bacteriophage was carried out by confirming the transduction phage to non-Stx-producing Escherichia coli (STEC) and subsequent expression of the Shiga toxin genes. The virulence factor stx1 was identified in five phages, and both stx1 and stx2 were found in four phages from a total of 19 phage isolates with seven non-O157 STEC strains. The four phages, designated as ϕNOEC41, ϕNOEC46, ϕNOEC47, and ϕNOEC49, belonged morphologically to the Myoviridae family. The stabilities of these phages to temperature, pH, ethanol, and NaClO were high with some variabilities among the phages. The infection of five non-STEC strains by nine Stx-encoding phages occurred at a rate of approximately 40%. Non-STEC strains were transduced by Stx-encoding phage to become lysogenic strains, and seven convertant strains had stx1 and/or stx2 genes. Only the stx1 gene was transferred to the receptor strains without any deletion. Gene expression of a convertant having both stx1 and stx2 genes was confirmed to be up to 32 times higher for Stx1 in 6% NaCl osmotic media and twice for Stx2 in 4% NaCl media, compared with expression in low-salt environments. Therefore, a new risk might arise from the transfer of pathogenic genes from Stx-encoding phages to otherwise harmless hosts. Without adequate sterilization of food exposed to various environments, there is a possibility that the toxicity of the phages might increase.

• Korean Journal of Veterinary Service
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• v.46 no.4
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• pp.325-334
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• 2023

Edema disease (ED) in pigs is enterotoxemia caused by Shiga toxin type 2e (Stx2e)-producing Escherichia coli (STEC) and frequently occurs in young piglets. Therefore, ED causes enormous economic losses in pig farms. In this study, a modified Stx2e (mStx2e) antigen was expressed and purified using commercial E. coli expression system. Monoclonal antibody was serviced by Ynto Ab Inc., using Phage Display Technique. Anti-Stx2e antibodies in piglets were measured by indirect ELISA using mStx2e antigens. Naive Stx2e in piglets were detected by Sandwich ELISA using Stx2e-monoclonal antibodies and commercial Stx2e-polyclonal antibodies. Among 3,480 piglets, anti-Stx2e antibodies were observed in 2,573 piglets. The 49.4% among 830 piglet serum samples possessed 0.625 ㎍/mL or more of Stx2e proteins. The 18.3% of 830 sera had 0.313 ㎍/mL of Stx2e proteins. The 32.3% of 830 samples held 0.156 ㎍/mL or less of Stx2e proteins. These results show that indirect ELISA using mStx2e antigen and Sandwich ELISA using Stx2e-monoclonal and polyclonal antibodies can be useful to detect ED in piglets.

• Journal of Food Hygiene and Safety
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• v.35 no.6
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• pp.521-534
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• 2020

Paralytic shellfish poisoning (PSP) occurs when saxitoxin (STX), which is produced by harmful algae (dinoflagellates) and then accumulated in bivalve shellfish by filter-feeding, is consumed by humans. With recent advances in analysis technology, it has been reported that dinoflagellates also produce a variety of analogues such as the gonyautoxin (GTX) group and the N-sulfo-carbamoyl toxin (C toxin) group, in addition to STX. Accordingly, CODEX and the EFSA are stepping forward to manage STX and analogues as STX groups requiring safety management. In Korea, the occurrence of dinoflagellates producing STX analogues has already been reported, and contamination of analogues (GTX group, C toxin group) in live mussels has also been reported. In this study, in order to provide the basis for systematic monitoring and safety management of STX and analogues, their physicochemical characteristics, occurrence of dinoflagellates, toxicity and toxic equivalency factor, analytical method and occurrence were widely reviewed. This review is expected to contribute to strengthening the safety management of STX and its analogues.

• Korean Journal of Veterinary Service
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• v.39 no.2
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• pp.87-92
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• 2016

Porcine edema disease (ED) is a communicable disease of pigs caused by infection with Shiga toxin (Stx)-producing Escherichia coli (STEC) which expresses F18 fimbriae and/or Stx type 2e (Stx2e). While STEC causes a severe illness including hemorrhagic colitis and hemolytic-uremic syndrome in humans, it induces damage to the vascular endothelium, which results in edema, hemorrhage, and microthrombosis, leading in high mortality in pigs. In the present study, we cultured Stx2e-producing E. coli field isolates from conventional pig farms that experienced sudden deaths previously with symptoms similar to porcine edema disease, which were further investigated with Shiga toxin profiles. A total of 43 strains were identified from the collected samples by F18 or Stx2e specific PCR. Based on the PCR, 42 isolates out of 43 isolates were proved to carry one of F18 or Stx2e genes and 14 isolates to carry both F18 and Stx2e genes. All of the 30 isolates that harbored Stx2e gene induced the cytopathic effect (CPE) in vero cells and especially, the isolate 150229 produced the highest level of Shiga toxin. Therefore, we identified the virulence genes (F18 and Stx2e) and demonstrated Shiga toxin-producing abilities from porcine edema disease causing E. coli filed isolates. These results suggested that one of the isolates could be a vaccine antigen candidate against STEC through further investigating to elicit an immune response.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.1
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• pp.80-86
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• 2010

This paper describes the development result of S-band Transmitter of STSAT-3 by satellite research center(SaTReC), KAIST. STSAT-3 has two kinds of communication channels, S- band for Telemetry & Command and X-band for mission payload. S-band Transmiiter(STX) consist of modulator, frequency synthesizer, power amp and DC/DC converter. The modulation scheme of STX is FSK(Frequency Shift Keying). The interface between spacecraft OBC and STX is RS-422. The STX is based on modular design. The RF output power of STX is 1.5W(31.7dBm) and BER of STX is under 1E-5. The Test of STX is completed successfully such as functional Test and environmental(vibration, thermal vacuum) Test.

• Korean Journal of Veterinary Research
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• v.44 no.2
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• pp.251-257
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• 2004

This study was designed to determine optimal condition for expression of cloned Shigatoxin2e(Stx2e) gene from transformed E. coli PED18, to compare the cytotoxicity titer between cloned Stx2e and Stx2e from original strain, and to confirm of receptor binding affinity of Stx2e for use of development of receptor binding ELISA to detect of Stx2e. The optimum composition of medium for expression of Stx2e gene in E.coli host-vector system was definded as the medium containing 0.5% glucose and 0.5 mM IPTG. The cytotoxicity titer of expressed Stx2e for Vero cell was 1000 fold higher than that of Stx2e from original strain AY93258. The binding affinity of Stx2e to receptor globotetraosyl ceramide($Gb_4$) was confirmed by immunobloting.

• BMB Reports
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• v.42 no.5
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• pp.310-314
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• 2009

Globotriaosylceramide (Gb3) and globotetraosylceramide (Gb4) are the proposed functional receptors for Shiga toxin (Stx). To elucidate the effect of Gb3 content on Stx-induced cytotoxicity in HeLa cells, we cloned HeLa cells and determined the correlation between glycolipids content and Stx-induced cytotoxicity. The 29 HeLa cell clone (HLCC) lines used showed a wide range of sensitivity to Stx, compared to Gb3-rich cells which were more sensitive, showing as little as 20% viability to 100 pg/ml Stx. In contrast, Gb3-deficient cells proved resistant as they were more than 80% viable to 100 ng/ml Stx. Gb3 content in the HLCC lines corresponded with Stxs-induced cytotoxicity as well as Gb3 synthase expression, but no correlation with Gb4 content was noted. These data show that Gb3 content, which is regulated by the expression of Gb3 synthase, determines the sensitivity of HeLa cells toward Stx.

• Journal of the Society of Naval Architects of Korea
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• v.51 no.2
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• pp.130-137
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• 2014

As one of the largest shipbuilding company in the world, STX Offshore & Shipbuilding currently developed an inventory managing system for steel-plates, which is applied to their steel stock yard. In a traditional way to manage steel yard, almost every work has been done by manually. The manual steel-plate piling process caused some problems such as process delay due to piling errors and the uncertainty of work plan due to lack of information. To solve these problems, we developed an integrated inventory managing system based on real-time crane tracking system which automatically updates steel-plates' piling status. We built the integrated steel-plate database, developed several programs including steel-plate input program, real-time steel-plate monitoring program and steel-yard management program, and constructed hardware system for tracking magnetic cranes. As a result, a supervisor of steel-yard can manage the inventory of steel-plates efficiently and furthermore plan an efficient piling schedule and crane working schedule.

• Journal of Food Hygiene and Safety
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• v.29 no.4
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• pp.316-321
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• 2014

The aim of study was to investigate the virulence profile of Escherichia coli O157:H7 bacteriophages isolated from sewage and livestock stools. Among 23 E. coli O157:H7 bacteriophages, 14 strains were isolated from sewage and 9 were from animal stools collected from 10 livestock farms in Korea. For each bacteriophage DNA sample, the presence of stx1, stx2, eae, aafII, ial, elt, estI, estII, astA, afa, and cnf was examined by polymerase chain reaction. The detection rate of eae, stx2, estI, astA, and ial was 100%, 69.6%, 13.0%, 13.0%, 8.7%, respectively. While all E. coli O157:H7 bacteriophages isolated from stools carried eae+stx2, stx2+eae, eae+astA, eae, stx2+eae+estI, eae+estI, stx2+eae+ial, and eae+ial were observed in bacteriophages isolated from sewage. As several plasmid-carrying virulence factors (estI, astA, and ial) were found in E. coli O157:H7 bacteriophages obtained from sewage and stools, the microbial safety of bacteriophages should be investigated in further study.