• Food Science and Biotechnology
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• v.16 no.4
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• pp.515-519
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• 2007

Rapid immunochromatographic assay (ICA) kits were developed using flagella-specific monoclonal antibodies (MAbs) and rabbit polyclonal antibodies for screening Listeria spp. in food. The establishment of different formats, MAb 2B1 as capture antibody and MAb 7A3 or rabbit polyclonal antibodies as detector antibody, was compared. The 2 formats of the ICA kit were shown to have specific reactions with Listeria and no cross-reactivity with any of the non-Listeria including Escherichia coli O157:H7 and Salmonella enteritidis. The detection limits of the ICA kit using the combination of gold-labeled MAb 7A3 and MAb 2B1 showed $1{\times}10^5$ and $1{\times}10^6\;CFU/0.1\;mL$ at 22 and $30^{\circ}C$, respectively. The other format of the ICA kit using the combination of gold-labeled rabbit polyclonal antibodies and MAb 2B1 showed $1{\times}10^6\;CFU/0.1\;mL$ at $22^{\circ}C$ but weak signal at 30 culture. The format utilizing MAb was more sensitive than the one using polyclonal antibodies for capture antibody. Samples contaminated with L. monocytogenes 4b culture (9-10, 5-6, and 1-2 CFU/mL) on pork and pasteurized milk were confirmed as positive results. Current data suggests that this ICA kit is a rapid, simple and effective tool to screen for Listeria spp. in food.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.5
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• pp.533-539
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• 2007

Cell culture infectivity assay using HCT-8 cell was combined with most-probable-number technique to evaluate the inactivation of Cryptosporidium parvum by various disinfectants, including chlorine, ozone, and UV light. The assay was demonstrated to be as sensitive as animal infectivity assay, which has been considered the "gold standard" for assessing Cryptosporidium oocyst infectivity, and a valuable tool to evaluate inactivation of C. parvum by disinfectants. Bench-scale inactivation study showed that at the condition of $5^{\circ}C$ and pH 7.0, CT value of $1,250mg{\cdot}min/L$ by chlorine and $16mg{\cdot}min/L$ by ozone were required to achieve approximately 1.0 log inactivation of C. parvum, suggesting that even ozone could not be sufficient to inactivate C, parvum at low. temperature. Unlike chlorine and ozone, UV light is very effective to inactivate C. parvum, regardless of temperature. A UV light dose of 2 $mJ/cm^2$ provided at least 3 log inactivation of C. parvum.

• Journal of Biosystems Engineering
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• v.35 no.2
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• pp.116-123
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• 2010

Rapid detection of foodborne pathogens has been a major challenge for the food industry. Salmonella contamination is well known in all foods including pasteurised milk. The possibility of specific detection of Salmonella Enteritidis by surface plasmon resonance (SPR) biosensor was explored using a commercially available portable SPR sensor. Self assembly technique was adopted to immobilize anti-Salmonella antibodies on the gold sensing surface of the SPR sensor. The concentration of polyclonal antibody for use in the SPR biosensor was chosen to 1.0 mg/mL. Experiments were conducted at near real-time with results obtained for one SPR biosensor assay within 1 hour. The limit of detection for Salmonella Enteritidis was determined to be $10^6$ CFU/mL in both PBS buffer and milk samples. The assay sensitivity was not significantly affected by milk matrix. Our results showed that it would be possible for employing the SPR biosensor to detect Salmonella Enteritidis in near real-time.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.27 no.3
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• pp.238-244
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• 2017

Objectives: The major objective of this study was to investigate the prevalence of and risk factors for latent tuberculosis infection (LTBI) among employees at a workers' compensation hospital. Methods: Among the 394 employees at Incheon Hospital, 362 were enrolled in the study. An interferon-gamma release assay(IGRA) for diagnosis of LTBI was performed using QuantiFERON$^{(R)}$ TB Gold In-Tube(QFT-IT). Risk factors for LTBI were analyzed using logistic regression analysis. Results: The overall prevalence of LTBI was 32.0%(116/362). The non-medical departments have a significantly high prevalence compared to medical departments(39.7% vs 23.2%). In multivariate logistic regression analysis, experience working in the pneumoconiosis hospital(OR, 3.6; 95% CI, 1.3-10.3) was associated with development of LTBI. Conclusions: Korean guidelines for the management of tuberculosis recommend annual regular health examinations for TB and LTBI for health care workers(HCWs). Considering the high prevalence of and risk factors for LTBI among non-HCWs, it suggests a need for annual regular health examinations for TB and LTBI for all employees at workers' compensation hospitals, including pneumoconiosis hospitals.

• Parasites, Hosts and Diseases
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• v.54 no.3
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• pp.329-334
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• 2016

Trichomoniasis caused by Trichomonas vaginalis is a common sexually transmitted disease. Its association with several health problems, including preterm birth, pelvic inflammatory disease, cervical cancer, and transmission of human immunodeficiency virus, emphasizes the importance of improved access to early and accurate detection of T. vaginalis. In this study, a rapid and efficient loop-mediated isothermal amplification-based method for the detection of T. vaginalis was developed and validated, using vaginal swab specimens from subjects suspected to have trichomoniasis. The LAMP assay targeting the actin gene was highly sensitive with detection limits of 1 trichomonad and 1 pg of T. vaginalis DNA per reaction, and specifically amplified the target gene only from T. vaginalis. Validation of this assay showed that it had the highest sensitivity and better agreement with PCR (used as the gold standard) compared to microscopy and multiplex PCR. This study showed that the LAMP assay, targeting the actin gene, could be used to diagnose early infections of T. vaginalis. Thus, we have provided an alternative molecular diagnostic tool and a point-of-care test that may help to prevent trichomoniasis transmission and associated complications.

• Tuberculosis and Respiratory Diseases
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• v.68 no.3
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• pp.155-161
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• 2010

Background: The tuberculin skin test (TST) has limitations in diagnosing a latent tuberculosis infection (LTBI). The interferon-gamma release assay (IGRA) was introduced to middle- and high-school students since 2009 by the Korea Centers for Disease Control and Prevention. The aim was to evaluate the utility of IGRA in diagnosing LTBI in middle- and high-school students. Methods: From August 2007 to July 2009, among suspected LTBI students showing TST induration with a 10 mm diameter and over with a normal chest x-ray in school students of Jeju city, 341 students underwent a Quanti FERON-TB Gold In-Tube (QFT-IT) test to confirm LTBI. Results: From 348 students showing a positive TST, a QFT-IT test was carried out on 341 students. The positive QFT-IT rate was 52.8% (=180/341). The positive QFT-IT rate was higher in high-school boys with a 15~19 mm diameter of induration in TST. Conclusion: With the introduction of IGRA for diagnosing LTBI in middle- and high-school students, approximately 47% of students who show a TST induration with a 10 mm diameter and over can avoid taking unnecessary preventive chemotherapy. These results suggest that IGRA is useful for diagnosing and controlling LTBI in Korean students.

• Korean Journal of Veterinary Service
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• v.30 no.4
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• pp.489-496
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• 2007

An oligonucleotide microarray system was developed for the simultaneous detection of porcine epidemic diarrhea virus, transmissible gastroenteritis virus, porcine enteric calicivirus, porcine group A and C rotavirus. RNAs of the reference viruses and porcine diarrhea samples were extracted and amplified using one-step multiplex RT-PCR in the presence of cyanine 5-dCTP and hybridized on the microarray chip that spotted the virus-specific oligonucleotides. This system were approximately 10-to 100-fold higher in sensitivity than conventional RT-PCR, and the assay time was less than 3 hours. The relative sensitivity and specificity were 92% and 72.2%, respectively, based on 102 porcine diarrhea samples using RT-PCR as gold standard. These results suggested that the oligonucleotide microarray system in this study be probably more reliable and reproducible means for detecting porcine enteric viruses and that it could be of substantial use in routine diagnostic laboratories.

• Korean Journal of Veterinary Service
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• v.22 no.1
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• pp.25-35
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• 1999

The prevalence of canine heartworm(Dirofilaria immitis) infection in 150 mixed-breed dogs(male : 54, female : 96) from February to December 1997 was investigated by using antigen test kit(ICT $GOLD^{TM}$ HW, Synbiotics, USA) based on immunochromatographic assay in Inchon city. Also, gross and histopathological findings of an antigen positive dog were carried out. The results were summarized as follows ; 1. Four dogs were positive from 150 tested dogs(2.7%). They were all more than 2 years old and infection rates in male and outdoor dogs was higher than those in female and indoor, respectively. Species of infected dogs were Pug(2) , German Sheperd(1) and Great-dane (1). 2. Regional infection rates were closely related with housing system in the city. 3. Pathological findings of antigen-positive dog was excessive enlargement, congestion and hemorrhage of lung and D immitis in heart and histologically hemosiderin, hypertrophy of pulmonary alveoli wall and irregular hypertrophy of pulmonary artery inner wall. Microfilaria was observed in pulmonary artery and arteriole, ventricle and splenic artery.

• Proceedings of the KIEE Conference
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• 1998.07g
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• pp.2556-2558
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• 1998

2-D microwell arrays for micro ELISA (Enzyme-Linked Immuno Solvent Assay) system were fabricated using micromachining technology. The materials for the bottom plate, top plate and sidewall of the microwell were used a #7740 glass, gold and silicon respectively considering bio-compatibility and easy fabrication. Cylindrical or groove shape microwells, which have about $100{\mu}m$ depth and $50{\sim}500{\mu}m$ diameter or width, were arrayed. The fabricated microwell array can be applied to the essential part of a biochip when surface modification is made to immobilize cells or biomolecules on the microwell bottom.

• Microbiology and Biotechnology Letters
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• v.33 no.2
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• pp.148-153
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• 2005

Malaria is a re-emerging infectious disease that is spreading to areas where it had been eradicated, such as Eastern Europe and Central Asia. To avoid the mortality from malaria, early detection of the parasite is a very important issue. The peripheral blood smear has been the gold standard method for the diagnosis of malaria infection. Recently, several other methods have been introduced for quantitative detection of malaria parasites. Real time PCR that employs fluorescent labels to enable the continuous monitoring of PCR product formation throughout the reaction has recently been used to detect several human malaria parasites. 18S rRNA sequences from malaria parasites have been amplified using Taqman real time PCR assay. Here, a SYBR Green-based real time quantitative PCR assay for the detection of malaria parasite-especially, Plasmodium vivax - was applied for the evaluation of 26 blood samples from Korean malaria patients. Even though SYBR Green-based real time PCR is easier and cheaper than Taqman-based assay, SYBR Green-based assay cannot be used because 18S rRNA cannot be specifically amplified using 1 primer set. Therefore, we used DBP gene sequences from Plasmodium vivax, which is specific for the SYBR Green based assays. We amplified the DBP gene from the 26 blood samples of malaria patients using SYBR Green based assay and obtained the copy numbers of DBP genes for each sample. Also, we selected optimal reference gene between ACTB and B2M using real time assay to get the stable genes regardless of Malaria titer. Using selected ACTB reference genes, we successfully converted the copy numbers from samples into titer, ${\sharp}$ of parasites per microliter. Using the resultant titer from DBP based SYBER Green assay with ACTB reference gene, we compared the results from our study with the titer from Taqman-based assay. We found that our results showed identical tendency with the results of 18S rRNA Taqman assay, especially in lower titer range. Thus, our DBP gene-utilized real time assay can detect Plasmodium vivax in Korean patient group semi-quantitatively and easily.