• Parasites, Hosts and Diseases
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• v.29 no.4
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• pp.355-362
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• 1991

A total of 2,580 sera of the patients who were consulted to the serology laboratory of the Seoul National University Hospital were collected in 1990. The sera were screened by micro-ELISA to detect IgG antibody reacting with Pneumocystis carinii antigen. The absorbances were 0.00 to 1.41 and mean 0.27±0.253. As the positive criterion was set absorbance 0.2 or more with 70% sensitivity, total positive rate was 44.4oA. Mean absorbances and positive rates were higher in children than in adults; 0.40 and 62.9% in 0 year group, 0.50 and 81.2% in 1 year group, 0.41 and 66.0% in 2-3 year group, 0.33 and 61.4% in 4-5 year group, 0.25 and 42.3% in 6-10 year group respectively. In the age groups over 11 years, the absorbances were in range of 0.16 to 0.23 and the positive rates were 26.1% to 41.5%. The present level of absorbances and positive rates could be regarded similar with those in normal Korean population. The present findings suggest that most humans are exposed to Pneumocystis within 2 years after birth and meet much less new antigenic challenge after 11 years in Korea.

• Parasites, Hosts and Diseases
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• v.59 no.6
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• pp.565-572
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• 2021

Toxoplasma gondii ME49 infections are typically diagnosed by serological tests. However, serological diagnosis of RH strain-induced toxoplasmosis remains unknown. In order to develop seradiagnosis of above 2 kinds of infections, we generated recombinant virus-like particles (VLPs) displaying the T. gondii rhoptry protein 4 (ROP4) and evaluated their potential in T. gondii ME49 or RH strain infection diagnostics. Mice were orally infected with either the tachyzoites of T. gondii (RH) or cysts of T. gondii (ME49) at various dosages, and sera were collected at regular intervals. ELISA-based serological tests were performed to assess IgG, IgM, and IgA antibody responses against ROP4 VLP antigen and tissue lysate antigen (TLA). Compared to TLA, IgG, IgM, and IgA levels to ROP4 VLP antigen were significantly higher in the sera of T. gondii RH-infected mice 1 and 2 week post-infection (PI). T. gondii-specific IgG antibody was detected at 1, 2, 4, and 8 week PI in the T. gondii ME49-infected mice with infection dose-dependent manner. These results indicated that the ROP4 VLP antigen was highly sensitive antigens detecting T. gondii RH and ME49 antibodies at an early stage.

• Journal of fish pathology
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• v.36 no.2
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• pp.389-394
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• 2023

Infectious hematopoietic necrosis virus (IHNV) is s significant viral pathogen affecting cultured rainbow trout (Oncorhynchus mykiss) in Korea. In this study, five monoclonal antibodies (mAbs) (IHNV-1, 2, 3, 4, and 5) were produced using purified IHNV. Reactivities of these mAbs were analyzed by western blot (WB), enzyme-linked immunosorbent assay (ELISA), and indirect fluorescent antibody test (IFAT). These mAbs recognized glycoprotein (69 kDa, IHNV-1), nucleocapsid protein (39 kDa, IHNV-3, 4, and 5), or phosphoprotein (27 kDa, IHNV-2) of IHNV by WB analysis. ELISA results indicated that these five mAbs were specific to IHNV without showing any cross-reactivity against other fish viruses (hirame rhabdovirus, infectious pancreatic necrosis virus, and viral hemorrhagic septicemia virus). IFAT demonstrated specific fluorescence signals of IHNV-infected epithelioma papulosum cyprini (EPC) cells, whereas no reactivity of normal EPC cells was observed. These mAbs can be very useful for immuno-diagnosis of IHNV infection.

• Parasites, Hosts and Diseases
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• v.24 no.2
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• pp.159-170
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• 1986

A total of 69 patients of confirmed neurocysticercosis was followed serologically by ELISA up to 22 months after praziquantel treatment. The intervals and numbers of follow-up were variable by patient. Serially collected samples of serum and CSF were examined simultaneously for their specific IgG antibody levels by ELISA, using cystic fluid, saline extracts of bladder wall and scolex as antigen. Within 4 months after praziquantel treatment, the antibody levels were elevated temporarily in both serum and CSF in most patients. In some cases antibody levels exhibited steady declining tendency after the treatment. Concomitant administration of dexamethasone appeared to suppress the elevation of antibody levels. The rate of mean absorbance of antibody changed more in serum than in CSF. The rate of elevation was greater in antibodies to parenchymal antigens than that to cystic fluid, but absolute difference of antibody levels was greater in antibody to cystic fluid. Previously negative samples for IgG antibody may become positive after the praziquantel treatment, which could be used as a complementary tool (provocation test) in serodiagnosis. One month was considered to be sufficient interval for the follow-up test for that purpose. In the follow-up of up to 22 months, only few cases of chronic neurocysticercosis showed declining tendency of IgG antibody levels below negative range. During acute encephalitic attacks in chronic patients, IgG antibody to parenchymal antigen were elevated in CSF temporarily. These results indicated that serologic follow-up of every year was recommendable to differentiate the cured patients from chronic patients with slowly calcifying lesions.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.1
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• pp.295-301
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• 2017

Botulinum neurotoxin (BoNT/A) is a neurotoxin that selectively attacks the peripheral cholinergic nerve endings. It is produced by Gram -positive, endospore-forming strict anaerobic bacteria, Clostridium botulinum. Since BoNT/A could be a biothreat agent, as well as a contaminator of food and water supplies, the development of sensitive assays for toxin detection and potent antitoxin for the treatment of intoxication is necessary. In this study, for the purpose of producing monoclonal antibodies (mAbs) that are capable of neutralizing Botulinum neurotoxin type A (BoNT/A), scFv (single-chain variable domain fragment) libraries from the rabbit antisera against BoNT/A was fused to a human IgG. The resulting recombinant scFvIgG antibody protein was expressed in stable cell lines and was purified using a protein A affinity chromatography. The efficacy of scFvIgG mAb was confirmed by ELISA and was evaluated for the neutralization of BoNT/A in vivo. Such an in vivo toxin neutralization assay was performed using mice. Although scFvIgG antibody proteins (10 ug) failed to fully protect the mice challenged with BoNT/A (100,000 $LD_{50}$), it significantly prolonged the survival time. These results suggest that scFvIgG mAb may be capable of neutralizing BoNT/A single-chain variable domain fragment.

• Korean Journal of Food Science and Technology
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• v.42 no.3
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• pp.329-334
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• 2010

Escherichia coli O157:H7 causes hemolytic uremic syndrome and hemorrhagic colitis in humans. The objectives of this study were to produce monoclonal antibody(MAb) against E. coli O157:H7 and to develop an enzyme linked immunosorbent assay(ELISA) for the rapid detection of E. coli O157:H7 in agri-stockbreeding. The characterization of MAb produced from hybridoma cell (HKEC 4G8-5) was validated by ELISA and Western blot. The produced MAb was specific to E. coli O157:H7 and showed weak cross-reaction to Staphylococcus aureus. The detection limit of ELISA based on 4G8-5 MAb was $10^5\;cell/mL$. Although the ELISA could not detect E. coli O157:H7 in the meat and sprout samples inoculated with $1{\times}10^1\;cell$/10 g without enrichment, the same samples after enrichment for 6 hr were confirmed to be positive by ELISA. These results indicated that the ELISA combined with short enrichment (6 hr) is useful tool for rapid screening of E. coli O157:H7 in various samples.

• Journal of Food Hygiene and Safety
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• v.4 no.3
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• pp.171-176
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• 1989

A rapid, simple method of ELISA was applied for the determination of aflatoxin BI in cereals from Y oungnam districts. Antibodies obtained cross reacted with aflatoxin B2 and to a less extent with other aflatoxin BI analogs. Response range for a typical standard curve was between I and 100 ppb. Fewer interference by spiked methanol-PBSdimethylformamide extracts ofrice was evidenced. Contents of aflatoxin BI from rice (65) and barley (116) were determined by competitive direct enzyme- linked immunosorbent assay as follows. Three out of 65 rices samples were positive. Rice samples of R-IS, R-30, and R-59 represent the aflatoxin B1 levels of $7.5\;\mu\textrm{g}.kg,\;6.0\;\mu\textrm{g}/kg,\;3.5\;\mu\textrm{g}/kg,\;3.3\;\mu\textrm{g}/kg$, respectively, and showed 4.6% aflatoxin BI contamination in rice samples. Meanwhile, four out of 116 barley samples were positive. VB-37 showed the highest aflatoxin Bllevels of $9.6\;\mu\textrm{g}/kg$ and VB-35, VB-15 and VB-54 represent $7.5\;\mu\textrm{g}.kg,\;6.0\;\mu\textrm{g}/kg\;and\;3.6\;\mu\textrm{g}/kg$, respectively, and showed 3.4% aflatoxin B1 contamination in barley samples.

• Korean Journal of Food Science and Technology
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• v.40 no.3
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• pp.343-348
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• 2008

The ovomucoid (OM) of egg whites is recognized as a major allergen. Here, the allergenicity of OM in egg whites (EW) treated by chemical, enzymatic, and physiological methods were investigated by competitive inhibitory ELISA using human IgE antibody acquired from egg-allergic patients. Enzymatic hydrolysis, irradiation, and succinic anhydride treatments did not reduce the allergenicity of the OM effectively. Allergenicity was reduced to only 1/20 by deglycosylation with trifluoromethanesulfonic acid (TFMS). Heat treatment of the OM at $121^{\circ}C$ for 10 min reduced allergenicity to 1/100. Furthermore, NaOH (over 3%) treatment reduced allergenicity to 1/10,000, and the combinatory treatment of NaOH (over 0.3%) and heat ($70^{\circ}C$, 15 min) reduced it to less than 1/10,000, which was the most effective method. In this study, which analyzed treated EW using ELISA and patient-derived IgE, the OM allergenicity was nearly the same as its antigenicity according to ELISA using rabbit IgG. However, in the case of the TFMS-treated EW, the antigenicity was much lower than the allergenicity. These results suggest that the allergenicity of OM is slightly different from its antigenicity.

• Parasites, Hosts and Diseases
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• v.25 no.2
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• pp.141-148
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• 1987

Circulating antigens in rats experimentally infected with Paragonimus westermani were examined by ELISA. From a total of 22 albino rats, each fed with 25 metacercariae, blood samples were collected until 12 weeks after infection. The specific antibodies against P. westermani in the serum of an infected cat were purified by ammonium sulfate precipitation, DEAE anion-exchange chromatography and affinity chromatography serially. So-called double antibody sandwich ELISA method was used for the detection of circulating antigens. The results were as follows: Mean value of O.D. in control sera was O. 04 (S.D.=0. 04). After infection, mean O.D.(S.D.) values were changed serially: 0.03(0.01) at 0.5 week(3 days), 0.55(0.50) at 1 week, 0.69(0.45) at 1.5 week, O.20 (0.19) at 2 weeks and O.13(0.10) at 2.5 weeks of infection. They returned, thereafter, to the level before infection. When O. 16 (mean+3 S.D.) were considered as cut-off value, those higher than O. 16 were observed only in the sera collected between 1 and 2.5 weeks after infection. Average 8. 4 immature worms (2.2 from the lungs and pleural cavities; 6.2 from muscles) were recovered in a rat at 12 weeks after infection. The fact that circulating antigens were not detected after 3 weeks of infection was considered to the caused by the formation of antigen-antibady complexs.

• Journal of Veterinary Science
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• v.23 no.4
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• pp.55.1-55.12
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• 2022

Background: ASF was first reported in Kenya in 1910 in 1921. In China, ASF spread to 31 provinces including Henan and Jiangsu within six months after it was first reported on August 3, 2018. The epidemic almost affected the whole China, causing direct economic losses of tens of billions of yuan. Cause great loss to our pig industry. As ELISA is cheap and easy to operate, OIE regards it as the preferred serological method for ASF detection. P54 protein has good antigenicity and is an ideal antigen for detection. Objective: To identify a conservative site in the African swine fever virus (ASFV) p54 protein and perform a Cloth-enzyme-linked immunosorbent assay (ELISA) for detecting the ASFV antibody in order to reduce risks posed by using the live virus in diagnostic assays. Method: We used bioinformatics methods to predict the antigen epitope of the ASFV p54 protein in combination with the antigenic index and artificially synthesized the predicted antigen epitope peptides. Using ASFV-positive serum and specific monoclonal antibodies (mAbs), we performed indirect ELISA and blocking ELISA to verify the immunological properties of the predicted epitope polypeptide. Results: The results of our prediction revealed that the possible antigen epitope regions were A23-29, A36-45, A72-94, A114-120, A124-130, and A137-150. The indirect ELISA showed that the peptides A23-29, A36-45, A72-94, A114-120, and A137-150 have good antigenicity. Moreover, the A36-45 polypeptide can react specifically with the mAb secreted by hybridoma cells, and its binding site contains a minimum number of essential amino acids in the sequence 37DIQFINPY44. Conclusions: Our study confirmed a conservative antigenic site in the ASFV p54 protein and its amino acid sequence. A competitive ELISA method for detecting ASFV antibodies was established based on recombinant p54 and matching mAb. Moreover, testing the protein sequence alignment verified that the method can theoretically detect antibodies produced by pigs affected by nearly all ASFVs worldwide.