Background: Insulin is a hormone produced by the beta \r\n', u'cells of the pancreas that permits glucose to enter cells and \r\n', u'helps the body use glucose for energy. Insulin controls the \r\n', u'amount of glucose in the blood. Insulin is produced by recombinant protein technology. Expression of human proinsulin is the first step to express insulin. Objectives:To express successfully human proinsulin gene in pET 28a vector and E.coli BL21 (DE3). Subjects and method: Human proinsulin gene was applied from human pencreas cDNA by PCR using specific PINS primer pairs which contained sites for BamH I, Xho I. Proinsulin gene was cloned into pET 28a (+) vector to form recombinant vector pET 28a-PINS then transformed into E.coli BL21 (DE3) host strain to make pET 28a-PINS/ BL21 (DE3) clone. The clone was cultured and induced by IPTG (1mM). Recombine protein was analysed by SDS-PAGE. Results: Expression vector pET 28a-PINS was constructed successfully. Proinsulin protein expressed in E.coli BL21 (DE3) was purified by ProPond-Resin (Amersham). Conclusion: Human proinsulin was produced successfully using pET 28a-PINS/ BL21 (DE3) system.\r\n', u'
Proinsulin/ pharmacology ; pharmacokinetics ; Escherichia coli

Chikungunya virus (CHIKV), a tropical pathogen, has re-emerged and has massive outbreaks abruptly all over the world. Containing many dominant epitopes, the envelope E2 protein of CHIKV has been explored for the vaccination or diagnosis. In the present study, the antigenicity of a recombinant expressed intrinsically disorder domain (IUD) of E2 was tested for the detection of the antibody against CHIKV through western blot method. The gene of the IUD of E2 was inserted into 2 different vectors and expressed as recombinant GST-E2 and recombinant MBP-E2 fusion protein, respectively. Two kinds of fusion proteins were tested with 30 CHIKV patient sera and 30 normal sera, respectively. Both proteins were detected by 25 patients sera (83.3%) and 1 normal serum (3.3%). This test showed a relatively high sensitivity and very high specificity of the recombinant E2 proteins to be used as diagnostic antigens against CHIKV infection.
Blotting, Western* ; Chikungunya virus ; Diagnosis ; Disease Outbreaks ; Epitopes ; Humans* ; Sensitivity and Specificity ; Vaccination

ELISA has been used for the diagnosis of toxoplasmosis, but it is being gradually replaced by a rapid diagnostic test (RDT). We compared and analyzed ELISA and RDT results using the sera collected during 4 consecutive years from residents of Gyodong-do (Island), Incheon-city, Korea. Sera from 921, 993, 940, and 838 adult residents were collected on a yearly basis (2010–2013). ELISA was performed by using a crude extract of T. gondii RH strain antigen and IgG/IgM RDT mounted with recombinant fragment of major surface antigen (SAG1), GST-linker-SAG1A, were applied to the sera. Comparison between groups was analyzed by the Student’s t-test. The positive seroprevalence surged from 14.7% (135/921, 2010), 23.1% (231/993, 2011), 23.6% (222/940, 2012), and 32.1% (269/838, 2013) by ELISA. In contrast, RDT showed a more moderate increasing trend from 21.7% (200/921, 2010), 25.5% (253/993, 2011), 28.9% (272/940, 2012) and 33.1% (277/838, 2013). Discrepancies between ELISA and RDT were noted near the cut-off value. At the OD 0.15–0.24 range, RDT could detect 16.1% (169/1051) more positives, which suggests an early or acute toxoplasmosis, but at the OD 0.25–0.34 range, ELISA could detect 35.9% (92/256) more positives of possible chronic infections. Over the OD > 0.35 ELISA and RDT agreed in the majority of the cases. This surge in seroprevalence may be caused by the organic agriculture in addition to eating behavior or increase in pets among Koreans. These facts may be applied on a full-scale national survey using RDT to supplement ELISA to define the characteristics of the infection.
Adult ; Antigens, Surface ; Diagnosis ; Diagnostic Tests, Routine* ; Enzyme-Linked Immunosorbent Assay* ; Feeding Behavior ; Follow-Up Studies* ; Humans ; Incheon* ; Korea* ; Organic Agriculture ; Seroepidemiologic Studies* ; Toxoplasma ; Toxoplasmosis*

To evaluate the seroprevalence against circumsporozoite protein (CSP) of Plasmodium vivax in sera of Korean patients, the central repeating domain (CRD) of CSP was cloned and analyzed. From the genomic DNA of patient's blood, 2 kinds of CSPs were identified to belong to a VK210 type, which is the dominant repeating of GDRA(D/A)GQPA, and named as PvCSPA and PvCSPB. Recombinantly expressed his-tagged PvCSPA or PvCSPB in Escherichia coli reacted well against sera of patients in western blot, with the detecting rate of 47.9% (58/121), which included 15 cases positive for PvCSPA, 6 cases positive for PvCSPB, and 37 cases for both. The mixture of PvCSPA and PvCSPB was loaded to a rapid diagnostic test kit (RDT) and applied with the same set of patient sera, which resulted in detection rates of 57.0% (69/121). When the protein sequences of PvCSPA were compared with those of P. vivax in endemic regions of India and Uganda, they were compatibly homologous to PvCSPA with minor mutations. These results suggested that the recombinant PvCSPA and PvCSPB loaded RDT may be a milestone in latent diagnosis which has been a hot issue of domestic malaria and important for radical therapy in overlapped infections with P. falciparum in tropical and subtropical areas. During the biological process of malarial infection, exposure of CSP to antigen-antibody reaction up to 57.0% is the first report in Korea.
Amino Acid Sequence ; Antibodies, Protozoan/*blood/immunology ; Antibody Formation ; Antigens, Protozoan/immunology ; Base Sequence ; Humans ; India ; Malaria, Vivax/*diagnosis/*epidemiology/immunology ; Merozoite Surface Protein 1/genetics/*immunology ; Plasmodium vivax/genetics/immunology ; Protozoan Proteins/genetics/*immunology ; Reagent Kits, Diagnostic ; Recombinant Proteins/diagnostic use/immunology ; Republic of Korea/epidemiology ; Sequence Analysis, DNA ; Seroepidemiologic Studies ; Uganda

Toxoplasma gondii is an apicomplexan parasite with a broad host range of most warm-blooded mammals including humans, of which one-thirds of the human population has been infected worldwide which can cause congenital defects, abortion, and neonatal complications. Here, we developed a rapid diagnostic test (RDT) for T. gondii infection. Antigenic N-terminal half of the major surface antigen (SAG1) was linked with intrinsically unstructured domain (IUD) of dense granule protein 2 (GRA2). The recombinant GST-GRA2-SAG1A protein was successfully expressed and purified as 51 kDa of molecular weight. Furthermore, antigenicity and solubility of the rGST-GRA2-SAG1A protein were significantly increased. The overall specificity and sensitivity of GST-GRA2-SAG1A loaded RDT (TgRDT) were estimated as 100% and 97.1% by comparing with ELISA result which uses T. gondii whole cell lysates as the antigen. The TgRDT tested with Uganda people sera for field trial and showed 31.9% of seroprevalence against T. gondii antibody. The TgRDT is proved to be a kit for rapid and easy to use with high accuracy, which would be a suitable serodiagnostic tool for toxoplasmosis.
Adolescent ; Adult ; Amino Acid Sequence ; Antibodies, Protozoan/*blood ; Antigens, Protozoan/genetics/*immunology ; Child ; Child, Preschool ; Female ; Humans ; Infant ; Male ; Molecular Sequence Data ; Protozoan Proteins/genetics/*immunology ; Recombinant Fusion Proteins ; Reproducibility of Results ; Republic of Korea/epidemiology ; Sensitivity and Specificity ; Serologic Tests ; Time Factors ; Toxoplasma/genetics/*immunology/isolation & purification ; Toxoplasmosis/*diagnosis/epidemiology/parasitology ; Uganda/epidemiology ; Young Adult

Seroprevalence of Toxoplasma gondii infection among the residents of Seokmo-do (Island) in Ganghwa-gun, Incheon, Korea was surveyed for 4 years by a rapid diagnostic test (RDT) using recombinant fragment of major surface antigen (SAG1), GST-linker-SAG1A. Sera from 312, 343, 390, and 362 adult residents were collected on a yearly basis from 2010 to 2013, respectively. Total positive seroprevalence regardless of gender was 29.2, 35.3, 38.7, and 45.3% from 2010 to 2013, respectively. Positive seroprevalence in male adults was 43.9, 48.2, 45.4, and 55.3%, which was far higher than that of the corresponding female adults which was 20.7, 29.2, 33.9, and 38.9%, from 2010 to 2013, respectively. This high seroprevalence of toxoplasmosis in Seokmo-do may have been caused in part by peculiar changes in the toxoplasmic environment of the island as it is a relatively isolated area preserving its natural habitat while also being connected by a bridge to the mainland. Further study is necessary to find out symptomatic patients and to confirm the risk factors.
Adult ; Antigens, Surface ; Diagnostic Tests, Routine ; Ecosystem ; Female ; Humans ; Incheon* ; Korea* ; Male ; Risk Factors ; Seroepidemiologic Studies* ; Toxoplasmosis*

Feline leukemia virus (FeLV) causes a range of neoplastic and degenerative diseases in cats. To obtain a more sensitive and convenient diagnosis of the disease, we prepared monoclonal antibodies specific for the FeLV p27 to develop a rapid diagnostic test with enhanced sensitivity and specificity. Among these antibodies, we identified two clones (hybridomas 8F8B5 and 8G7D1) that specifically bound to FeLV and were very suitable for a diagnostic kit. The affinity constants for 8F8B5 and 8G7D1 were 0.35 x 10(9) and 0.86 x 10(9), respectively. To investigate the diagnostic abilities of the rapid kit using these antibodies, we performed several clinical studies. Assessment of analytical sensitivity revealed that the detection threshold of the rapid diagnostic test was 2 ng/mL for recombinant p27 and 12.5 x 10(4) IU/mL for FeLV. When evaluating 252 cat sera samples, the kit was found to have a kappa value of 0.88 compared to polymerase chain reaction (PCR), indicating a significant correlation between data from the rapid diagnostic test and PCR. Sensitivity and specificity of the kit were 95.2% (20/21) and 98.5% (257/261), respectively. Our results demonstrated that the rapid diagnostic test would be a suitable diagnostic tool for the rapid detection of FeLV infection in cats.
Animals ; Antibodies, Monoclonal/blood ; Cats ; Diagnostic Tests, Routine/*veterinary ; Female ; Gene Products, gag/*blood ; Leukemia Virus, Feline/immunology/*isolation & purification ; Leukemia, Feline/*diagnosis ; Mice, Inbred BALB C ; Sensitivity and Specificity

Seroprevalence of Toxoplasma gondii infection among the residents of Cheorwon-gun, Gangwon-do, Korea, which partly includes the demilitarized zone (DMZ), were surveyed for 4 years and evaluated by RDT using recombinant fragment of major surface antigen (SAG1A). Sera from 1336, 583, 526, and 583 adult residents were collected on a yearly basis from 2010 to 2013, respectively. The total positive seroprevalence was 19.3, 21.9, 23.4, and 26.8% from 2010 to 2013, respectively. The positive seroprevalence in men (23.6, 27.5, 29.5, 34.6%) was far higher than women (14.1, 18.3, 19.4, 21.4%), from 2010 to 2013, respectively. This high seroprevalence of toxoplasmosis in Cheorwon-gun may have been influenced in part by its geographical locality of the area as it includes the DMZ, where civilian access is strictly limited, thus creating a relatively isolated area that is a well-preserved habitat. Further research is necessary to study the epidemiology of toxoplasmosis in this area.
Adult ; Antigens, Surface ; Ecosystem ; Epidemiology ; Female ; Gangwon-do* ; Humans ; Korea* ; Male ; Seroepidemiologic Studies* ; Toxoplasma ; Toxoplasmosis*

Chagas disease is caused by the protozoan parasite Trypanosoma cruzi, and is endemic in many Latin American countries. Diagnosis is based on serologic testing and the WHO recommends two or more serological tests for confirmation. Acidic ribosomal P protein of T. cruzi showed strong reactivity against positive sera of patients, and we cloned the protein after fragmenting it to enhance its antigenicity and solubility. Twelve positive sera of Chagas disease patients were reacted with the fragmented ribosomal P protein using western blot. Detection rate and density for each fragment were determined. Fragments F1R1, F1R2, and F2R1 showed 100% rate of detection, and average density scoring of 2.00, 1.67, and 2.42 from a maximum of 3.0, respectively. Therefore, the F2R1 fragment of the ribosomal P protein of T. cruzi could be a promising antigen to use in the diagnosis of Chagas disease in endemic regions with high specificity and sensitivity.
Blotting, Western ; Chagas Disease ; Clone Cells ; Diagnosis ; Humans ; Parasites ; Sensitivity and Specificity ; Serologic Tests ; Solubility ; Trypanosoma cruzi

In recent years, rapid diagnostic tests (RDTs) have been widely used for malaria detection, primarily because of their simple operation, fast results, and straightforward interpretation. The Asan EasyTest(TM) Malaria Pf/Pan Ag is one of the most commonly used malaria RDTs in several countries, including Korea and India. In this study, we tested the diagnostic performance of this RDT in Uganda to evaluate its usefulness for field diagnosis of malaria in this country. Microscopic and PCR analyses, and the Asan EasyTest(TM) Malaria Pf/Pan Ag rapid diagnostic test, were performed on blood samples from 185 individuals with suspected malaria in several villages in Uganda. Compared to the microscopic analysis, the sensitivity of the RDT to detect malaria infection was 95.8% and 83.3% for Plasmodium falciparum and non-P. falciparum, respectively. Although the diagnostic sensitivity of the RDT decreased when parasitemia was < or =500 parasites/microl, it showed 96.8% sensitivity (98.4% for P. falciparum and 93.8% for non-P. falciparum) in blood samples with parasitemia > or =100 parasites/microl. The specificity of the RDT was 97.3% for P. falciparum and 97.3% for non-P. falciparum. These results collectively suggest that the accuracy of the Asan EasyTest(TM) Malaria Pf/Pan Ag makes it an effective point-of-care diagnostic tool for malaria in Uganda.
Adolescent ; Adult ; Antigens, Protozoan/blood/*isolation & purification ; Child ; Child, Preschool ; Humans ; Malaria, Falciparum/*diagnosis/epidemiology ; Parasitemia ; Point-of-Care Systems ; Predictive Value of Tests ; Reagent Kits, Diagnostic ; Sensitivity and Specificity ; Uganda/epidemiology ; Young Adult