Microplate Hybridization Research Articles

A Rapid and Accurate Detection Approach for Multidrug-Resistant Tuberculosis Based on PCR-ELISA Microplate Hybridization Assay.

Rapid and accurate diagnosis of multidrug-resistant tuberculosis (MDR-TB) is important for timely and appropriate therapy. In this study, a rapid and easy-to-perform molecular test that integrated polymerase chain reaction (PCR) amplification and a specific 96-well microplate hybridization assay, called PCR-ELISA (enzyme-linked immunosorbent assay), were developed for detection of mutations in rpoB, katG, and inhA genes responsible for rifampin (RIF) and isoniazid (INH) resistance and prediction of drug susceptibility in Mycobacterium tuberculosis clinical isolates. We evaluated the utility of this method by using 32 multidrug-resistent (MDR) isolates and 22 susceptible isolates; subsequently, we compared the results with data obtained by conventional drug susceptibility testing and DNA sequencing. The sensitivity and specificity of the PCR-ELISA test were 93.7% and 100% for detecting RIF resistance, and 87.5% and 100% for detecting INH resistance, respectively. These results were comparable to those yielded by commercially available molecular tests such as the GenoType MTBDRplus assay. Based on the aforementioned results, we conclude that the PCR-ELISA microplate hybridization assay is a rapid, inexpensive, convenient, and reliable test that will be useful for rapid diagnosis of MDR-TB, for improved clinical care.

Multivirus Detection from Japanese Landraces of Potato by Reverse Transcription–Polymerase Chain Reaction–Microplate Hybridization

In Japan, 12 viruses have been identified as causal agents of virus diseases of potato: Alfalfa mosaic virus, Cucumber mosaic virus, Potato aucuba mosaic virus, Potato leafroll virus (PLRV), Potato mop-top virus (PMTV), Potato virus A (PVA), Potato virus M (PVM), Potato virus S (PVS), Potato virus X (PVX), Potato virus Y (PVY), Tomato ringspot virus (ToRSV), and Tomato spotted wilt virus (TSWV). In a preliminary survey for viruses using ELISA, we found numerous virus species in landrace potatoes but only a few, e.g., PVY, in commercial ware potato crops. We have now modified a reverse transcription–polymerase chain reaction–microplate hybridization technique, developed for PVY, PLRV, and PMTV, to assay for the 12 viruses referred to above simultaneously. In leaf samples from 35 landraces, PVM, PVS, PVY, PLRV, PVA, and PVX were detected in 94%, 91%, 80%, 77%, 57%, and 43% of the landraces, respectively. These results indicate that potato landraces can act as a reservoir for these viruses with some landraces being asymptomatic. It is thus important to inspect and test for these viruses in seed potato production.

Implication of antigen-driven mechanisms in the pathogenesis of interstitial pneumonia associated with polymyositis

Event Abstract Back to Event Implication of antigen-driven mechanisms in the pathogenesis of interstitial pneumonia associated with polymyositis Akira Takeda1, 2*, Yasutsugu Fukushima3, Takaji Matsutani4, Yoichiro Haji2, Ryo Rokutanda2, Yasuhiro Suyama2, Mitsumasa Kishimoto2, Kenichi Yamaguchi2 and Masato Okada2 1 International University of Health and Welfare Hospital, Division of Clinical Immunology & Rheumatology, Japan 2 St. Luke's International Hospital, Division of Allergy & Rheumatology, Japan 3 Dokkyo University School of Medicine, Department of Pulmonary Medicine and Clinical Immunology, Japan 4 Wakayama Medical University, Laboratory of Immune Regulation, Japan Objective: Connective tissue diseases (CTDs) frequently involve the lung. Polymyositis (PM) is a major CTD characterized by chronic inflammatory lesions of muscle and other organs, including critical pulmonary involvement. Interstitial lung diseases, mainly interstitial pneumonia (IP), have been recognized in 30% - 70% of PM patients and have a poor prognosis. While the presence of myositis-specific autoantibodies suggests an autoimmune etiology of PM, the pathogenesis of PM-associated IP remains unclear. The aim of this study was to elucidate the role of T cells in this pulmonary complication. Methods: We took advantage of a rare opportunity to carefully study the cases of earliest-stage IP associated with PM by utilizing lung biopsy tissue. We characterized the phenotype of lung-infiltrating lymphocytes from lung biopsy specimens obatained by video-assisted thoracoscopy, and analyzed T-cell receptor a-chain (TCR Va) and TCR b-chain (TCR Vb) variable region repertoires of T-cells infiltrating the lung tissues using a validated adaptor ligation polymerase chain reaction (PCR)-based microplate hybridization assay, comparing these to peripheral blood lymphocytes (PBL). As expected, no TCR signals were detected from non-IP lung tissue controls. Results: The cases demonstrated substantial CD3+ T cell lung infiltrates. The usage of repertoires of TCR Va/Vb in the lung differed from those in PBL, with certain TCR V gene families detected more frequently in lung tissue, suggesting a pivotal role for T cells in the pathogenesis of IP associated with PM. This is the first robust demonstration of selective TCR repertoire usage and its differential expression in lung tissue versus PBL. Conclusion: These findings strongly suggest a pathogenic contribution of organ-specific oligoclonal T cell accumulation through antigen-driven immune mechanisms, implying potential development of immunospecific treatments such as molecular-targeted therapies. Acknowledgements The authors thank G. Deshpande, MD, for help with editing. This study was supported by the Ministry of Education, Science and Technology in Japan. Keywords: Interstitial Lung Disease, Interstitial pneumonia, Polymyositis, Dermatomyositis, Lung biopsy, Cell infiltrates, phenotypes, T cell, T cell receptor (TCR), T cell receptor repertoir, PCR, hybridization assay, Humans Conference: 15th International Congress of Immunology (ICI), Milan, Italy, 22 Aug - 27 Aug, 2013. Presentation Type: Abstract Topic: Immune-mediated disease pathogenesis Citation: Takeda A, Fukushima Y, Matsutani T, Haji Y, Rokutanda R, Suyama Y, Kishimoto M, Yamaguchi K and Okada M (2013). Implication of antigen-driven mechanisms in the pathogenesis of interstitial pneumonia associated with polymyositis. Front. Immunol. Conference Abstract: 15th International Congress of Immunology (ICI). doi: 10.3389/conf.fimmu.2013.02.00414 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 11 Apr 2013; Published Online: 22 Aug 2013. * Correspondence: Dr. Akira Takeda, International University of Health and Welfare Hospital, Division of Clinical Immunology & Rheumatology, Nasushiobara, Tochigi, 329-2763, Japan, atakeda123@gmail.com Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Akira Takeda Yasutsugu Fukushima Takaji Matsutani Yoichiro Haji Ryo Rokutanda Yasuhiro Suyama Mitsumasa Kishimoto Kenichi Yamaguchi Masato Okada Google Akira Takeda Yasutsugu Fukushima Takaji Matsutani Yoichiro Haji Ryo Rokutanda Yasuhiro Suyama Mitsumasa Kishimoto Kenichi Yamaguchi Masato Okada Google Scholar Akira Takeda Yasutsugu Fukushima Takaji Matsutani Yoichiro Haji Ryo Rokutanda Yasuhiro Suyama Mitsumasa Kishimoto Kenichi Yamaguchi Masato Okada PubMed Akira Takeda Yasutsugu Fukushima Takaji Matsutani Yoichiro Haji Ryo Rokutanda Yasuhiro Suyama Mitsumasa Kishimoto Kenichi Yamaguchi Masato Okada Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

A new method for quantitative analysis of the T cell receptor V region repertoires in healthy common marmosets by microplate hybridization assay

The common marmoset, Callithrix jacchus, is one of the smallest primates and is increasingly used for an experimental nonhuman primate model in many research fields. Analysis of T cell receptor (TCR) repertoires is a powerful tool to investigate T cell immunity in terms of antigen specificity and variability of TCR expression. However, monoclonal antibodies specific for many TCR Vα or Vβ chains have not been created. We have recently identified a large number of TCRα chain variable (TRAV) and TCRβ chain variable (TRBV) sequences from a cDNA library of common marmosets. The purpose of this study is to develop a new method for analysis of TCR repertoires in the common marmoset using this sequence information. This method is based on a microplate hybridization technique using 32 TRAV-specific and 32 TRBV-specific oligoprobes following an adaptor-ligation PCR. This enables the easy quantitation of the respective TRAV and TRBV expression levels. No cross-hybridization among specific-oligoprobes and very low variances in repeated measures of the same samples was found, demonstrating high specificity and reproducibility. Furthermore, this method was validated by an antihuman Vβ23 antibody which specifically bound to marmoset Vβ23. Using this method, we analyzed TCR repertoires from various tissue samples (PBMCs, spleen, lymph node and thymus) and isolated T cell subpopulations (CD4+CD8+, CD4+CD8− and CD4−CD8+) from the thymus of 10 common marmosets. Neither tissue-specific nor T cell subpopulation-specific differences was found in TRAV and TRBV repertoires. These results suggest that, unlike mice, TCR repertoires in the common marmoset are not affected by endogenous superantigens and are conserved among individuals, among tissues, and among T cell subpopulations. Thus, TCR repertoire analysis with high specificity and reproducibility is a very useful technique, with the potential to replace flow cytometric analysis using a panel of TRV-specific antibodies, many of which remain unavailable.

Evaluation of DNA-DNA hybridization method for identification of mycobacteria using a colorimetric microplate kit

DNA-DNA hybridization was applied for identification of mycobacteria and developed as a kit "microplate hybridization kit" (refers to MPHD) by Kobayashi Pharmaceutical Co. We received test samples of the microplates from the company and examined them for their and reliability using 180 mycobacterial strains of 21 species kept in our laboratory. The results of identification by MPHD were 100% identical to those of biochemical identification in the type or reference strains of mycobacteria, showing good reliability of MPHD method. Among clinical isolates, there were six M. tuberculosis strains which did not show typical characteristics for M. tuberculosis, i.e., niacin test negative or nitrate reduction weak positive, but all of these were identified as M. tuberculosis complex by MPHD method. Some strains from clinical isolates showed difference in identification between MPHD and biochemical methods: M. avium complex, identified biochemically were divided into M. avium and M. intracellulare by MPHD, M. fortuitum complex by biochemical identification were distinguished as M. fortuitum and M. chelonae by MPHD. Further, M. chelonae were separated into M. chelonae subsp. chelonae and M. chelonae subsp. abscessus by MPHD. M. peregrinum has been considered as a synonym of M. fortuitum, but we could distinguish M. peregrinum from M. fortuitum clearly by MPHD method. Thus, it is suggested that M. peregrinum and M. fortuitum are different species. Keys for getting reliable results using the MPHD kit are: (1) appropriate amount of bacteria for use, (2) purification of DNA, (3) enough deproteinization, and (4) appropriate timing to read colorimetry measurement of the plate.

Microplate electrochemical DNA detection for phosphinothricin acetyltransferase gene sequence with cadmium sulfide nanoparticles

An electrochemical DNA detection method for the phosphinothricin acetyltransferase (PAT) gene sequence from the transgenetic plants was established by using a microplate hybridization assay with cadmium sulfide (CdS) nanoparticles as oligonucleotides label. The experiment included the following procedures. Firstly target PAT ssDNA sequences were immobilized on the polystyrene microplate by physical adsorption. Then CdS nanoparticle labeled oligonucleotide probes were added into the microplate and the hybridization reaction with target ssDNA sequences took place in the microplate. After washing the microplate for three times, certain amounts of HNO 3 were added into the microplate to dissolve the CdS nanoparticles anchored on the hybrids and a solution containing Cd 2+ ion was obtained. At last differential pulse anodic stripping voltammetry (DPASV) was used for the sensitive detection of released Cd 2+ ion. Based on this principle a sensitive electrochemical method for the PAT gene sequences detection was established. The voltammetric currents of Cd 2+ were in linear range with the target ssDNA concentration from 5.0 × 10 − 13 to 1.0 × 10 − 10 mol/L and the detection limit was estimated to be 8.9 × 10 − 14 mol/L (3 σ). The proposed method showed a good promise for the sensitive detection of specific gene sequences with good selectivity for the discrimination of the mismatched sequences.

Microplate hybridization assay for detection of isoniazid resistance in Mycobacterium tuberculosis

Early and accurate detection of drug resistant Mycobacterium tuberculosis can improve both the treatment outcome and public health control of tuberculosis. A number of molecular-based techniques have been developed including ones using probe molecules that target drug resistance-related mutations. Although these techniques are highly specific and sensitive, mixed signals can be obtained when the drug resistant isolates are mixed with drug susceptible isolates. In order to overcome this problem, we developed a new drug susceptibility test (DST) for one of the most effective anti-tuberculosis drug, isoniazid. This technique employed a microplate hybridization assay that quantified signals from each probe molecule, and was evaluated using clinical isolates. The evaluation analysis clearly showed that the microplate hybridization assay was an accurate and rapid method that overcame the limitations of DST based on conventional molecular techniques.

Electrochemical DNA hybridization assay for the FMV 35S gene sequence using PbS nanoparticles as a label

An electrochemical DNA detection method was developed for the 35S promoter from Figwort mosaic virus (FMV 35S) gene sequence by using a microplate hybridization assay with PbS nanoparticles as labels. There are four main steps in the procedure including target FMV 35S ssDNA immobilization on the microplate, the hybridization of ssDNA with a PbS NPs-labeled oligonucleotide probe, the dissolution of the PbS anchored on the hybrids by the addition of HNO3 and the detection of released Pb (II) by differential pulse anodic stripping voltammetry. Based on this principle, the voltammetric response of Pb (II) was linearly related to the logarithm of the target FMV 35S concentration in the range from 8.0 × 10−13 to 1.6 × 10−10 mol L−1. The detection limit is 2.5 × 10−13 mol L−1 (3σ).

Development of rapid coagulase serotyping method by PCR and microplate hybridization

We developed a novel PCR-based method for coagulase serotyping. Coagulase gene amplicons biotinylated by PCR were identified by microplate hybridization (MPH) using serotype-specific probes. The conventional serotyping method, which is strongly dependent on coagulase activity, may sometimes give a mistaken determination of the serotype, especially in cases where there is high coagulase activity. In contrast, the results of PCR-MPH are not affected by coagulase activity. Furthermore, once the isolated colonies are obtained, it only takes 3 h to perform PCR-MPH, and the interpretation of the results is entirely objective. We compared PCR-MPH with the conventional method for 90 strains of coagulase-producing Staphylococcus aureus. The same results were found for both the PCR-MPH and conventional methods, and thus, our results indicate that PCR-MPH is a rapid, objective, and reliable method for coagulase serotyping.

Prevalence of herpes B virus genome in the trigeminal ganglia of seropositive cynomolgus macaques

Herpes B virus infection is almost asymptomatic in macaques (Macaca spp.), which are the natural hosts of this pathogen, but is the cause of high mortality in humans. Reactivation of the latent virus in the trigeminal ganglia (TG) results in the shedding of infectious particles into the oral mucosal membrane. Saliva contaminated with the reactivated virus from the ganglia of the natural host is considered to be important for viral transmission to humans and other monkeys. In the present study, we investigated the prevalence of the herpes B virus genome in the left and right TG of seropositive asymptomatic cynomolgus macaques. The latent virus genome was detected using a polymerase chain reaction and microplate hybridization assay. We found that the virus DNA was present in one or both TG of 12 of the 30 macaques (40%) tested, with the virus being detected from both TG in five of the 12 macaques and from a single TG in the remaining seven.

Performance of RT-PCR-ELISA for the detection of peste des petits ruminants virus

A highly sensitive and specific reverse transcription polymerase chain reaction enzyme linked immunosorbent assay (RT-PCR-ELISA) was developed for the objective detection of nucleoprotein (N) gene of peste des petits ruminants (PPR) virus from field outbreaks or experimentally infected sheep. Two primers (IndF and Np4) and one probe (Sp3) available or designed for the amplification/probing of the ‘N’ gene of PPR virus, were chosen for labeling and use in RT-PCR-ELISA based on highest analytical sensitivity of detection of infective virus or N-gene containing recombinant plasmid, higher nucleotide homology at the primer binding sites of the ‘N’ gene sequences available and the ability to amplify PPR viral genome from different sources of samples. RT-PCR was performed with unlabeled IndF and Np4 digoxigenin labeled primers followed by a microplate hybridization probe reaction with biotin labeled Sp3 probe. RT-PCR-ELISA was found to be 10-fold more sensitive than the conventional RT-PCR followed by agarose gel based detection of PCR product. Based on the Mean (mean ± 3S.D.) optical density (OD) values of 47 RT-PCR negative samples, OD values above 0.306 were considered positive in RT-PCR-ELISA. A total of 82 oculo-nasal swabs and tissue samples from suspected PPR cases were analyzed by RT-PCR and RT-PCR-ELISA, which revealed 54.87 and 58.54% positivity, respectively. From an experimentally infected sheep, both RT-PCR and RT-PCR-ELISA could detect the virus from 6 days post-infection up to 9 days in oculo-nasal swabs. On post-mortem, PPR viral genome was detected in spleen, lymph node, lung, heart and liver. The correlation co-efficient between RT-PCR-ELISA OD values and either TCID 50 of virus or molecules of DNA was 0.622 and 0.657, respectively. The advantages of RT-PCR-ELISA over the conventional agarose gel based detection of RT-PCR products are discussed.

New Commercially Available PCR and Microplate Hybridization Assay for Detection and Differentiation of Human Polyomaviruses JC and BK in Cerebrospinal Fluid, Serum, and Urine Samples

JC and BK human polyomaviruses (family Polyomaviridae) may cause severe neurological or urinary tract pathologies in immunocompromised hosts. In the present study, we evaluated a new commercially available PCR and microplate colorimetric hybridization assay for the standardized differential detection of JC virus (JCV) and BK virus (BKV) genomes in clinical samples. This JC/BK Consensus test was first evaluated by testing serial dilutions of JCV or BKV plasmid DNA standards and was then compared with an in-house reference PCR assay for the detection of JC and BK virus genomes in 70 cerebrospinal fluid (CSF) samples of patients with neurological disorders and in 75 serum or plasma samples and 125 urine samples of renal graft recipients. This new test allowed a limit of detection of 10 copies and 1 copy of JC and BK virus genomes, respectively, and was able to differentiate various levels of JCV, BKV, and mixed JCV and BKV DNA genomes in a single reaction tube. Our results showed 100% specificity and sensitivity for the JC/BK Consensus test with CSF samples. With serum or plasma samples, this test had a sensitivity and a specificity of 100% for both JCV and mixed JCV and BKV DNA detection and a sensitivity and a specificity of 100 and 97.8% for BKV DNA detection, respectively. With urine samples, the sensitivity and specificity were 100 and 96.6%, respectively, for JCV DNA detection; 100 and 89.4%, respectively, for BKV DNA detection; and 44.4 and 100%, respectively, for mixed JCV and BKV DNA detection. In conclusion, our data indicate that this new test, the JC/BK Consensus test, is valuable for the sensitive and specific differential detection of single JCV and BKV infections in CSF, serum or plasma, and urine samples. The use of this reliable PCR assay would improve the routine virological diagnosis as well as the clinical care of immunocompromised patients with polyomavirus-related pathologies.

Development and Evaluation of Chlamylege, a New Commercial Test Allowing Simultaneous Detection and Identification of Legionella , Chlamydophila pneumoniae , and Mycoplasma pneumoniae in Clinical Respiratory Specimens by Multiplex PCR

This study describes the development and evaluation of a new commercial test, Chlamylege (Argene Inc.), which allows the simultaneous detection in respiratory samples of Chlamydophila pneumoniae, Mycoplasma pneumoniae, and most Legionella species, as well as PCR inhibitors, by using a multiplex PCR and microplate hybridization. The sensitivities of Chlamylege were 1 x 10(-3) IFU, 5 x 10(-2) color-changing units, and 1 CFU per reaction tube for C. pneumoniae, M. pneumoniae, and Legionella pneumophila, respectively. A cohort of 154 clinical samples from patients with documented respiratory infections was analyzed by the kit, including 2 samples from patients with C. pneumoniae infection, 9 samples from patients with M. pneumoniae infection, 19 samples from patients with Legionella species infection, and 114 samples that tested negative for the three pathogens. All the positive specimens were correctly detected and identified by the Chlamylege kit, and no false-positive result was observed with the negative samples. The kit was then evaluated in a pediatric prospective study that included 220 endotracheal aspirates, and the results were compared with those obtained by three single in-house PCR assays. Four specimens were found to be positive for C. pneumoniae and six were found to be positive for M. pneumoniae by using both strategies. The Chlamylege kit detected two additional samples positive for M. pneumoniae and one additional sample positive for a Legionella species other than L. pneumophila; these three samples were shown to be true positive by other techniques. These overall results demonstrate that the Chlamylege assay is sensitive, specific, and convenient for the rapid detection and identification of atypical pathogens in clinical samples from patients with respiratory infections.

A Case of Systemic Osteomyelitides Due to Mycobacterium avium

A case of multiple osteomyelitides due to Mycobacterium avium (M. avium) infection with osteosclerotic bone lesions is reported. A 67-year-old male had been suffering from persistent fever and back pain since October 1999, and 20.0-2.5 mg prednisolone per day was prescribed for continuous inflammatory symptoms in January 2000. Six months later, computed tomography revealed osteosclerotic lesions in the left femur and thoracic vertebrae, but no skin lesion associated with mastocytosis or internal malignancy was identified. In September of 2002, a dome-shaped, soft subcutaneous tumor developed on the upper sternum. Histopathological findings revealed subcutaneous adipose tissue with several foci of tiny abscesses. Two weeks later, creamy pus was discharged through a draining sinus at the center of the wound. M. avium was demonstrated in the pus by Zeel-Nielsen staining and microplate hybridization.

Specific detection and identification of herpes B virus by a PCR-microplate hybridization assay.

Herpes B virus DNA was specifically amplified by PCR, targeting the regions that did not cross-react with herpes simplex virus (HSV). The amplified products, which were shown to be highly genetic polymorphisms among herpes B virus isolates, were identified by microplate hybridization with probes generated by PCR. The products immobilized in microplate wells were hybridized with the biotin-labeled probes derived from the SMHV strain of herpes B virus. The amplified products derived from the SMHV and E2490 strains of herpes B virus were identified by microplate hybridization. PCR products amplified from the trigeminal ganglia of seropositive cynomolgus macaques were identified as herpes B virus DNA. The utility of the PCR-microplate hybridization assay for genetic detection and identification of the polymorphic region of herpes B virus was determined.

Detection of foot and mouth disease virus by RT-PCR and microplate hydridization assay using inactivated viral antigens.

A single step RT-PCR was tested for detection of foot and mouth disease virus (FMDV) and immunoenzymatic determination of amplified products in a microplate hybridization assay. Inactivated reference strains (ELISA antigen) of all seven serotypes were used to optimize the test. Oligonucleotide primers were selected from two different genomic regions coding for RNA polymerase and VP1 protein, respectively. The RT-PCR used to amplify the polymerase gene specific RNA detected FMDV strains A, C, O, Asial and SAT1, and the identity of the fragments obtained was confirmed with a specific internal biotin-labelled capture probe. For the amplification of the VP1 genome region, two sets of oligonucleotide primers were used. One primer pair was successfully applied for the detection of serotypes A, C, O and Asial and a second one for serotypes SAT1, SAT2, SAT3. The specific probe enabled the detection of all the amplified products in a PCR ELISA test. By comparison with antigen ELISA, the PCR ELISA method allowed the detection of smaller amounts of FMDV in the inactivated material examined. The application of molecular diagnostic methods to inactivated antigens offers a good alternative procedure for developing and optimizing a sensitive method for detection of FMDV in laboratories that are not allowed to work with viable FMDV.

Escherichia albertii sp. nov., a diarrhoeagenic species isolated from stool specimens of Bangladeshi children.

The taxonomic position of a group of five D-sorbitol- and lactose-negative enterobacterial isolates recovered from diarrhoeal stools of children at the International Centre for Diarrhoeal Disease Research, Bangladesh (ICDDR,B), was investigated by DNA-DNA hybridization, phenotypic characterization and 16S rDNA sequencing. These strains were originally identified as 'Hafnia alvei-like' with the API 20E system but, in fact, show more phenotypic and genotypic resemblance to members of the genus Escherichia. By 16S rDNA sequencing, one representative strain of the ICDDR,B group was shown to be closely affiliated to the genera Escherichia and Shigella. Using the fluorimetric microplate hybridization method, the diarrhoeagenic ICDDR,B isolates were found to constitute a homogeneous taxon (> or = 82% internal DNA relatedness), with the closest affiliation to the type strains of Escherichia coli (55-64%) and Shigella flexneri (54-60%). The DNA-DNA hybridization levels were much lower with members of other described Escherichia species (16-45%) and with the type strain of H. alvei (9-17%). The G + C content of the ICDDR,B strains ranged from 50.5 to 50.7 mol%. Together with the diagnostic characteristics reported previously, including the presence of the eaeA gene of enteropathogenic E. coli and of the E. coli and Shigella-specific phoE gene, it is concluded that the ICDDR,B strains represent a novel taxon in the genus Escherichia, for which the name Escherichia albertii sp. nov. is proposed. Its type strain is Albert 19982(T) (= LMG 20976(T) = CCUG 46494(T)).

Novel assay of competitively differentiated polymerase chain reaction for screening point mutation of hepatitis B virus.

Point mutation, one of the commonest gene mutations, is the most important molecular pathogenesis of cancer and chronic infection. The commonest methods for detection of point mutation are based on polymerase chain reaction (PCR). These techniques, however, cannot be used in large scale screening since they are neither accurate nor simple. For this reason, this study established a novel method of competitively differentiated PCR (CD-PCR) for screening point mutation in clinical practice. Two competitively differentiated primers for mutant-type and wild-type templates respectively with an identically complemented region in 3' end except for last 2 base pairs and a different non-complemented region in 5' end were designed. Thus, competitive amplification might be carried out at a lower annealing temperature at first, and then differentiated amplification at a higher annealing temperature when primers could not combine with initial templates. The amplification was performed in one-tube. The products of CD-PCR were detected using microplate hybridization assay. CD-PCR was evaluated by detecting G1896A variant of hepatitis B virus (HBV) in form of recombinant plasmids and in sera from patients with hepatitis B, and compared with allele-specific PCR (AS-PCR) and competitive AS-PCR. CD-PCR was successfully established. It could clearly distinguish wild-type and mutant-type plasmid DNA of G1896A variant when the amount of plasmid DNA was between 10(2)-10(8)copies/reaction, while for AS-PCR and competitive AS-PCR, the DNA amount was between 10(2)-10(4)copies/reaction. CD-PCR could detect one copy of G1896A variant among 10-100 copies of wild-type plasmid DNA. The specificity of CD-PCR was higher than those of AS-PCR and competitive AS-PCR in the detection of HBV G1896A variant in sera from patients with hepatitis B. CD-PCR was independent of the amount of HBV DNA in serum. HBV G1896A variant was more often found in HBeAg (-) patients with a lower level of detectable viremia than that with a higher level of detectable viremia (P=0.0192). CD-PCR is more specific since it is less influenced by the amount of initial templates and the cross amplification between mutant- and wild-type amplified products. It is also simple and time-saving. Thus, CD-PCR might be useful in routine gene typing and point mutation screening. HBV G1896A or other more important mutations have to be routinely detected in patients with a detectable level of viremia after HBeAg/antibody conversion in clinical practice.

Does Streptococcal Pyrogenic Exotoxin-C Trigger the Onset of Kawasaki Disease? -Association between Superantigens and Autoantibody against Vascular Smooth Muscle Cells-

I) T cell receptor (TCR) usage We investigated TCR usage and antibody responses to streptococcal pyrogenic exotoxin-C (SPE-C) in order to determine whether an association exists between SPE-C and the onset of Kawasaki disease (KD). Patients and Method Fifty-four patients with KD were studied. Analysis of TCR usage was performed by adaptor-ligation PCR and microplate hybridization assay. Serum levels of antibody against SPE-C were assessed by ELISA using purified recombinant protein. Results Forty (74.1%) of the patients with KD showed significant polyclonal activation of Vβ2- and/or Vβ-6.5-bearing T cells. In 22 of 35 paired patients with KD, serum levels of anti-SPE-C antibodies (IgM) in the convalescent phase were lower than those in the acute phase. II) Detection of autoantibodies against vascular smooth muscle cells To investigate the pathogenesis of vasculitis in KD, we tested for the presence of autoantibodies against vascular smooth muscle cells in the patients. Patients and Methods Sera from 48 patients with KD were examined for reactivity with both coronary arterial wall tissues and cultured smooth muscle cells (CSMC) derived from human coronary artery, using immunofluorescence and Western immunoblotting. Results Sera from 16 of 48 patients with KD gave positive immunoreactions with the smooth muscle cells of coronary artery with anti-human IgA antibodies. Western immunoblotting revealed positive reactions of sera from 15 of 34 and 10 of 31 patients with KD against a 70-kDa protein from CSMC with IgA and IgM antibodies, respectively. Positive immunoreactivity of sera from KD patients was detected more frequently in patients with coronary arterial lesions (CAL) than in those without CAL (p <0.05). Conclusions These results suggest that an association may exist between SPE-C and the onset of KD. In addition, autoantibody against vascular smooth muscle cells may cause systemic vasculitis in KD.

Secretion and dynamics of herpes simplex virus in tears and saliva of patients with Bell's palsy.

For clarification of the direct relationship between the reactivation of herpes simplex virus and the development of Bell's Palsy, a detection of the virus genome by deoxyribonucleic acid diagnostics and a quantitative analysis of its time-course change are both needed. The authors detected the HSV genome in specimens from patients with Bell's Palsy, quantified its number of copies, and examined time-course changes. The subjects were 16 patients with Bell's Palsy. The tear fluid and saliva from the submandibular gland and the parotid gland were separately collected from the affected and unaffected sides twice or more. A total of 244 specimens were subjected to extraction of deoxyribonucleic acid, polymerase chain reaction, and microplate hybridization. Herpes simplex virus-1 deoxyribonucleic acid was detected in 38 specimens (11.8%) from 5 patients (31%). The high detection (28.5%) was obtained within 2 weeks after onset. Detection at 3 weeks and later (2.8%) was significantly lower ( < 0.05). In three cases, deoxyribonucleic acid was also found on the unaffected side in the initial phase of the disease, but detection on that side (18.9%) was significantly lower than on the affected side (83.8%) ( < 0.01). The number of copies of the herpes simplex virus-1 genome was large on the affected side and early after the onset of the disease. The reactivation of herpes simplex virus-1 on the affected side is involved as a pathogenic factor of Bell's Palsy. A reactivation of herpes simplex virus-1 may be generated even on the unaffected side in the early phase of the disease. Herpes simplex virus deoxyribonucleic acid was not detected in any of the examined specimens collected from the remaining 11 cases. The need for constant study to clarify other causative factors of Bell's Palsy remains.