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PubMed2004

Linkage arrangement of Na,K-ATPase genes in the tetraploid-derived genome of the rainbow trout (Oncorhynchus mykiss).

As part of our efforts to characterize Na,K-ATPase isoforms in salmonid fish, we investigated the linkage arrangement of genes coding for the alpha and beta-subunits of the enzyme complex in the tetraploid-derived genome of the rainbow trout (Oncorhynchus mykiss). Genetic markers were developed from four of five previously characterized alpha-subunit isoforms (alpha1b, alpha1c, alpha2 and alpha3) and four expressed sequence tags derived from yet undescribed beta-subunit isoforms (beta1a, beta1b, beta3a and beta3b). Sex-specific linkage analysis of polymorphic loci in a reference meiotic panel revealed that Na,K-ATPase genes are generally dispersed throughout the rainbow trout genome. A notable exception was the colocalization of two alpha-subunit genes and one beta-subunit gene on linkage group RT-12, which may thus share a conserved orthologous segment with linkage group 1 in zebrafish (Danio rerio). Consistent with previously reported homeologous relationships among the chromosomes of the rainbow trout, primers designed from the alpha3-isoform detected a pair of duplicated genes on linkage groups RT-27 and RT-31. Similarly, the evolutionary conservation of homeologous regions on linkage groups RT-12 and RT-16 was further supported by the map localization of gene duplicates for the beta1b isoform. The detection of homeologs within each gene family also raises the possibility that novel isoforms may be discovered as functional duplicates.

Animals↗

PubMed2005

Rapid genotyping of methicillin-resistant Staphylococcus aureus (MRSA) isolates using miniaturised oligonucleotide arrays.

This study evaluated a DNA oligonucleotide array that recognised 38 different Staphylococcus aureus targets, including all relevant resistance determinants and some toxins and species-specific controls. A new method for labelling sample DNA, based on a linear multiplex amplification that incorporated biotin-labelled dUTP into the amplicon, was established, and allowed detection of hybridisation of the amplicons to the array with an enzymic precipitation reaction. The whole assay was validated by hybridisations with a panel of reference strains and cloned specific PCR products of all targets. To evaluate performance under routine conditions, the assay was used to test 100 methicillin-resistant S. aureus (MRSA) isolates collected from a university hospital in Saxony, Germany. The results showed a high correlation with conventional susceptibility data. The ermA and ermC macrolide resistance genes were found in 40% and 32% of the isolates, respectively. The most prevalent aminoglycoside resistance gene was aphA3 (57% of the isolates), followed by aacA-aphD (29%) and aadD (29%); tet genes, mupR and dfrA were rare. There were no isolates with van genes or genes involved in resistance to quinupristin-dalfopristin. Enterotoxins were detected in 27% of the isolates. Genes encoding Panton-Valentine leukocidin, toxic shock syndrome toxin and exfoliative toxins were not found. The DNA array facilitated rapid and reliable detection of resistance determinants and toxins under conditions used in a routine laboratory and has the potential to be used for array-based high-throughput screening.

DNA, Bacterial↗

PubMed1995

Can penicillins and other beta-lactam antibiotics be used to treat tuberculosis?

An increase in the number of tuberculosis cases caused by multiple-drug-resistant strains of Mycobacterium tuberculosis has stimulated search for new antituberculous agents. Beta-lactam antibiotics, traditionally regarded as ineffective against tuberculosis, merit consideration. Four major penicillin-binding proteins (PBPs) with approximate molecular sizes of 94, 82, 52, and 37 kDa were detected by fluorography of [3H]penicillin-radiolabeled membrane proteins prepared from M. tuberculosis H37Ra. The presence of membrane-associated beta-lactamase precluded the use of membranes for assaying the binding affinities of beta-lactam antibiotics. Therefore, ampicillin affinity chromatography was used to purify these four PBPs from crude membranes in order to assay the binding affinities of beta-lactam antibiotics. Ampicillin, amoxicillin, and imipenem, beta-lactam antibiotics previously reported to be active in vitro against M. tuberculosis, bound to M. tuberculosis PBPs at therapeutically achievable concentrations. Binding of the 94-, 82-, and 52-kDa PBPs, but not the 37-kDa PBP, was associated with antibacterial activity, suggesting that these PBPs are the critical targets. Studies of mycobacterial cell wall permeability, which was assayed with a panel of reference cephalosporins and penicillins with different charge positivities, indicated that the rate of penetration of beta-lactam antibiotics to the target PBPs could not account for resistance. Resistance could be reversed with the beta-lactamase inhibitors clavulanate or sulbactam or could be circumvented by the use of a beta-lactamase-stable drug, imipenem, indicating that mycobacterial beta-lactamase, probably in conjunction with slow penetration, is a major determinant of M. tuberculosis resistance to beta-lactam antibiotics. These findings confirm in vitro data that M. tuberculosis is susceptible to some beta-lactam antibiotics. Further evaluation of these drugs for the treatment of tuberculosis in animal models and in clinical trials is warranted.

Animals↗

PubMed1987

Antigenic distinctiveness, heterogeneity, and relationships of Methanothrix spp.

A detailed immunologic analysis of Methanothrix soehngenii Opfikon (the type species of the genus), Methanothrix sp. strain CALS-1, and Methanothrix concilii GP6 was performed. A variety of poly- and monoclonal antibody probes for a comprehensive panel of reference organisms were used to determine immunogenicity, antigenicity, and relationships. The three organisms are antigenically distinct but interrelated, forming an immunologically cohesive group, weakly related to methanosarcinae. A prominent feature of the organisms was heterogeneity characterized by antigenic diversity and compartmentation, the latter particularly evident in M. soehngenii Opfikon, which was examined more thoroughly. The complexity of the antigenic profile of this strain and the heterogeneity of the group suggest a high degree of phenotypic diversification within the genus.

Animals↗

PubMed2006

Sensitivities of four new commercial hepatitis B virus surface antigen (HBsAg) assays in detection of HBsAg mutant forms.

Mutations in hepatitis B virus surface antigen (HBsAg) involving amino acid substitution within the immunodominant "a" determinant may affect the performance of commercial HBsAg assays. The performances of four HBsAg assays that recently received Conformité Européene marking, Advia Centaur HBsAg (Bayer), Monolisa HBsAg Ultra (Bio-Rad), Liaison HBsAg (Dia Sorin), and Vidas HBsAg Ultra (bioMérieux), were compared with that of the routinely used HBsAg assay AxSYM HBsAg V2 (Abbott). Assays were evaluated for (i) analytical sensitivity performance with a national reference HBsAg panel (including 10 samples with calibrated HBsAg concentrations from 0.04 to 2.24 ng/ml) and (ii) the detection of HBsAg mutants by studying a panel of 35 HBsAg mutants (23 collected from patients and 12 recombinant mutants). The limits of detection of these assays were <0.15 ng/ml (from 0.089 to 0.121 ng/ml). The sensitivity performances for mutant virus detection varied, ranging from 37.1% to 91.4%. The lack of detection of these mutants by commercial assays was probably due to the epitope recognition of the anti-HBs assay reagents in the capture phase and in the conjugates. The prevalence and clinical impact of HBsAg mutants are under investigation. However, the manufacturers must be vigilant in the design of the assays in order to reduce the risk of missing a broad range of described S gene mutants.

Hepatitis B Surface Antigens↗

PubMed1993

Detection of antibodies against equine herpesvirus types 1 and 4 by using recombinant protein derived from an immunodominant region of glycoprotein B.

The N-terminal fragment comprising residues +1 to +50 (gB1-50) of equine herpesvirus type 1 (EHV-1) glycoprotein B was expressed as a glutathione S-transferase fusion protein in Escherichia coli. Recombinant gB1-50 (rgB1-50) was recognized in immunoblots by sera from rabbits immunized with EHV-1 and by convalescent-phase sera from horses with natural EHV-1 infections. An enzyme-linked immunosorbent assay (ELISA) for monitoring antibody levels against EHV-1 was developed by using rgB1-50, and its specificity was assessed with a panel of reference antisera against other equine viruses. A specific cross-reaction was detected with EHV-4, which was confirmed by inhibition ELISA. Convalescent-phase sera from horses with natural EHV-1 or EHV-4 infections possessed antibody titers against rgB1-50 ranging from 1:2,000 to 1:64,000, indicating the presence of an immunodominant antigenic site. The study demonstrated the potential application of rgB1-50 as a diagnostic antigen and highlights the glutathione S-transferase fusion system as a simple and effective method of producing purified milligram quantities of antigen.

Amino Acid Sequence↗

PubMed2001

Development of an env gp41-based heteroduplex mobility assay for rapid human immunodeficiency virus type 1 subtyping.

The gp120 region of the human immunodeficiency virus type 1 (HIV-1) envelope (env) gene exhibits a high level of genetic heterogeneity across the group M subtypes. The heteroduplex mobility assay (HMA) has successfully been used to assign subtype classifications, but C2V5 primers often fail to amplify African strains. We developed an env gp41-based HMA for which the target sequence is amplified with highly conserved gp41 primers, known to efficiently amplify nucleic acids from HIV-1 group M, N, and O viruses. By using gp41 from a new panel of reference strains, the subtype assignments made by our modified HMA were concordant with those obtained by sequencing and phylogenetic analysis of 34 field strains from 10 countries representing subtypes A to G. Testing of field strains from Nigeria further demonstrated the utility of this modified assay. Of 28 samples, all could be amplified with gp41 primers but only 17 (60.7%) could be amplified with the standard C2V5 primers. Therefore, gp41-based HMA can be a useful tool for the rapid monitoring of prevalent subtypes in countries with divergent strains of circulating HIV-1.

DNA, Viral↗

PubMed2003

Applicability of a real-time quantitative PCR assay for diagnosis of respiratory syncytial virus infection in immunocompromised adults.

Respiratory syncytial virus (RSV) accounts for the majority of respiratory virus infections, producing high mortality rates in immunocompromised patients with hematologic malignancies. The available methods for the rapid detection of RSV by antigen detection or PCR either lack sensitivity, require complex laboratory manipulation, or have not been evaluated in this patient population. To assess the applicability of a TaqMan-based real-time PCR technique for the detection of RSV A and B in immunocompromised adults, we developed a rapid, sensitive detection method that simultaneously detects RSV A and B and can be applied in routine diagnostics. The specificity of the assay was assessed using a panel of reference strains of other respiratory viruses and RSV. Electron microscopy-counted stocks of RSV A and B were used to develop a quantitative PCR format. Eleven copies of viral RNA could be detected for RSV A strain Long, and 14 copies could be detected for RSV B strain 9320, corresponding to 50% tissue culture infective doses of 0.86 and 0.34, respectively. The assay was evaluated on 411 combined nose and throat swabs derived from immunocompromised adults with or without signs of respiratory tract infection. The diagnostic efficacy of the TaqMan PCR determined on the clinical samples showed that this real-time PCR technique was substantially more sensitive than the combination of conventional viral culture and shell vial culture. None of the clinical specimens derived from patients without signs of respiratory illness were found to be positive for RSV by real-time TaqMan PCR.

Adult↗

PubMedDate not supplied

A mutation in the MATP gene causes the cream coat colour in the horse.

In horses, basic colours such as bay or chestnut may be partially diluted to buckskin and palomino, or extremely diluted to cream, a nearly white colour with pink skin and blue eyes. This dilution is expected to be controlled by one gene and we used both candidate gene and positional cloning strategies to identify the "cream mutation". A horse panel including reference colours was established and typed for different markers within or in the neighbourhood of two candidate genes. Our data suggest that the causal mutation, a G to A transition, is localised in exon 2 of the MATP gene leading to an aspartic acid to asparagine substitution in the encoded protein. This conserved mutation was also described in mice and humans, but not in medaka.

Animals↗

PubMed2006

Selection of a set of reliable reference genes for quantitative real-time PCR in normal equine skin and in equine sarcoids.

BACKGROUND: Real-time quantitative PCR can be a very powerful and accurate technique to examine gene transcription patterns in different biological conditions. One of the critical steps in comparing transcription profiles is accurate normalisation. In most of the studies published on real-time PCR in horses, normalisation occurred against only one reference gene, usually GAPDH or ACTB, without validation of its expression stability. This might result in unreliable conclusions, because it has been demonstrated that the expression levels of so called "housekeeping genes" may vary considerably in different tissues, cell types or disease stages, particularly in clinical samples associated with malignant disease. The goal of this study was to establish a reliable set of reference genes for studies concerning normal equine skin and equine sarcoids, which are the most common skin tumour in horses. RESULTS: In the present study the gene transcription levels of 6 commonly used reference genes (ACTB, B2M, HPRT1, UBB, TUBA1 and RPL32) were determined in normal equine skin and in equine sarcoids. After applying the geNorm applet to this set of genes, TUBA1, ACTB and UBB were found to be most stable in normal skin and B2M, ACTB and UBB in equine sarcoids. CONCLUSION: Based on these results, TUBA1, ACTB and UBB, respectively B2M, ACTB and UBB can be proposed as reference gene panels for accurate normalisation of quantitative data for normal equine skin, respectively equine sarcoids. When normal skin and equine sarcoids are compared, the use of the geometric mean of UBB, ACTB and B2M can be recommended as a reliable and accurate normalisation factor.

Animals↗

PubMed1999

Early detection and accurate description of extent of metastatic bone disease in breast cancer with fluoride ion and positron emission tomography.

PURPOSE: Previous studies have shown that bone metastases are revealed by magnetic resonance imaging (MRI) or bone marrow scintigraphy several months before they are visible by conventional bone scintigraphy (BS). We present a new approach for detecting bone metastases in patients with breast cancer. We compared findings obtained with fluoride ion (F-18) and positron emission tomography (PET) with those obtained with conventional BS. PATIENTS AND METHODS: Thirty-four breast cancer patients were prospectively examined using F-18-PET and conventional BS. F-18-PET and BS were performed within 3 weeks of each other. Metastatic bone disease was previously known to be present in six patients and was suspected (bone pain or increasing levels of tumor markers, Ca(2+), alkaline phosphatase) in 28 patients. Both imaging modalities were compared by patient-by-patient analysis and lesion-by-lesion analysis, using a five-point scale for receiver operating characteristic (ROC) curve analysis. A panel of reference methods was used, including MRI (28 patients), planar x-ray (17 patients), and spiral computed tomography (four patients). RESULTS: With F-18-PET, 64 bone metastases were detected in 17 patients. Only 29 metastases were detected in 11 patients with BS. As a result of F-18-PET imaging, clinical management was changed in four patients (11.7%). For F-18-PET, the area under the ROC curve was 0.99 on a lesion basis (for BS, it was 0.74; P <.05) and 1.00 on a patient basis (for BS, it was 0.82; P <.05). CONCLUSION: F-18-PET demonstrates a very early bone reaction when small bone marrow metastases are present, allowing accurate detection of breast cancer bone metastases. This accurate detection has a significant effect on clinical management, compared with the effect on management brought about by detection with conventional BS.

Adult↗

PubMed1999

Sensitivity in detecting osseous lesions depends on anatomic localization: planar bone scintigraphy versus 18F PET.

UNLABELLED: Radionuclide bone scanning (RNB) is considered to be the most practical screening technique for assessing the entire skeleton for skeletal metastases. However, RNB has been shown to be of lower sensitivity than MRI and CT in detecting osteolytic metastases. A prospective study was designed to evaluate the accuracy of planar RNB versus tomographic bone imaging with 18F-labeled NaF and PET (18F PET) in detecting osteolytic and osteoblastic metastases and its dependency on their anatomic localization. METHODS: Forty-four patients with known prostate, lung or thyroid carcinoma were examined with both planar RNB and 18F PET. A panel of reference methods including MRI of the spine, 1311 scintigraphy, conventional radiography and spiral CT was used as the gold standard. RNB and 18F PET were compared by a lesion-by-lesion analysis using a five-point score for receiver operating characteristic (ROC) curve analysis. RESULTS: 18F PET showed 96 metastases (67 of prostate carcinoma and 29 of lung or thyroid cancer), whereas RNB revealed 46 metastases (33 of prostate carcinoma and 13 of lung or thyroid cancer). All lesions found with RNB were also detected with 18F PET. Compared with 18F PET and the reference methods, RNB had a sensitivity of 82.8% in detecting malignant and benign osseous lesions in the skull, thorax and extremities and a sensitivity of 40% in the spine and pelvis. The area under the ROC curve was 0.99 for 18F PET and 0.64 for RNB. CONCLUSION: 18F PET is more sensitive than RNB in detecting osseous lesions. With RNB, sensitivity in detecting osseous metastases is highly dependent on anatomic localization of these lesions, whereas detection rates of osteoblastic and osteolytic metastases are similar. Higher detection rates and more accurate differentiation between benign and malignant lesions with 18F PET suggest the use of 18F PET when possible.

Bone Neoplasms↗

PubMed1982

Expression of type C viral glycoproteins on P815 cells: higher expression of Mr 70,000 glycoprotein-containing glycoprotein on immunogenic variants.

Cells from P815 mastocytoma, a methylcholanthrene-induced tumor, were investigated for the presence of type C viral proteins on their surface. Little or no precipitation of purified Rauscher murine leukemia virus Mr 70,000 glycoprotein was observed with sera of mice immunized with P815 cells. However, a significant precipitation was obtained with sera from syngeneic or allogeneic mice immunized with P815 tumor cell variants obtained by mutagenesis. This difference was not detected when the sera were tested for precipitation of a pure Rauscher murine leukemia virus Mr 30,000 protein. The positive sera also precipitated a Mr 90,000 glycoprotein present on the membrane of all P815 cells. This glycoprotein was shown to contain endogenous ecotropic murine leukemia virus Mr 70,000 glycoprotein. On the membrane, a separate glycoprotein with a molecular weight of 90,000 containing gag gene products was also detected with a panel of reference antibodies. The level of glycoprotein containing Mr 70,000 glycoprotein on the cell membrane of the mutagenized cell variants was higher compared to the original P815 cells. The level of expression of the glycosylated gag precursor was the same on the original P815 cells and on the mutagenized cell variants.

Animals↗

PubMed1993

Localization of juvenile, but not late-infantile, neuronal ceroid lipofuscinosis on chromosome 16.

The neuronal ceroid lipofuscinoses (NCL) are a group of progressive neurodegenerative disorders characterized by the deposition of autofluorescent proteinaceous fingerprint or curvilinear bodies. We have found that CLN3, the gene underlying the juvenile form of NCL, is very tightly linked to the dinucleotide repeat marker D16S285 on chromosome 16. Integration of D16S285 into the genetic map of chromosome 16 by using the Centre d'Etude du Polymorphisme Humain panel of reference pedigrees yielded a favored marker order in the CLN3 region of qtel-D16S150-.08-D16S285-.04-D16S148-.02-D16S 67-ptel. The most likely location of the disease gene, near D16S285 in the D16S150-D16S148 interval, was favored by odds of greater than 10(4):1 over the adjacent D16S148-D16S67 interval, which was recently reported as the minimum candidate region. Analysis of D16S285 in pedigrees with late-infantile NCL virtually excluded the CLN3 region, suggesting that these two forms of NCL are genetically distinct.

Adolescent↗

PubMed2004

Independent double reading of screening mammograms in The Netherlands: effect of arbitration following reader disagreements.

PURPOSE: To prospectively determine the value of arbitration by a panel of radiologists when two radiologists performing independent readings of screening mammograms do not reach a consensus about referral. MATERIALS AND METHODS: The study population consisted of women who participated in the Dutch Nationwide Breast Cancer Screening Program, in which biennial screening is offered to women aged 50-75 years. An arbitration panel of three radiologists assessed those screening mammograms for which two screening radiologists did not reach a consensus about referral necessity. Women were referred for further analysis if at least one arbitration panel radiologist considered referral to be necessary. RESULTS: The two screening radiologists agreed on the recommendation for referral of 498 (0.8%) of 65,779 screened women and on the recommendation for no referral of 64,949 (98.7%) women. They initially disagreed about the referral in 332 (0.5%) cases. After a mutual consultation, disagreement persisted regarding 183 (0.3%) mammograms. The arbitration panel referred 89 of these cases for further analysis, which revealed cancer in 20 (22%) cases. In three (3%) of the 94 cases that were not referred by the panel, breast cancer was detected at the site of previously discrepant mammographic findings seen at subsequent screening performed 2 years later. If all 183 discrepant cases had been referred, the referral rate would have increased from 0.8% to 0.9% at subsequent (incident) screenings and from 1.5% to 1.7% at initial screenings. In addition, at subsequent screenings, the number of cancers detected per 1,000 women screened would have increased from 4.4 to 4.5. CONCLUSION: Mammograms with discrepant findings constitute a very important subset of screening mammograms. All lesions that are subsequently proved to be malignant may not be detected with panel arbitration.

Aged↗

PubMed2003

Renewable standard reference material for the detection of TP53 mutations.

BACKGROUND: Numerous DNA-based tests are currently in use or under development for the detection of mutations associated with disease. Most of the current methods use PCR amplification technologies and detection after separation or chromatography of the products. We have developed a panel of standard reference materials consisting of 12 plasmid clones containing a 2.0 kb region of the TP53 gene, including exons 5-9. Eleven of these clones contain a single mutation within the mutational hot spots of the TP53 gene, the twelfth is wild-type in this region of the gene. The mutations are amino acid (aa) 128: C to T; aa 175: G to A; aa 237: T to C; aa 245: G to A; aa 248: C to T; aa 248: G to A; aa 249: G to T; aa 273: C to T; aa 273: G to A; aa 282: C to T; and aa 328: T to C. These standard reference materials (SRMs), created by site-directed mutagenesis of wild-type TP53 from a human cell line, include the specific mutations most commonly found to be associated with cancer. Their use will improve disease detection by serving as validation materials to monitor errors in measurement methods, including PCR amplification, amplicon separation, and data analysis from different technology platforms. METHODS AND RESULTS: The single point mutations of the panel were validated by capillary electrophoresis single-strand conformational polymorphism analysis, denaturing gradient gel electrophoresis, and denaturing high-performance liquid chromatography, as well as full sequence analysis of both DNA strands of the cloned material. For both heteroduplex analysis methods, the presence of the mutations was resolved for each SRM. CONCLUSION: The generation of a standard TP53 reference panel and demonstration that the panel can successfully validate mutation detection across different mutation scanning technology platforms. Hence, this panel functions as an SRM to normalize results obtained from different laboratories using different techniques.

Base Sequence↗

PubMed1998

Comparison of a novel, inhibitor-potentiated disc-diffusion test with other methods for the detection of extended-spectrum beta-lactamases in Escherichia coli and Klebsiella pneumoniae.

A novel, inhibitor-potentiated disc-diffusion test for detecting extended-spectrum beta-lactamases (ESBLs) in bacteria was evaluated. This test uses the principle of augmentation (by > or = 10 mm) of inhibition zones produced by ceftazidime, cefotaxime, ceftriaxone or aztreonam discs on Mueller-Hinton agar supplemented with clavulanate (4 mg/L). The test was initially compared with the double-disc synergy test, Kirby-Bauer disc-diffusion test and Etest ESBL screen with a panel of 45 reference strains with known resistance profiles. This panel consisted of 27 ESBL-positive Escherichia coli strains expressing 14 Bush group 2be enzymes and 18 other E. coli and Klebsiella pneumoniae strains (14 non-ESBL beta-lactamase producers and four non-beta-lactamase producers). The Kirby-Bauer disc-diffusion test was the least sensitive method: 11-44% of the ESBL-positive control strains were misclassified as susceptible to ceftazidime, cefotaxime, ceftriaxone or aztreonam when interpreted by National Committee for Clinical Laboratory Standards (NCCLS) criteria. The sensitivities of the inhibitor-potentiated disc-diffusion test, the double-disc synergy test (when discs were 25 or 30 mm apart) and the Etest ESBL screen (with a breakpoint of > 4-fold reduction in ceftazidime MIC in the presence of clavulanate) were 100%, 96% and 89-96%, respectively. The inhibitor-potentiated disc-diffusion test was further evaluated with 81 E. coli and K. pneumoniae clinical isolates, which were identified as putative ESBL-producers by the double-disc synergy test. For these isolates, the sensitivity of both the inhibitor-potentiated disc-diffusion test and the Etest ESBL screen was 100%. In conclusion, the inhibitor-potentiated disc-diffusion test is a sensitive, convenient and inexpensive method of screening for ESBLs in E. coli and K. pneumoniae isolates, with potential for incorporation into routine clinical laboratory service.

Anti-Bacterial Agents↗

PubMed2006

European seroepidemiology network 2: Standardisation of assays for seroepidemiology of varicella zoster virus.

BACKGROUND: The aim of the European Sero-Epidemiology Network (ESEN2) is to harmonise the serological surveillance of vaccine-preventable diseases in Europe. OBJECTIVE: To allow comparison of antibody prevalence in different countries by standardising results into common units. STUDY DESIGN: For varicella zoster virus (VZV), a reference laboratory established a panel of 148 samples, characterised by indirect enzyme-immunoassay (ELISA), indirect immunofluorescence, and complement fixation test. Fifty-seven samples were also studied by the fluorescence antibody to membrane antigen test. The geometric mean of the antibody activity (GMAA) obtained from four ELISA determinations was used to characterise each sample of the panel as positive (GMAA: >100 mIU/ml), equivocal (GMAA: 50-100 mIU/ml) or negative (GMAA: <50 mIU/ml) for antibody to VZV (anti-VZV). Thirteen laboratories, using five different ELISA tests, tested the panel. RESULTS: Agreement with the reference laboratory was above 85% in all cases, and the R(2) values obtained from regression analysis of the quantitative results were always higher than 0.87. Finally, the regression equations could be used to convert national values into a common unitage. CONCLUSION: This study confirmed that results for anti-VZV obtained by different ELISA methods can be converted into common units, enabling the comparison of the seroprevalence profiles obtained in the participant countries.

Antibodies, Viral↗