Diagnostic parameters of modified two-tier testing in European patients with early Lyme disease.

Modified two-tier testing (MTTT) for Lyme borreliosis (i.e. confirmation with an EIA instead of an immunoblot) has been shown to have improved sensitivity compared with standard two-tier testing (STTT) in samples from American patients, without losing specificity. The current study assesses the sensitivity and specificity of various algorithms of MTTT in European patients with erythema migrans (EM) as a model disease for early Lyme borreliosis, and in appropriate controls. Four different immunoassays were used in the first tier, followed by either an immunoblot or the C6-EIA, or were used as standalone single-tier test. These tests were performed on consecutively collected sera of 228 Dutch patients with physician-diagnosed EM in the setting of general practice, 231 controls from the general population, and 50 controls with potentially cross-reactive antibodies. All the variants of MTTT that were studied had significantly higher sensitivity compared with their equivalent STTT, while retaining comparable specificity. Within the MTTT algorithms, classifying equivocal results as positive yielded better diagnostic parameters than classifying equivocal results as negative. The best diagnostic parameters were found using the Enzygnost-2 assay in the first tier, followed by a C6-ELISA in the second tier (sensitivity 77.6%, 95% CI 71.7-82.9; specificity 96.1%, 95% CI 92.7-98.2). This algorithm performed significantly better than the equivalent STTT algorithm in terms of sensitivity (p < 0.001), while maintaining comparable specificity (population controls p = 0.617). Our results show that MTTT can be a useful tool for the serodiagnosis of European patients with early Lyme borreliosis.

The diagnostic accuracy of serological tests for Lyme borreliosis in Europe: a systematic review and meta-analysis.

BACKGROUND: Interpretation of serological assays in Lyme borreliosis requires an understanding of the clinical indications and the limitations of the currently available tests. We therefore systematically reviewed the accuracy of serological tests for the diagnosis of Lyme borreliosis in Europe. METHODS: We searched EMBASE en MEDLINE and contacted experts. Studies evaluating the diagnostic accuracy of serological assays for Lyme borreliosis in Europe were eligible. Study selection and data-extraction were done by two authors independently. We assessed study quality using the QUADAS-2 checklist. We used a hierarchical summary ROC meta-regression method for the meta-analyses. Potential sources of heterogeneity were test-type, commercial or in-house, Ig-type, antigen type and study quality. These were added as covariates to the model, to assess their effect on test accuracy. RESULTS: Seventy-eight studies evaluating an Enzyme-Linked ImmunoSorbent assay (ELISA) or an immunoblot assay against a reference standard of clinical criteria were included. None of the studies had low risk of bias for all QUADAS-2 domains. Sensitivity was highly heterogeneous, with summary estimates: erythema migrans 50% (95% CI 40% to 61%); neuroborreliosis 77% (95% CI 67% to 85%); acrodermatitis chronica atrophicans 97% (95% CI 94% to 99%); unspecified Lyme borreliosis 73% (95% CI 53% to 87%). Specificity was around 95% in studies with healthy controls, but around 80% in cross-sectional studies. Two-tiered algorithms or antibody indices did not outperform single test approaches. CONCLUSIONS: The observed heterogeneity and risk of bias complicate the extrapolation of our results to clinical practice. The usefulness of the serological tests for Lyme disease depends on the pre-test probability and subsequent predictive values in the setting where the tests are being used. Future diagnostic accuracy studies should be prospectively planned cross-sectional studies, done in settings where the test will be used in practice.

A Dutch nationwide evaluation of serological assays for detection of Borrelia antibodies in clinically well-defined patients.

Numerous tests for the detection of antibodies against Borrelia burgdorferi are commercially available. Manufacturer-derived data invariably report a high sensitivity and specificity, but comparative studies demonstrate large differences in clinical practice, especially with regard to specificity. We retrospectively collected data from validation studies for B. burgdorferi antibody assays from 8 laboratories in the Netherlands. The total number of samples was 809. Samples were selected based on clinical and laboratory parameters. We included samples from patients with erythema migrans, acrodermatitis chronicum atrophicans, and neuroborreliosis; cross-reactivity controls; and healthy controls. Data are presented from 10 enzyme-linked immunosorbent assays and 5 immunoblots. For manifestations of B. burgdorferi infection with short disease duration, the positivity rate of the assays varied significantly. In patients with long disease duration, the positivity rate differed only marginally. In cross-reactivity controls, there was significant variation in the reactivity rate. The majority of false-positive reactions are of the IgM isotype.

[Small risk of developing Lyme borreliosis following a tick bite on Ameland: research in a general practice]. / Kleine kans op lymeborreliose na een tekenbeet op Ameland: onderzoek in een huisartsenpraktijk.

OBJECTIVE: To investigate the percentage of ticks infected with Borrelia burgdorferi on the Dutch North Sea island of Ameland, and the risk of developing Lyme disease following tick bite on the island. DESIGN: Prospective, observational. METHOD: Ticks were collected from patients who visited a general practitioner and were tested for the DNA of B. burgdorferi. After 6 months the patients were interviewed by phone using a standardised questionnaire. RESULTS: From 2004-2006, 216 ticks were collected from 167 persons. Most ticks were removed within 24 hours. In 44 ticks (20.4%) B. burgdorferi DNA was detected. Follow up information was available on 146 persons, 41 (28.1%) of whom had been bitten by a Borrelia-positive tick. None of the persons developed a typical erythema migrans. From the 13 persons (9%) reporting a non-specific redness of the skin (diameter less than 5 cm) at the site of the tick bite, 5 had been bitten by a positive tick and 8 by a negative tick. One patient bitten by a positive tick reported systemic symptoms related to Lyme borreliosis, namely fatigue, perspiration and joint ache, without local redness. CONCLUSION: The probability of developing Lyme borreliosis was low even though a relatively large percentage of the ticks collected were positive for B. burgdorferi. This is probably connected to the fact that in the majority of cases the tick had been removed within 24 hours.

Identification of a common HLA-DP4-restricted T-cell epitope in the conserved region of the respiratory syncytial virus G protein.

The cellular immune response to respiratory syncytial virus (RSV) is important in both protection and immunopathogenesis. In contrast to HLA class I, HLA class II-restricted RSV-specific T-cell epitopes have not been identified. Here, we describe the generation and characterization of two human RSV-specific CD4(+)-T-cell clones (TCCs) associated with type 0-like cytokine profiles. TCC 1 was specific for the matrix protein and restricted over HLA-DPB1*1601, while TCC 2 was specific for the attachment protein G and restricted over either HLA-DPB1*0401 or -0402. Interestingly, the latter epitope is conserved in both RSV type A and B viruses. Given the high allele frequencies of HLA-DPB1*0401 and -0402 worldwide, this epitope could be widely recognized and boosted by recurrent RSV infections. Indeed, peptide stimulation of peripheral blood mononuclear cells from healthy adults resulted in the detection of specific responses in 8 of 13 donors. Additional G-specific TCCs were generated from three of these cultures, which recognized the identical (n = 2) or almost identical (n = 1) HLA-DP4-restricted epitope as TCC 2. No significant differences were found between the capacities of cell lines obtained from infants with severe (n = 41) or mild (n = 46) RSV lower respiratory tract infections to function as antigen-presenting cells to the G-specific TCCs, suggesting that the severity of RSV disease is not linked to the allelic frequency of HLA-DP4. In conclusion, we have identified an RSV G-specific human T helper cell epitope restricted by the widely expressed HLA class II alleles DPB1*0401 and -0402. Its putative role in protection and/or immunopathogenesis remains to be determined.

Moderate local and systemic respiratory syncytial virus-specific T-cell responses upon mild or subclinical RSV infection.

Respiratory syncytial virus (RSV) infections are a major cause of severe respiratory disease in infants. It has been shown that there is an increased frequency of childhood wheezing in ex-bronchiolitic preteen children. This was postulated to be mediated by a vigorous virus-specific Th2 response influencing the further development of the immune system. Little is known about the possible role of the immune response to clinically mild RSV infections in this respect. We have studied the RSV-specific cellular immune response in infants with a laboratory-confirmed RSV upper respiratory tract infection (URTI; n = 13, mean age 12 months, range 2-22 months) in comparison with infants with non-RSV mediated URTI (n = 9, mean age 9.3 months, range 4-18 months) or infants with severe RSV bronchiolitis (n = 11, mean age 2.3 months, range 1-6 months). RSV-specific cytokine-producing cells were enumerated using the ELISPOT method in peripheral blood mononuclear cells and nasal brush T-cells, collected during the acute and convalescent phase of the infection. Mixed Th1 (IFN-gamma) and Th2 (IL-4 and IL-13) responses were detected in all three groups. Frequencies of RSV-specific T-cells were lower in both URTI groups than in the RSV bronchiolitis group, and not significantly different between the RSV URTI and the non-RSV URTI group. The absence of vigorous virus-specific Th2 responses upon mild RSV infection does not support the hypothesis that these infections influence the development of the immune system and that they predispose for the development of atopic disease.

Pathogenesis of RSV lower respiratory tract infection: implications for vaccine development.

Respiratory syncytial virus (RSV) infection is the most prevalent cause of severe respiratory disease in infants. It also causes considerable morbidity in older children and adults with underlying risk factors. RSV vaccine development has been complicated by the need to administer the vaccine at a very young age and by enhanced disease observed after vaccination with formalin inactivated RSV. For infants live attenuated vaccines, which may not be expected to predispose for vaccine induced enhanced pathology, hold the greatest promise. However, the balance between attenuation and immunogenicity appears to be delicate. For older risk groups, results with subunit vaccines are most promising.

HLA class I-restricted cytotoxic T-cell epitopes of the respiratory syncytial virus fusion protein.

Virus-specific cytotoxic T lymphocytes (CTL) play a major role in the clearance of respiratory syncytial virus (RSV) infection. We have generated cytotoxic T-cell clones (TCC) from two infants who had just recovered from severe RSV infection. These TCC were functionally characterized and used to identify HLA class I (B57 and C12)-restricted CTL epitopes of RSV.

G protein variation in respiratory syncytial virus group A does not correlate with clinical severity.

Respiratory syncytial virus group A strain variations of 28 isolates from The Netherlands collected during three consecutive seasons were studied by analyzing G protein sequences. Several lineages circulated repeatedly and simultaneously during the respective seasons. No relationships were found between lineages on the one hand and clinical severity or age on the other.

Type 1-like immune response is found in children with respiratory syncytial virus infection regardless of clinical severity.

The immunological response of infants younger than six months to infection with respiratory syncytial virus (RSV) was studied in relation to clinical severity. IL-6 and IL-8 were found more frequently and at higher levels in the plasma samples of more severely ill patients and no significant differences were found in the levels of cytokines differentiating between Type 1 and Type 2 responses. Cellular infiltrates in nasopharyngeal washings consisted mainly of polymorphonuclear granulocytes and monocytes. Eosinophils, IgE positive cells and tryptase positive cells were found sporadically. Analyses of RSV stimulated T cell cultures established from peripheral blood mononuclear cells, for intracellular and secreted cytokines showed that, irrespective of clinical severity, the responses were dominated by the production of IFN-gamma, and that only low levels of IL-4 and IL-10 were detectable. Collectively these data do not indicate an association between clinical severity and a Type 2-like T cell response.

Cross-reactive antibodies against GM2 and CMV-infected fibroblasts in Guillain-Barré syndrome.

OBJECTIVE: To investigate whether anti-GM2 antibodies in patients with Guillain-Barré syndrome (GBS) are induced by molecular mimicry with cytomegalovirus (CMV). BACKGROUND: Antibodies against ganglioside GM2 are frequently present in the serum from GBS patients with an antecedent infection with CMV. METHODS: The authors detected inhibition of anti-GM2 reactivity after incubation of GM2-reactive serum samples with fibroblasts infected with a GBS-associated CMV strain. Control sera consisted of GQ1b-reactive samples, and control antigens included uninfected fibroblasts and fibroblasts that were infected with other herpes viruses. RESULTS: Serum immunoglobulin M reactivity with GM2 was decreased in a dose-dependent manner after incubation with CMV-infected fibroblasts. Incubation of anti-GM2-positive serum samples with uninfected fibroblasts and fibroblasts infected with varicella zoster virus did not inhibit anti-GM2 reactivity, whereas this reactivity was slightly decreased after incubation with herpes simplex virus type 1 in one patient. Antibodies against ganglioside GQ1b did not react with CMV-infected fibroblasts. CONCLUSIONS: CMV-infected fibroblasts express gangliosidelike epitopes that recognize specifically anti-GM2 antibodies. These results support the hypothesis that antiganglioside antibodies in CMV-infected GBS patients are induced by molecular mimicry between GM2 and antigens that are induced by a CMV infection.

Risk factors for respiratory syncytial virus associated apnoea.

UNLABELLED: Respiratory syncytial virus (RSV) infections are characterized by upper or lower respiratory tract symptoms including bronchiolitis and pneumonia. Apnoea may be the first sign of disease in children with RSV infection. The aims of this study were the identification of independent risk factors for RSV associated apnoea and the prediction of the risk for mechanical ventilation in children with RSV associated apnoea. Medical records of children younger than 12 months of age admitted with RSV infection between 1992 and 1995 to the Sophia Children's Hospital, were reviewed. Demographic parameters, clinical features and laboratory parameters (SaO2, pCO2 and pH) were obtained upon admission and during hospitalization. Children with and without apnoea were compared using univariate and multivariate logistic and linear regression analysis. One hundred and eighty-five patients with RSV infection were admitted of whom 38 (21%) presented with apnoea. Patients with apnoea were significantly younger, had a significantly lower temperature, higher pCO2 and lower pH and had on chest radiographs also more signs of atelectasis. The number of patients admitted to the ICU because of mechanical ventilation and oxygen administration was significantly higher in children with RSV associated apnoea. Apnoea at admission was a strong predictor for recurrent apnoea. The relative risk for mechanical ventilation increased with the number of episodes of apnoea: 2.4 (95% CI 0.8-6.6) in children with one episode of apnoea (at admission) versus 6.5 (95% CI 3.3-12.9) in children with recurrent episodes of apnoea. CONCLUSIONS: Age below 2 months is the strongest independent risk factor for RSV associated apnoea. Apnoea at admission increases the risk for recurrent apnoea. The risk for mechanical ventilation significantly increases in children who suffer from recurrent apnoea.

A subtype-specific peptide-based enzyme immunoassay for detection of antibodies to the G protein of human respiratory syncytial virus is more sensitive than routine serological tests.

Peptides deduced from the central conserved region (residues 158 to 189) of protein G of human respiratory syncytial virus (HRSV) subtypes A and B were used as antigens in subtype-specific enzyme-linked immunosorbent assays (G-peptide ELISAs). These G-peptide ELISAs were compared with seven other serological assays to detect HRSV infection: ELISAs based on complete protein G, on fusion protein F, and on nucleoprotein N; a complement fixation assay; a virus neutralization test; and ELISAs for the detection of immunoglobulin A (IgA) or IgM antibodies specific for HRSV. In paired serum samples from patients with HRSV infection, more infections were diagnosed by the G-peptide ELISA (67%) than by all other serological tests combined (48%). Furthermore, for 16 of 18 patients (89%), the G-peptide ELISAs were able to differentiate between antibodies against HRSV subtypes A and B. This study shows that peptides corresponding to the central conserved region of the attachment protein G of HRSV can successfully be used as antigens in immunoassays. The G-peptide ELISA appeared to be more sensitive than conventional tests for the detection of HRSV antibody titer rises.

Respiratory syncytial virus specific serum antibodies in infants under six months of age: limited serological response upon infection.

The decline of maternal respiratory syncytial virus (RSV) specific serum antibodies was studied in 45 children during the first 6 months of life, using a virus neutralization assay and competition ELISAs measuring fusion protein and glycoprotein specific antibodies. In all children RSV neutralizing antibodies were demonstrated at birth, with titers ranging from 33 to 1382. The calculated mean half life of these antibodies was 26 days. Furthermore, in a group of 38 children with suspected RSV infection, all younger than 6 months of age on admission, the diagnostic value of serological assays was evaluated. In 32 children RSV infection was confirmed by virus isolation, direct immune fluorescence and RT-PCR. In 7 patients of this group a significant titer rise in virus neutralization assay was demonstrated. Six additional RSV infected children could be identified by showing the presence of RSV-specific IgM or IgA serum antibodies or by showing an increase in fusion protein or glycoprotein specific antibodies. All serological tests together identified 13 (41%) of the 32 RSV infected patients. It is concluded that in children of this age group, which represent the majority of patients hospitalized with RSV infections, serological assays not only have a limited diagnostic value but are of limited value for sero-epidemiological studies.

Local variability in respiratory syncytial virus disease severity.

Respiratory syncytial virus (RSV) lower respiratory tract infections are considered to be a serious disease in centres such as the Sophia Children's Hospital (Rotterdam, the Netherlands), but as more benign infections in others such as the Geneva Children's Hospital (Switzerland). To assess the clinical severity of RSV infections at the two sites, 151 infants primarily admitted with a virologically confirmed RSV infection were studied prospectively (1994-5) and retrospectively (1993-4) (55 infants in Geneva and 96 in Rotterdam). Parameters of RSV morbidity which were more severe in Rotterdam during the two winter seasons were apnoea (1.8 v 23.9%), the rate of admission to the intensive care unit (3.6 v 28.1%), mechanical ventilation (0 v 7.3%), and length of stay in hospital (6.8 v 9.1 days). In Geneva higher respiratory rates (59.2 v 51.2), more wheezing (65.5 v 28.8%), and more retractions (81.8 v 63.3%) were recorded. Fewer infants younger than 4 months (54.9 v 68.7%), but more breast fed infants (94.1 v 38.5%), were admitted in Geneva, although the morbidity parameters remained different after correction for these two variables in multivariate analyses. Thus unidentified local factors influence the pattern and severity of RSV infection and may affect the results of multicentre prophylactic and therapeutic studies.

Patient-to-patient spread of a single strain of Corynebacterium striatum causing infections in a surgical intensive care unit.

Over a 12-month period, Corynebacterium striatum strains were isolated from clinical specimens from 14 patients admitted to a surgical intensive care unit. These isolates were identical by morphology and biotype and displayed the same antibiogram. Ten isolates were found to be the sole possible pathogen. These 10 isolates were from six patients, three of whom had signs of infection at the time of positive culture. Further typing was performed by random amplification of polymorphic DNA analysis, by which all strains were identical and were found to differ to various degrees from reference strains and from isolates found in clinical samples from other wards. In a case-control study the only independent risk factor for acquiring the strain was intubation for longer than 24 h (odds ratio, 20.09; 95% confidence interval, 2.29 to 176.09). The same strain was isolated from surfaces and from air sampled in the direct vicinity of infected patients but never from surfaces or air in other places of the ward. The strain was not isolated from the ventilators. The strain was cultured from the hands of personnel attending to infected patients, but no long-term carriers were found among members of the hospital personnel, suggesting transient carriage only. We conclude that C. striatum can cause serious nosocomial infections in surgical intensive care unit patients and may spread from patient to patient via the hands of attending personnel.

Relationship between clinical severity of respiratory syncytial virus infection and subtype.

The relationship between clinical severity of respiratory syncytial virus (RSV) infection and distribution of subtype A or B was investigated. The data of 232 children, who were admitted with RSV infection or diagnosed in the outpatient department of the Sophia Children's Hospital, Rotterdam between 1992 and 1995, were studied. The diagnosis of RSV was confirmed by a direct immunofluorescence assay. Subtyping was performed by an indirect immunofluorescence assay using specific monoclonal antibodies. Gender, age at diagnosis, gestational age and birth weight, the presence of underlying diseases, feeding difficulties, the presence of wheezing and retractions, respiratory rate, temperature, clinical diagnosis at presentation, oxygen saturation (SaO2), carbon dioxide tension (PCO2), and pH, characteristics of hospitalisation, and the need for mechanical ventilation were observed. Analysis was performed on data from all patients diagnosed with RSV infection in the period between 1992 and 1995 spanning three RSV seasons, and separately on the RSV season 1993-4. The outcome of the three year analysis (150 (64.7%) subtype A v 82 (35.3%) subtype B) was compared with the outcome of the season 1993-4, a mixed epidemic with 37 (60.7%) subtype A and 24 (39.3%) subtype B isolates. None of the variables observed in the season 1993-4 differed significantly between RSV subtype A and B. Similar results were obtained from the analysis in the period 1992 until 1995, with the exception of PCO2 (a higher PCO2 was found in subtype A, p < 0.001) and retractions (more retractions were noted in patients with subtype A, p = 0.03). After correcting for possible confounders using regression analysis, these differences were not significant anymore. The data indicate that there is no relationship between clinical severity of RSV infection and subtype.

Type-specific serologic diagnosis of respiratory syncytial virus infection, based on a synthetic peptide of the attachment protein G.

Peptides deduced from the central hydrophobic region (residues 158-189) of the G protein of bovine and ovine respiratory syncytial virus (RSV) and of human RSV subtypes A and B were synthesized. These peptides were used to develop ELISAs to measure specifically antibodies against these types and subtypes of RSV. We have evaluated the bovine RSV-G peptide in both an indirect ELISA and in a blocking ELISA. Specificity and sensitivity, relative to a routine diagnostic ELISA that detects antibodies against the RSV F-protein in bovine sera, were 98% and 92% respectively for the indirect peptide-based ELISA, and 98% and 98% for the blocking peptide-based ELISA. In paired serum samples, rises in antibody titer were detected more frequently with the indirect peptide-based ELISA than with the routine F-ELISA. Furthermore, the peptide-based G-ELISAs were able to differentiate between antibodies against BRSV and HRSV, and between those against BRSV and ORSV. In addition, the indirect peptide-based ELISA was selective for HRSV subtype A and B antibodies. This study shows that peptides, corresponding to the central hydrophobic region of the attachment protein G of several RSVs, can be used successfully as antigens in highly specific and sensitive immunoassays.

Detection of respiratory syncytial virus by RNA-polymerase chain reaction and differentiation of subgroups with oligonucleotide probes.

The polymerase chain reaction (RNA-PCR) was used for specific detection of respiratory syncytial virus (RSV) genomes in clinical specimens. A set of primers was selected from conserved regions of the 1B and N genes for detection of both subgroups. The primers were found to be RSV specific, all RSV strains generated a 218 bp product, and no RSV specific amplified product was obtained when nucleic acids from a variety of micro-organisms from the respiratory tract were subjected to the RNA-PCR. We took advantage of the sequence heterogeneity of the amplified products to discriminate between the A and B strains by hybridisation with subgroup specific oligonucleotide probes. This additional hybridisation assay increased the sensitivity of the RNA-PCR tenfold. The RNA-PCR was tested on clinical specimens from children with symptoms of an infection of the respiratory tract. The results were compared with isolation of RSV in cell culture and direct immunofluorescence. From 93 specimens tested, 31 were found positive by all three techniques. Six additional positive results were detected using RNA-PCR. From these 37 RSV positive specimens 33 (92%), including all 6 additional positives, were subgroup A and only 4 were subgroup B strains. Thus, the RNA-PCR is a specific and sensitive technique for the detection and subgroup classification of RSV genomes.