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The diagnosis of Lyme neuroborreliosis (LNB) is based on neurological symptoms, cerebrospinal fluid (CSF) pleocytosis, and intrathecally produced Borrelia-specific antibodies. In most cases, the presence of intrathecally produced Borrelia-specific antibodies is determined by using an enzyme-linked immunosorbent assay (ELISA). The edge effect is a known phenomenon in ELISAs and can negatively influence the assay reproducibility and repeatability, as well as index calculations of sample pairs which are tested in the same run. For LNB diagnostics, an index calculation is used for which the relative amounts of Borrelia-specific antibodies in CSF and serum are measured to calculate a CSF/serum quotient, which is needed to calculate the Borrelia-specific antibody index (AI). The presence of an edge effect in an ELISA used for LNB diagnostics may thus have implications. In this study, we investigated the intra-assay variation of the commercial Enzygnost Lyme link VlsE/IgG ELISA used for LNB diagnostics and showed the presence of an edge effect. Minor adaptations in the ELISA protocol decreased this effect. The adapted protocol was subsequently used to test 149 CSF-serum pairs of consecutive patients received in a routine diagnostic laboratory. By simulation, we showed that, if the standard protocol would have been used, then the edge effect for this study population could have resulted in 15 (10.1%) false-pathological and two (1.3%) false-normal Borrelia-specific IgG AIs. Thus, the observed edge effect can lead to inaccurate LNB diagnoses. Our study underlines that the edge effect should be investigated when ELISAs are implemented in routine diagnostics, as this phenomenon can occur in any ELISA.

Lyme disease is a common multi-system disease caused by infection with a tick-transmitted spirochete, Borrelia burgdorferi and related Borrelia species. The monoglycosylated diacylglycerol known as B. burgdorferi glycolipid II (BbGL-II) is a major target of antibodies in sera from infected individuals. Here we show that CD1b presents BbGL-II to human T cells and that the T cell receptor (TCR) mediates the recognition. However, we did not detect increased frequency of CD1b-BbGL-II binding T cells in the peripheral blood of Lyme disease patients compared to controls. Unexpectedly, mapping the T cell specificity for BbGL-II-like molecules using tetramers and activation assays revealed a concomitant response to CD1b-expressing antigen presenting cells in absence of BbGL-II. Further, among all major classes of self-lipid tested, BbGL-II responsive TCRs show strong cross-reactivity to diacylglycerol, a self-lipid antigen with structural similarities to BbGL-II. Extending prior work on MHC and CD1b, CD1c, and CD1d proteins, this study provides evidence for cross-reactive CD1b-restricted T cell responses to bacterial and self-antigens, and identifies chemically defined targets for future discovery of self and foreign antigen cross-reactive T cells. This article is protected by copyright. All rights reserved.

A DNA isolation and purification method is described that produced DNA free of inhibitory substances in 148 of the 159 analyzed fecal samples. The polymerase chain reaction (PCR) product from a sensitive single-tube nested PCR that amplifies a part of an oocyst protein was used to characterize Cryptosporidium parvum genotypes by a simple restriction analysis. Genotype 1 was solely detected in human-derived oocysts, genotype 2 was present in both animal and human-derived oocysts. The ratio between both genotypes in humans in The Netherlands varied markedly between samples obtained during a period of augmented cases of cryptosporidiosis in the western part of the country and randomly selected samples from gastroenteritis patients. Sequence analysis of a 581-bp fragment from the nested PCR product revealed 12 nucleotide substitutions between the two genotypes. Sequences from isolates in each genotype group were identical.

Background Bordetella pertussis is the causative agent of human whooping cough (pertussis) and is particularly severe in infants. Despite worldwide vaccinations, whooping cough remains a public health problem. A significant increase in the incidence of whooping cough has been observed in many countries since the 1990s. Several reasons for the re-emergence of this highly contagious disease have been suggested. A particularly intriguing possibility is based on evidence indicating that pathogen adaptation may play a role in this process. In an attempt to gain insight into the genomic make-up of B. pertussis over the last 60 years, we used an oligonucleotide DNA microarray to compare the genomic contents of a collection of 171 strains of B. pertussis isolates from different countries. Results The CGH microarray analysis estimated the core genome of B. pertussis, to consist of 3,281 CDSs that are conserved among all B. pertussis strains, and represent 84.8% of all CDSs found in the 171 B. pertussis strains. A total of 64 regions of difference consisting of one or more contiguous CDSs were identified among the variable genes. CGH data also revealed that the genome size of B. pertussis strains is decreasing progressively over the past 60 years. Phylogenetic analysis of microarray data generated a minimum spanning tree that depicted the phylogenetic structure of the strains. B. pertussis strains with the same gene content were found in several different countries. However, geographic specificity of the B. pertussis strains was not observed. The gene content was determined to highly correlate with the ptxP-type of the strains. Conclusions An overview of genomic contents of a large collection of isolates from different countries allowed us to derive a core genome and a phylogenetic structure of B. pertussis. Our results show that B. pertussis is a dynamic organism that continues to evolve.

Background Whooping cough caused by Bordetella pertussis in humans, is re-emerging in many countries despite vaccination. Several studies have shown that significant shifts have occurred in the B. pertussis population resulting in antigenic divergence between vaccine strains and circulating strains and suggesting pathogen adaptation. In the Netherlands, the resurgence of pertussis is associated with the rise of B. pertussis strains with an altered promoter region for pertussis toxin (ptxP3). Results We used Multi-Locus Sequence Typing (MLST), Multiple-Locus Variable Number of Tandem Repeat Analysis (MLVA) and microarray-based comparative genomic hybridization (CGH) to characterize the ptxP3 strains associated with the Dutch epidemic. For CGH analysis, we developed an oligonucleotide (70-mers) microarray consisting of 3,581 oligonucleotides representing 94% of the gene repertoire of the B. pertussis strain Tohama I. Nine different MLST profiles and 38 different MLVA types were found in the period 1993 to 2004. Forty-three Dutch clinical isolates were analyzed with CGH, 98 genes were found to be absent in at least one of the B. pertussis strains tested, these genes were clustered in 8 distinct regions of difference. Conclusion The presented MLST, MLVA and CGH-analysis identified distinctive characteristics of ptxP3 B. pertussis strains -the most prominent of which was a genomic deletion removing about 23,000 bp. We propose a model for the emergence of ptxP3 strains.