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Ira Schwartz

Publications and source records attributed to Ira Schwartz.

At least 19 recordsLinked to original sources
PubMed2006

Borrelia burgdorferi BBA74, a periplasmic protein associated with the outer membrane, lacks porin-like properties.

The outer membrane of Borrelia burgdorferi, the causative agent of Lyme disease, contains very few integral membrane proteins, in contrast to other gram-negative bacteria. BBA74, a Borrelia burgdorferi plasmid-encoded protein, was proposed to be an integral outer membrane protein with putative porin function and designated as a 28-kDa outer membrane-spanning porin (Oms28). In this study, the biophysical properties of BBA74 and its subcellular localization were investigated. BBA74 is posttranslationally modified by signal peptidase I cleavage to a mature 25-kDa protein. The secondary structure of BBA74 as determined by circular dichroism spectroscopy consists of at least 78% alpha-helix with little beta-sheet structure. BBA74 in intact B. burgdorferi cells was insensitive to proteinase K digestion, and indirect immunofluorescence microscopy showed that BBA74 was not exposed on the cell surface. Triton X-114 extraction of outer membrane vesicle preparations indicated that BBA74 is not an integral membrane protein. Taken together, the data indicate that BBA74 is a periplasmic, outer membrane-associated protein that lacks properties typically associated with porins.

Bacterial Outer Membrane Proteins↗
PubMed2006

Borrelia burgdorferi spirochetes that harbor only a portion of the lp28-1 plasmid elicit antibody responses detectable with the C6 test for Lyme disease.

Detection of antibody to C6, a peptide that reproduces the sequence of the sixth invariable region within the central domain of the VlsE protein of Borrelia burgdorferi, is used currently for the serologic diagnosis of Lyme disease in humans. B. burgdorferi isolates taken from infected humans can be categorized into specific genetic subtypes (designated RST1, -2, and -3) by restriction fragment length polymorphisms in the 16S to 23S rRNA spacer sequence. Many of these, usually categorized as RST2, retain only segments of the linear plasmid lp28-1, which encodes VlsE. The VlsE genetic region is retained, but altered expression of this molecule could affect diagnosis by the C6 enzyme-linked immunosorbent assay (ELISA). Serum samples from patients infected with each of the three genotypes and from mice infected with three RST2 isolates were tested with the C6 ELISA. Such isolates elicited marked C6 responses in infected mice. The sensitivity of C6 antibody detection in patients infected with RST2 spirochetes was statistically indistinguishable from detection of RST1 and RST3 infections. These findings demonstrate that diagnosis by C6 ELISA remains effective for infection with all B. burgdorferi genotypes, including those with incomplete lp28-1 plasmids.

Animals↗
PubMed2006

Dissociation between inhibition and killing by levofloxacin in human granulocytic anaplasmosis.

Human granulocytic anaplasmosis (HGA) is a potentially fatal tick-borne infection caused by Anaplasma phagocytophilum. Treatment options are limited for this entity, with doxycycline being the drug of choice. Certain fluoroquinolones such as levofloxacin are active against A. phagocytophilum in vitro. We report a hospitalized patient with HGA who improved coincident with a 13-day course of levofloxacin therapy, but clinically and microbiologically relapsed 15 days after completion of treatment. Relapse of infection after levofloxacin therapy was reproduced in a severe combined immune-deficient (SCID) mouse infection model. Quinolone therapy should not be considered curative of HGA.

Aged↗
PubMed2006

MyD88 deficiency enhances acquisition and transmission of Borrelia burgdorferi by Ixodes scapularis ticks.

Borrelia burgdorferi strains exhibit various degrees of infectivity and pathogenicity in mammals, which may be due to their relative ability to evade initial host immunity. Innate immune cells recognize B. burgdorferi by Toll-like receptors (TLRs) that use the intracellular molecule MyD88 to mediate effector functions. To determine whether impaired TLR signaling enhances Ixodes scapularis acquisition of B. burgdorferi, we fed nymphs on wild-type (WT) and MyD88-/- mice previously infected with two clinical isolates of B. burgdorferi, BL206, a high-virulence strain, and B348, an attenuated strain. Seventy-three percent of the nymphs that fed on BL206-infected WT mice and 40% of the nymphs that fed on B348-infected WT mice acquired B. burgdorferi, whereas 100% of the nymphs that fed on MyD88-/- mice became infected, irrespective of B. burgdorferi strain. Ticks that acquired infection after feeding on MyD88-/- mice harbored more spirochetes than those that fed on WT mice, as assessed by quantitative PCR for B. burgdorferi DNA. Vector transmission of BL206 and B348 was also enhanced when MyD88-/- mice were the blood meal hosts, with the mean pathogen burden at the skin inoculation site significantly higher than levels in WT mice. These results show that the absence of MyD88 facilitates passage of both low- and high-infectivity B. burgdorferi strains between the tick vector and the mammal and enhances the infectivity of a low-infectivity B. burgdorferi strain.

Adaptor Proteins, Signal Transducing↗
PubMed2006

Comparative genome hybridization reveals substantial variation among clinical isolates of Borrelia burgdorferi sensu stricto with different pathogenic properties.

Clinical and murine studies suggest that there is a differential pathogenicity of different genotypes of Borrelia burgdorferi, the spirochetal agent of Lyme disease. Comparative genome hybridization was used to explore the relationship between different genotypes. The chromosomes of all studied isolates were highly conserved (>93%) with respect to both sequence and gene order. Plasmid sequences were substantially more diverse. Plasmids lp54, cp26, and cp32 were present in all tested isolates, and their sequences and gene order were conserved. The majority of linear plasmids showed variation both in terms of presence among different isolates and in terms of sequence and gene order. The data strongly imply that all B. burgdorferi clinical isolates contain linear plasmids related to each other, but the structure of these replicons may vary substantially from isolate to isolate. These alterations include deletions and presumed rearrangements that are likely to result in unique plasmid elements in many isolates. There is a strong correlation between complete genome hybridization profiles and other typing methods, which, in turn, also correlate to differences in pathogenicity. Because there is substantially less variation in the chromosomal and circular plasmid portions of the genome, the major differences in open reading frame content and genomic diversity among isolates are linear plasmid driven.

Borrelia burgdorferi↗
PubMed2005

Association between human leukocyte antigen class II alleles and genotype of Borrelia burgdorferi in patients with early lyme disease.

BACKGROUND: On the basis of a polymerase chain reaction-restriction fragment-length polymorphism analysis of the 16S-23S ribosomal DNA intergenic spacer, clinical isolates of Borrelia burgdorferi can be classified into 3 genotypes designated as RST1, RST2, and RST3. RST1 strains are the most pathogenic, and RST3 strains are the least pathogenic. METHODS: Human leukocyte antigen (HLA) class II alleles were determined for a group of culture-positive patients with Lyme disease-associated erythema migrans and were evaluated for an association with the genotype of the infecting B. burgdorferi strain. RESULTS: The DRB1*0101 allele carriage rate was higher in patients infected with RST3 strains (9/25 [36.0%]) than in patients infected with RST1 strains (2/28 [7.1%]) or RST2 strains (7/36 [19.4%]) (P=.010). The same relationship was found for carriage of the DRB1*0101-DQB1*0501 haplotype (P=.018), because of tight linkage disequilibrium. Similar associations could not be demonstrated for any of the other DRB1 and DQB1 alleles or haplotypes that were assessed. CONCLUSION: The DRB1*0101 allele and the DRB1*0101-DQB1*0501 haplotype may be relevant to the development of infection with strains from the least invasive genotypes of B. burgdorferi.

Adult↗
PubMed2005

Microbiologic evaluation of patients from Missouri with erythema migrans.

BACKGROUND: Borrelia lonestari infects Amblyomma americanum, the tick species that is the most common cause of tick bites in southeast and south-central United States, and this spirochete has been detected in an erythema migrans (EM)-like skin rash in 1 patient. Therefore, B. lonestari is considered to be a leading candidate for the etiologic agent of EM in this region. METHODS: Skin biopsy specimens obtained from patients from the Cape Girardeau area of Missouri who had EM-like lesions were cultured in Barbour-Stoenner-Kelly medium and evaluated by polymerase chain reaction (PCR) targeting multiple genes. Serum specimens were tested by enzyme-linked immunosorbent assay for antibodies against sonicated whole-cell Borrelia burgdorferi. Results were compared with those obtained over the same period for patients from New York State who had EM. RESULTS: B. lonestari was not detected by PCR in any of 31 skin biopsy specimens collected from 30 Missouri patients. None of 19 cultures of Missouri skin samples that were suitable for evaluation were positive for B. burgdorferi, compared with 89 (63%) of 142 cultures of samples collected from New York State patients (P<.001). None of the 25 evaluable Missouri patients were seropositive for antibodies against B. burgdorferi, compared with 107 (75%) of 143 New York State patients (P<.001). CONCLUSIONS: Neither B. lonestari nor B. burgdorferi is likely to be the cause of EM-like skin lesions in patients from the Cape Girardeau area of Missouri. The etiology of this condition remains unknown.

Borrelia↗
PubMed2005

Diagnosis of lyme borreliosis.

A large amount of knowledge has been acquired since the original descriptions of Lyme borreliosis (LB) and of its causative agent, Borrelia burgdorferi sensu stricto. The complexity of the organism and the variations in the clinical manifestations of LB caused by the different B. burgdorferi sensu lato species were not then anticipated. Considerable improvement has been achieved in detection of B. burgdorferi sensu lato by culture, particularly of blood specimens during early stages of disease. Culturing plasma and increasing the volume of material cultured have accomplished this. Further improvements might be obtained if molecular methods are used for detection of growth in culture and if culture methods are automated. Unfortunately, culture is insensitive in extracutaneous manifestations of LB. PCR and culture have high sensitivity on skin samples of patients with EM whose diagnosis is based mostly on clinical recognition of the lesion. PCR on material obtained from extracutaneous sites is in general of low sensitivity, with the exception of synovial fluid. PCR on synovial fluid has shown a sensitivity of up to >90% (when using four different primer sets) in patients with untreated or partially treated Lyme arthritis, making it a helpful confirmatory test in these patients. Currently, the best use of PCR is for confirmation of the clinical diagnosis of suspected Lyme arthritis in patients who are IgG immunoblot positive. PCR should not be used as the sole laboratory modality to support a clinical diagnosis of extracutaneous LB. PCR positivity in seronegative patients suspected of having late manifestations of LB most likely represents a false-positive result. Because of difficulties in direct methods of detection, laboratory tests currently in use are mainly those detecting antibodies to B. burgdorferi sensu lato. Tests used to detect antibodies to B. burgdorferi sensu lato have evolved from the initial formats as more knowledge on the immunodominant antigens has been collected. The recommendation for two-tier testing was an attempt to standardize testing and improve specificity in the United States. First-tier assays using whole-cell sonicates of B. burgdorferi sensu lato need to be standardized in terms of antigen composition and detection threshold of specific immunoglobulin classes. The search for improved serologic tests has stimulated the development of recombinant protein antigens and the synthesis of specific peptides from immunodominant antigens. The use of these materials alone or in combination as the source of antigen in a single-tier immunoassay may someday replace the currently recommended two-tier testing strategy. Evaluation of these assays is currently being done, and there is evidence that certain of these antigens may be broadly cross-reactive with the B. burgdorferi sensu lato species causing LB in Europe.

Antibodies, Bacterial↗
PubMed2005

Comparative transcriptional profiling of Borrelia burgdorferi clinical isolates differing in capacities for hematogenous dissemination.

Borrelia burgdorferi, the etiologic agent of Lyme disease, is genetically heterogeneous. Previous studies have shown a significant association between the frequency of hematogenous dissemination in Lyme disease patients and the genotype of the infecting B. burgdorferi strain. Comparative transcriptional profiling of two representative clinical isolates with distinct genotypes (BL206 and B356) was undertaken. A total of 78 open reading frames (ORFs) had expression levels that differed significantly between the two isolates. A number of genes with potential involvement in nutrient uptake (BB0603, BBA74, BB0329, BB0330, and BBB29) have significantly higher expression levels in isolate B356. Moreover, nearly 25% of the differentially expressed genes are predicted to be localized on the cell surface, implying that these two isolates have cell surface properties that differ considerably. One of these genes, BBA74, encodes a protein of 257 amino acid residues that has been shown to possess porin activity. BBA74 transcript level was >20-fold higher in B356 than in BL206, and strain B356 contained three- to fivefold more BBA74 protein. BBA74 was disrupted by the insertion of a kanamycin resistance cassette into the coding region. The growth rates of both wild-type and mutant strains were essentially identical, and cultures reached the same final cell densities. However, the mutant strains consistently showed prolonged lags of 2 to 5 days prior to the induction of log-phase growth compared to wild-type strains. It is tempting to speculate that the absence of BBA74 interferes with the enhanced nutrient uptake that may be required for the entry of cells into log-phase growth. These studies demonstrate the value of comparative transcriptional profiling for identifying differences in the transcriptomes of B. burgdorferi clinical isolates that may provide clues to pathogenesis. The 78 ORFs identified here are a good starting point for the investigation of factors involved in the hematogenous dissemination of B. burgdorferi.

Alleles↗
PubMed2004

Impaired host defense to infection and Toll-like receptor 2-independent killing of Borrelia burgdorferi clinical isolates in TLR2-deficient C3H/HeJ mice.

To investigate the role of Toll-like receptor 2 (TLR2)-mediated signaling in host innate defense and development of Lyme disease, the pathogenicity of Borrelia burgdorferi sensu stricto clinical isolates representing two distinct genotypes (RST1 and RST3A) was assessed in TLR2(-/-) C3H/HeJ mice. All TLR2(-/-) mice infected with a B. burgdorferi RST1 isolate developed severe arthritis. The numbers of spirochetes in heart, joint and ear biopsy specimens were significantly higher in TLR2(-/-) mice than in wild-type mice similarly infected as determined by real-time quantitative polymerase chain reaction. Interestingly, despite the higher spirochete levels in heart tissues, milder carditis was observed in TLR2(-/-) than in wild-type mice infected with this RST1 isolate (P=0.02). By contrast, no positive cultures were obtained from any of the blood and tissue specimens from TLR2(-/-) mice inoculated with two RST3A clinical isolates. The data suggest that there is impaired host innate defense against infection and TLR2-independent killing of B. burgdorferi clinical isolates in TLR2-deficient C3H/HeJ mice.

Animals↗
PubMed2004

Reliability of quantitative motor unit action potential parameters.

We evaluated the test-retest reliability (reproducibility) of motor unit action potential (MUAP) parameters in multi-MUAP analysis over time. Reproducibility studies are not available for needle quantitative electromyography (QEMG) performed by the same examiner. Fourteen consecutive individuals (10 men and 4 women) had repeat QEMG at 3 hours after the first examination, and seven (5 men and 2 women) had a repeat QEMG after 4-10 days. The intraclass correlation coefficient (ICC) was 87-97% with same-day testing and 52-81% with different-day testing. Size index and firing rate were the most reproducible, suggesting use in follow-up multi-MUAP studies.

Action Potentials↗
PubMed2004

Electrical twitch-obtaining intramuscular stimulation in lower back pain: a pilot study.

OBJECTIVES: To determine if electrical twitch-obtaining intramuscular stimulation (ETOIMS) provides greater myofascial lower back pain relief than muscle stimulation or skin stimulation. DESIGN: In this single-blinded, crossover, pilot trial performed at a university-affiliated outpatient rehabilitation medicine department in Taiwan, 12 acupuncture-naive patients with lower back pain of 3-60 mos duration received one crossover treatment every 2 wks by monopolar needle electrode insertion at bilateral T10-S1 levels to: (1) paraspinal muscles, (2) overlying skin, and (3) paraspinal muscles with ETOIMS applied via the needle electrode at individual treatment sites. A total of 30 manual insertions per side per treatment were performed, with withdrawal after 2 secs. Beginning 1 wk before each trial and continuing until 2 wks after, patients completed a visual analog scale twice daily. In addition, on the day of treatment, patients received a physical examination and completed a visual analog scale both before and after treatment. RESULTS: Significant and immediate reduction in the visual analog scale levels was noted only with ETOIMS. Immediate improvement occurred in one of nine physical tests with muscle stimulation and ETOIMS only. In the 2 wks after treatment, absolute visual analog scale levels for ETOIMS were significantly lower than muscle stimulation and skin stimulation. ETOIMS resulted in a greater percentage of pain relief in the first week after treatment, although it was not statistically significant from muscle stimulation and skin stimulation. CONCLUSIONS: ETOIMS provided significantly greater immediate and sustained myofascial lower back pain relief than muscle stimulation and skin stimulation. Although a greater percentage of pain reduction occurred with ETOIMS, it was not statistically significant.

Acupuncture Therapy↗
PubMed2004

Interaction and transmission of two Borrelia burgdorferi sensu stricto strains in a tick-rodent maintenance system.

In the northeastern United States, the Lyme disease agent, Borrelia burgdorferi sensu stricto, is maintained by enzoonotic transmission, cycling between white-footed mice (Peromyscus leucopus) and black-legged ticks (Ixodes scapularis). B. burgdorferi sensu stricto is genetically variable and has been divided into three major genotypes based on 16S-23S ribosomal DNA spacer (RST) analysis. To better understand how genetic differences in B. burgdorferi sensu stricto may influence transmission dynamics in nature, we investigated the interaction between an RST1 and an RST3 strain in a laboratory system with P. leucopus mice and I. scapularis ticks. Two groups of mice were infected with either BL206 (RST1) or B348 (RST3). Two weeks later, experimental mice were challenged with the opposite strain, while control mice were challenged with the same strain as that used for the primary infection. The transmission of BL206 and B348 from infected mice was then determined by xenodiagnosis with uninfected larval ticks at weekly intervals for 42 days. Mice in both experimental groups were permissive for infection with the second strain and were able to transmit both strains to the xenodiagnostic ticks. However, the overall transmission efficiencies of BL206 and B348 were significantly different. BL206 was more efficiently transmitted than B348 to xenodiagnostic ticks. Significantly fewer double infections than expected were detected in xenodiagnostic ticks. The results suggest that some B. burgdorferi sensu stricto strains, such as BL206, may be preferentially maintained in transmission cycles between ticks and white-footed mice. Other strains, such as B348, may be more effectively maintained in different tick-vertebrate transmission cycles.

Animals↗
PubMed2004

Variations in Barbour-Stoenner-Kelly culture medium modulate infectivity and pathogenicity of Borrelia burgdorferi clinical isolates.

The effects of variations in Barbour-Stoenner-Kelly (BSK) medium on the infectivity and pathogenicity of Borrelia burgdorferi clinical isolates were assessed by retrospective and prospective studies using a murine model of Lyme borreliosis. Thirty of 35 (86%) mice infected with any of six virulent B. burgdorferi clinical isolates grown in a BSK-H medium developed clinically apparent arthritis. By contrast, arthritis was observed in only 25 of 60 (42%) mice inoculated with two of these B. burgdorferi strains grown in a different lot of BSK-H medium (P < 0.001). In a prospective study, mice inoculated with a B. burgdorferi clinical isolate grown in a BSK medium prepared in-house produced significantly greater disease than those injected with the same isolate cultured in BSK-H medium (P < 0.05). The attenuated pathogenicity is not due to the loss of plasmids during in vitro cultivation. The data suggest that variations in BSK medium have a significant impact on the infectivity and pathogenicity of B. burgdorferi clinical isolates.

Animals↗
PubMed2004

Functional properties of Borrelia burgdorferi recA.

Functions of the Borrelia burgdorferi RecA protein were investigated in Escherichia coli recA null mutants. Complementation with B. burgdorferi recA increased survival of E. coli recA mutants by 3 orders of magnitude at a UV dose of 2,000 microJ/cm(2). The viability at this UV dose was about 10% that provided by the homologous recA gene. Expression of B. burgdorferi recA resulted in survival of E. coli at levels of mitomycin C that were lethal to noncomplemented hosts. B. burgdorferi RecA was as effective as E. coli RecA in mediating homologous recombination in E. coli. Furthermore, E. coli lambda phage lysogens complemented with B. burgdorferi recA produced phage even in the absence of UV irradiation. The level of phage induction was 55-fold higher than the level in cells complemented with the homologous recA gene, suggesting that B. burgdorferi RecA may possess an enhanced coprotease activity. This study indicates that B. burgdorferi RecA mediates the same functions in E. coli as the homologous E. coli protein mediates. However, the rapid loss of viability and the absence of induction in recA expression after UV irradiation in B. burgdorferi suggest that recA is not involved in the repair of UV-induced damage in B. burgdorferi. The primary role of RecA in B. burgdorferi is likely to be a role in some aspect of recombination.

Bacteriophage lambda↗
PubMed2003

Real-time PCR for simultaneous detection and quantification of Borrelia burgdorferi in field-collected Ixodes scapularis ticks from the Northeastern United States.

The density of spirochetes in field-collected or experimentally infected ticks is estimated mainly by assays based on microscopy. In this study, a real-time quantitative PCR (qPCR) protocol targeting the Borrelia burgdorferi-specific recA gene was adapted for use with a Lightcycler for rapid detection and quantification of the Lyme disease spirochete, B. burgdorferi, in field-collected Ixodes scapularis ticks. The sensitivity of qPCR for detection of B. burgdorferi DNA in infected ticks was comparable to that of a well-established nested PCR targeting the 16S-23S rRNA spacer. Of the 498 I. scapularis ticks collected from four northeastern states (Rhode Island, Connecticut, New York, and New Jersey), 91 of 438 (20.7%) nymphal ticks and 15 of 60 (25.0%) adult ticks were positive by qPCR assay. The number of spirochetes in individual ticks varied from 25 to 197,200 with a mean of 1,964 spirochetes per nymphal tick and a mean of 5,351 spirochetes per adult tick. No significant differences were found in the mean numbers of spirochetes counted either in nymphal ticks collected at different locations in these four states (P = 0.23 by one-way analysis of variance test) or in ticks infected with the three distinct ribosomal spacer restriction fragment length polymorphism types of B. burgdorferi (P = 0.39). A high degree of spirochete aggregation among infected ticks (variance-to-mean ratio of 24,877; moment estimate of k = 0.279) was observed. From the frequency distribution data and previously published transmission studies, we estimated that a minimum of 300 organisms may be required in a host-seeking nymphal tick to be able to transmit infection to mice while feeding on mice. These data indicate that real-time qPCR is a reliable approach for simultaneous detection and quantification of B. burgdorferi infection in field-collected ticks and can be used for ecological and epidemiological surveillance of Lyme disease spirochetes.

Animals↗
PubMed2003

Profiling of temperature-induced changes in Borrelia burgdorferi gene expression by using whole genome arrays.

Borrelia burgdorferi is the etiologic agent of Lyme disease, the most prevalent arthropod-borne disease in the United States. The genome of the type strain, B31, consists of a 910,725-bp linear chromosome and 21 linear and circular plasmids comprising 610,694 bp. During its life cycle, the spirochete exists in distinctly different environments, cycling between a tick vector and a mammalian host. Temperature is one environmental factor known to affect B. burgdorferi gene expression. To identify temperature-responsive genes, genome arrays containing 1,662 putative B. burgdorferi open reading frames (ORFs) were prepared on nylon membranes and employed to assess gene expression in B. burgdorferi B31 grown at 23 and 35 degrees C. Differences in expression of more than 3.5 orders of magnitude could be readily discerned and quantitated. At least minimal expression from 91% of the arrayed ORFs could be detected. A total of 215 ORFs were differentially expressed at the two temperatures; 133 were expressed at significantly greater levels at 35 degrees C, and 82 were more significantly expressed at 23 degrees C. Of these 215 ORFs, 134 are characterized as genes of unknown function. One hundred thirty-six (63%) of the differentially expressed genes are plasmid encoded. Of particular interest is plasmid lp54 which contains 76 annotated putative genes; 31 of these exhibit temperature-regulated expression. These findings underscore the important role plasmid-encoded genes may play in adjustment of B. burgdorferi to growth under diverse environmental conditions.

Animals↗