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B J Luft

Publications and source records attributed to B J Luft.

At least 19 recordsLinked to original sources
PubMed2001

Dose-escalation, phase I/II study of azithromycin and pyrimethamine for the treatment of toxoplasmic encephalitis in AIDS.

OBJECTIVE: To assess the safety, tolerance and activity of increasing doses of azithromycin in combination with pyrimethamine for the treatment of toxoplasmic encephalitis (TE) in patients with AIDS. DESIGN: A phase I/II dose-escalation study of oral azithromycin in combination with pyrimethamine. SETTING: Eight clinical sites in the United States. PATIENTS: Forty-two adult HIV-infected patients with confirmed or presumed acute TE. METHODS: Patients were enrolled into three successive cohorts receiving azithromycin 900, 1200 and 1500 mg a day with pyrimethamine as induction therapy. The induction period was 6 weeks followed by 24 weeks of maintenance therapy. MAIN OUTCOME MEASURES: Patient response was evaluated clinically and radiologically. RESULTS: Of the 30 evaluable patients, 20 (67%) responded to therapy during the induction period. Ten experienced disease progression. Of the 15 patients who received maintenance therapy, seven (47%) relapsed. Six patients discontinued treatment during the induction period as a result of reversible toxicities. Treatment-terminating adverse events occurred most frequently among the patients receiving the 1500 mg dose. CONCLUSION: The combination of azithromycin (900-1200 mg a day) and pyrimethamine may be useful as an alternative therapy for TE among patients intolerant of sulfonamides and clindamycin, but maintenance therapy with this combination was associated with a high relapse rate. The combination was safe, but low-grade adverse events were common.

AIDS-Related Opportunistic Infections↗
PubMed2001

Crystal structure of outer surface protein C (OspC) from the Lyme disease spirochete, Borrelia burgdorferi.

Outer surface protein C (OspC) is a major antigen on the surface of the Lyme disease spirochete, Borrelia burgdorferi, when it is being transmitted to humans. Crystal structures of OspC have been determined for strains HB19 and B31 to 1.8 and 2.5 A resolution, respectively. The three-dimensional structure is predominantly helical. This is in contrast to the structure of OspA, a major surface protein mainly present when spirochetes are residing in the midgut of unfed ticks, which is mostly beta-sheet. The surface of OspC that would project away from the spirochete's membrane has a region of strong negative electrostatic potential which may be involved in binding to positively charged host ligands. This feature is present only on OspCs from strains known to cause invasive human disease.

Amino Acid Sequence↗
PubMed2001

Immunoblot profile as predictor of toxoplasmic encephalitis in patients infected with human immunodeficiency virus.

In order to define more accurately human immunodeficiency virus-infected patients at risk of developing toxoplasmic encephalitis (TE), we assessed the prognostic significance of the anti-Toxoplasma gondii immunoglobulin G (IgG) immunoblot profile, in addition to AIDS stage, a CD4(+) cell count <50/mm(3), and an antibody titer > or =150 IU/ml, in patients with CD4 cell counts <200/mm(3) and seropositive for T. gondii. Baseline serum samples from 152 patients included in the placebo arm of the ANRS 005-ACTG 154 trial (pyrimethamine versus placebo) were used. The IgG immunoblot profile was determined using a Toxoplasma lysate and read using the Kodak Digital Science 1D image analysis software. Mean follow-up was 15.1 months, and the 1-year incidence of TE was 15.9%. The cumulative probability of TE varied according to the type and number of anti-T. gondii IgG bands and reached 65% at 12 months for patients with IgG bands of 25 and 22 kDa. In a Cox model adjusted for age, gender, Centers for Disease Control and Prevention (CDC) clinical stage, and CD4 and CD8 cell counts, the incidence of TE was higher when the IgG 22-kDa band (hazard ratio [HR] = 5.4; P < 0.001), the IgG 25-kDa band (HR = 4.7; P < 0.001), or the IgG 69-kDa band (HR = 3.4; P < 0.001) was present and was higher for patients at CDC stage C (HR = 4.9; P < 0.001). T. gondii antibody titer and CD4 cell count were not predictive of TE. Thus, detection of IgG bands of 25, 22, and/or 69 kDa may be helpful for deciding when primary prophylaxis for TE should be started or discontinued, especially in the era of highly active antiretroviral therapy.

AIDS-Related Opportunistic Infections↗
PubMed2000

Structural identification of a key protective B-cell epitope in Lyme disease antigen OspA.

Outer surface protein A (OspA) is a major lipoprotein of the Borrelia burgdorferi spirochete, the causative agent of Lyme disease. Vaccination with OspA generates an immune response that can prevent bacterial transmission to a mammalian host during the attachment of an infected tick. However, the protective capacity of immune sera cannot be predicted by measuring total anti-OspA antibody. The murine monoclonal antibody LA-2 defines an important protective B-cell epitope of OspA against which protective sera have strong levels of reactivity. We have now mapped the LA-2 epitope of OspA using both NMR chemical-shift perturbation measurements in solution and X-ray crystal structure determination. LA-2 recognizes the three surface-exposed loops of the C-terminal domain of OspA that are on the tip of the elongated molecule most distant from the lipid-modified N terminus. The structure suggests that the natural variation at OspA sequence position 208 in the first loop is a major limiting factor for antibody cross-reactivity between different Lyme disease-causing Borrelia strains. The unusual Fab-dominated lattice of the crystal also permits a rare view of antigen flexibility within an antigen:antibody complex. These results provide a rationale for improvements in OspA-based vaccines and suggest possible designs for more direct tests of antibody protective levels in vaccinated individuals.

Amino Acid Sequence↗
PubMed2000

Recombinant chimeric Borrelia proteins for diagnosis of Lyme disease.

Current serologic Lyme disease tests use whole borrelia cells as the source of antigen. These assays are difficult to standardize and to optimize for sensitivity and specificity. To help solve these problems, we constructed a library of recombinant chimeric proteins composed of portions of key antigens of Borrelia burgdorferi. These proteins were then used to develop an enzyme-linked immunosorbent assay. We compared our assay with the most sensitive of three whole-cell borrelia assays. We found that the recombinant assay could detect antibodies significantly better from early Lyme disease sera (P<0.05), and had the same sensitivity for late Lyme disease sera, as the most sensitive whole-cell borrelia assay. On potentially cross-reactive sera, the recombinant assay was more specific, but not significantly so, than the best whole-cell borrelia assay. Optimization of the recombinant assay offers the potential for a significant improvement in both sensitivity and specificity.

Antibodies, Bacterial↗
PubMed1999

Infection with multiple strains of Borrelia burgdorferi sensu stricto in patients with Lyme disease.

OBJECTIVE: To assess human skin biopsy specimens from erythema migrans lesions for the presence of infection with multiple strains of the Lyme disease spirochete, Borrelia burgdorferi. DESIGN: Skin biopsy specimens were obtained prospectively from patients with erythema migrans. To determine allelic differences and strain identification of B burgdorferi, the biopsy specimens were analyzed by cold single-strand conformation polymorphism of an amplified fragment of the outer surface protein C (ospC) gene. Further single-strand conformation polymorphism patterns of amplified ospC genes from culture isolates were compared with polymerase chain reaction products obtained directly from erythema migrans biopsy specimens. SETTING: A private dermatology office and a university medical center outpatient department. PATIENTS: Sixteen patients presenting with erythema migrans. RESULTS: Two of the 16 patients in this cohort were infected with 2 B burgdorferi sensu stricto strains, as evidenced by 2 ospC alleles in their skin biopsy results. CONCLUSION: This is the first documented description of the existence of more than a single strain of B burgdorferi sensu stricto in a human specimen.

Adult↗
PubMed1999

Genetic diversity of ospC in a local population of Borrelia burgdorferi sensu stricto.

The outer surface protein, OspC, is highly variable in Borrelia burgdorferi sensu stricto, the agent of Lyme disease. We have shown that even within a single population OspC is highly variable. The variation of ospA and ospC in the 40 infected deer ticks collected from a single site on Shelter Island, New York, was determined using PCR-SSCP. There is very strong apparent linkage disequilibrium between ospA and ospC alleles, even though they are located on separate plasmids. Thirteen discernible SSCP mobility classes for ospC were identified and the DNA sequence for each was determined. These sequences, combined with 40 GenBank sequences, allow us to define 19 major ospC groups. Sequences within a major ospC group are, on average, <1% different from each other, while sequences between major ospC groups are, on average, approximately 20% different. The tick sample contains 11 major ospC groups, GenBank contains 16 groups, with 8 groups found in both samples. Thus, the ospC variation within a local population is almost as great as the variation of a similar-sized sample of the entire species. The Ewens-Watterson-Slatkin test of allele frequency showed significant deviation from the neutral expectation, indicating balancing selection for these major ospC groups. The variation represented by major ospC groups needs to be considered if the OspC protein is to be used as a serodiagnostic antigen or a vaccine.

Alleles↗
PubMed1999

Four clones of Borrelia burgdorferi sensu stricto cause invasive infection in humans.

Lyme disease begins at the site of a tick bite, producing a primary infection with spread of the organism to secondary sites occurring early in the course of infection. A major outer surface protein expressed by the spirochete early in infection is outer surface protein C (OspC). In Borrelia burgdorferi sensu stricto, OspC is highly variable. Based on sequence divergence, alleles of ospC can be divided into 21 major groups. To assess whether strain differences defined by ospC group are linked to invasiveness and pathogenicity, we compared the frequency distributions of major ospC groups from ticks, from the primary erythema migrans skin lesion, and from secondary sites, principally from blood and spinal fluid. The frequency distribution of ospC groups from ticks is significantly different from that from primary sites, which in turn is significantly different from that from secondary sites. The major groups A, B, I, and K had higher frequencies in the primary sites than in ticks and were the only groups found in secondary sites. We define three categories of major ospC groups: one that is common in ticks but very rarely if ever causes human disease, a second that causes only local infection at the tick bite site, and a third that causes systemic disease. The finding that all systemic B. burgdorferi sensu stricto infections are associated with four ospC groups has importance in the diagnosis, treatment, and prevention of Lyme disease.

Antigens, Bacterial↗
PubMed1998

NMR identification of epitopes of Lyme disease antigen OspA to monoclonal antibodies.

Outer surface protein A (OspA) from the Lyme disease spirochete Borrelia burgdorferi has been a focus of vaccine development. We have identified epitopes of OspA to two monoclonal antibodies (mAbs) by comparing NMR chemical shifts of free OspA and those in Fab complexes. Deuteration of non-labile protons in OspA extended the size limit of this technique so that it was applicable to the 78 kDa complexes of OspA and the Fab fragment. The epitope identified by NMR to an mAb, 184.1, agrees well with that previously defined by the crystal structure of the same complex, indicating the ability of the NMR method to accurately map an epitope in a large protein complex. The technique mapped the epitope to mAb 336, a mAb of clinical interest, to a region centered at the C-terminal alpha-helix. The results provides a basis for rational design of OspA-based Lyme disease vaccines.

Amino Acid Sequence↗
PubMed1997

Simultaneous expression of Borrelia OspA and OspC and IgM response in cerebrospinal fluid in early neurologic Lyme disease.

Lyme disease is the major tick-borne disease, caused by Borrelia burgdorferi (Bb). Neurological involvement is common in all stages. In vivo expression of Bb antigens (Ags) and the immune response to them has not been well investigated in the cerebrospinal fluid (CSF). Upregulation of outer surface protein (Osp) C and concomitant downregulation of OspA before tick inoculation of the spirochete has been reported in skin and blood in animals. CSF OspA Ag in early disease suggests otherwise in CSF. Early Ag expression and IgM response in human CSF was investigated here. Paired CSF and serum was collected from 16 early, predominantly erythema migrans Lyme disease patients with neurologic problems, 13 late Lyme disease patients, and 19 other neurologic disease (OND) controls. Samples were examined for IgM reactivity to recombinant Bb-specific Osps using ELISA and immunoblot. Of 12 early Lyme disease patients with neurologic involvement with both CSF and serum IgM against OspC, 7 (58%) had IgM to OspA (n = 5) or OspB (n = 2) that was restricted to the CSF, not serum. Overall, 12 of 16 (75%) of these early Lyme disease patients with neurologic involvement had CSF and serum IgM against OspC. Only 3 of 13 (23%) late Lyme disease patients and none of 19 OND controls had CSF IgM directed against OspC. In conclusion, in CSF, OspC and OspA can be coexpressed, and IgM response to them occurs in early Lyme disease patients with neurologic involvement. This biologic finding may also provide a discriminating marker for CNS infection in Lyme disease.

Adolescent↗
PubMed1997

Ceftriaxone compared with doxycycline for the treatment of acute disseminated Lyme disease.

BACKGROUND: Localized Lyme disease, manifested by erythema migrans, is usually treated with oral doxycycline or amoxicillin. Whether acute disseminated Borrelia burgdorferi infection should be treated differently from localized infection is unknown. METHODS: We conducted a prospective, open-label, randomized, multicenter study comparing parenteral ceftriaxone (2 g once daily for 14 days) with oral doxycycline (100 mg twice daily for 21 days) in patients with acute disseminated B. burgdorferi infection but without meningitis. The erythema migrans skin lesion was required for study entry, and disseminated disease had to be indicated by either multiple erythema migrans lesions or objective evidence of organ involvement. RESULTS: Of 140 patients enrolled, 133 had multiple erythema migrans lesions. Both treatments were highly effective. Rates of clinical cure at the last evaluation were similar among the patients treated with ceftriaxone (85 percent) and those treated with doxycycline (88 percent); treatment was considered to have failed in only one patient in each group. Among patients whose infections were cured, 18 of 67 patients in the ceftriaxone group (27 percent) reported one or more residual symptoms at the last follow-up visit, as did 10 of 71 patients in the doxycycline group (14 percent, P > or = 0.05). Mild arthralgia was the most common persistent symptom. Both regimens were well tolerated; only four patients (6 percent) in each group withdrew because of adverse events. CONCLUSIONS: In patients with acute disseminated Lyme disease but without meningitis, oral doxycycline and parenterally administered ceftriaxone were equally effective in preventing the late manifestations of disease.

Acute Disease↗
PubMed1997

Crystal structure of Lyme disease antigen outer surface protein A complexed with an Fab.

OspA (outer surface protein A) is an abundant immunogenic lipoprotein of the Lyme disease spirochete Borrelia burgdorferi. The crystal structure of a soluble recombinant form of OspA was solved in a complex with the Fab fragment of mouse monoclonal antibody 184.1 and refined to a resolution of 1.9 A. OspA has a repetitive antiparallel beta topology with an unusual nonglobular region of "freestanding" sheet connecting globular N- and C-terminal domains. Arrays of residues with alternating charges are a predominant feature of the folding pattern in the nonglobular region. The 184.1 epitope overlaps with a well conserved surface in the N-terminal domain, and a hydrophobic cavity buried in a positively charged cleft in the C-terminal domain is a potential binding site for an unknown ligand. An exposed variable region on the C-terminal domain of OspA is predicted to be an important factor in the worldwide effectiveness of OspA-based vaccines.

Amino Acid Sequence↗
PubMed1997

Survival after AIDS-defining events in patients with < 200 lymphocytes CD4+ x 10(6)/L who are toxoplasmosis antibody positive. ANRS 005/ACTG 154 Trial Group.

The objective of this study was to assess whether patients with CD4+ cell counts <200 x 10(6)/L have a decreased survival after the occurrence of any AIDS-defining event; 187 patients from the placebo arm of a clinical trial of toxoplasmosis prophylaxis (ANRS005-ACTG154) were included. For this analysis, patients were HIV infected without any AIDS-defining event, had a CD4+ lymphocyte count < 200 x 10(6)/L, had a positive serology for Toxoplasma gondii, and had no severe liver, renal, or hematologic abnormalities. We used proportional hazards regression to study the relationships between baseline variables. AIDS-defining events as time-dependent variables, and survival. The risk of dying was increased by 1.9 for a 10-year increase in age and by 1.3 when CD4+ decreased by 50 x 10(6)/L; after the occurrence of a pneumocystosis, a cytomegalovirus infection, or a toxoplasmosis, the risk of dying was multiplied, respectively, by 10.9 (3.0-40.2), 10.0 (2.8-35.4), and 10.0 (4.5-22.2). None of the other AIDS-defining events was associated with an increased risk of dying, but the power to detect such an association was limited. We conclude that the occurrence of pneumocystosis, cytomegalovirus infection, or toxoplasmosis; age; and CD4+ cell count are important determinants of survival for HIV1-infected patients with CD4+ counts < 200 x 10(6)/L who are toxoplasmosis antibody positive.

AIDS-Related Opportunistic Infections↗
PubMed1997

Increased risk of toxoplasmic encephalitis in human immunodeficiency virus-infected patients with pyrimethamine-related rash. ANRS 005-ACTG 154 Trial Group. Agence Nationale de Recherche sur le SIDA (ANRS-INSERM) and the NIAID-AIDS Clinical Trials Group.

Although drug-induced rash is frequent in human immunodeficiency virus (HIV)-infected patients, rash due to pyrimethamine has not been described previously. In a randomized, double-blind, placebo-controlled study of pyrimethamine as primary prophylaxis for toxoplasmic encephalitis, the incidence of rash (per hundred patient-years) was 8.1 in the pyrimethamine group versus 1.5 in the placebo group (P < .0002). The 1-year incidence of toxoplasmic encephalitis after occurrence of rash was 37%, as compared with 9.6% in the pyrimethamine group without rash, with a 3.7 times higher risk for patients with pyrimethamine-induced rash (P = .001); the incidence was 13% in the placebo group. At the time of toxoplasmic encephalitis, pyrimethamine was successfully readministered to 80% of patients who discontinued it because of rash. Thus, pyrimethamine, when used for prophylaxis, does induce rash in HIV-infected patients. These patients are at higher risk for toxoplasmic encephalitis and should be carefully monitored for it.

AIDS-Related Opportunistic Infections↗
PubMed1997

A population genetic study of Borrelia burgdorferi sensu stricto from eastern Long Island, New York, suggested frequency-dependent selection, gene flow and host adaptation.

Eastern Long Island, New York, is one of the major foci of Lyme disease in the United States. As in almost all other parts of North America, Lyme disease in this region is caused by a single genomic species of spirochete, Borrelia burgdorferi sensu stricto. For three consecutive years, natural populations of Lyme Borrelia in this region were sampled and studied for gene flow among different locations, changes in population structure over time, and selective forces. The genetic diversity of Borrelia populations was measured at the outer surface protein A (ospA) locus using Cold Single-Stranded Conformation Polymorphism (Cold SSCP) analysis. The Borrelia populations were found to be highly polymorphic within any of thirteen local populations. Ewens-Watterson tests of neutrality revealed that the high level of genetic diversity within local Borrelia populations is maintained by balancing selection. Frequency-dependent selection for the different strains distinguished by the ospA alleles is likely the mechanism of the balancing selection. Allele frequency distributions of Borrelia populations were homogeneous across the region in any particular year, although different infection rates of local tick (Ixodes scapularis) populations suggested that the Borrelia populations were at least partially isolated. Since the allele frequency distribution changed over time, while remaining homogeneous over space, the nearly uniform allele frequency distribution across the region cannot be explained by recent geographic expansion from a single population. This uniform distribution across the region thus may be maintained by selection, or by a significant amount of migration or both. The genetic structure of B. burgdorferi sensu stricto also differed between spirochetes infecting nymphal ticks and those infecting adult ticks. Since larval and nymphal ticks have distinctly different host feeding preferences, host adaptation of spirochete populations is implied. This distinction and an animal study using chipmunks suggest that ticks infected by Borrelia as larvae may have high mortality in the wild. This study represents a genetic analysis of local populations of a bacterial species.

Alleles↗