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Biomedical subjects

Nelson L Michael

Publications and source records attributed to Nelson L Michael.

At least 19 recordsLinked to original sources
PubMed2006

Sensitivity of the Multispot HIV-1/HIV-2 rapid test using samples from human immunodeficiency virus type 1-positive individuals with various levels of exposure to highly active antiretroviral therapy.

The Multispot HIV-1/HIV-2 rapid test detects human immunodeficiency virus type 1 (HIV-1) gp41 antibodies, which can wane over time in some HIV-1-infected populations, resulting in false-negative screening results. Multispot sensitivity was 100% using 248 sera from one such population, and it correctly identified serostatus in individuals who previously tested false negative with rapid testing.

Adult↗
PubMed2005

Use of stored serum from Uganda for development and evaluation of a human immunodeficiency virus type 1 testing algorithm involving multiple rapid immunoassays.

We report the development and evaluation of a human immunodeficiency virus type 1 testing algorithm consisting of three rapid antibody detection tests. Stored serum samples from Uganda were utilized with a final algorithm sensitivity of 100% and a specificity of 98.9% (95% confidence interval, 98.6% to 99.3%).

AIDS Serodiagnosis↗
PubMed2005

PCR amplification, cloning, and construction of HIV-1 infectious molecular clones from virtually full-length HIV-1 genomes.

The development of mixtures of highly processive and high-fidelity thermostable DNA polymerases has enabled the routine recovery of DNA sequences in excess of 25 kb generated by polymerase chain reaction. This powerful tool has been instrumental in the ability to recover virtually full-length HIV-1 proviral DNA as a single, contiguous fragment. Such fragments allow for the clean interpretation of the genomic organization of HIV-1 provirus, as they are not confounded by molecular mosaicism that accrues to overlapping subgenomic amplification strategies. We detail here a robust procedure to produce virtually full-length, single contiguous 9.2-kb HIV-1 amplimers whose full-length infectious potential is reconstituted upon cloning into long terminal repeat-replacement vectors. Large numbers of HIV-1 proviral clones can now be quickly generated and screened to identify the fraction of the viral quasispecies with the highest capacity for viral replication. The methods used to construct long terminal repeat-replacement vectors, amplify HIV-1 provirus, reconstitute full-length provirus, and recover viral stocks will be illustrated using a circulating recombinant form 1 (CRF01_AE, formerly known as subtype E) primary isolate.

Cloning, Molecular↗
PubMed2004

Prospective analyses of HIV-1-specific proliferative responses, recall antigen proliferative responses, and clinical outcomes in an HIV-1-seropositive cohort.

BACKGROUND: In cross-sectional studies of chronically infected individuals, lymphoproliferative responses to human immunodeficiency virus (HIV) type 1 p24 Gag antigen have previously been associated with lower virus load. It was not known whether this association would be predictive of better clinical outcome in longitudinal studies. METHODS: In blood samples from 608 HIV-seropositive individuals enrolled in a trial of glycoprotein 160 vaccine therapy over the course of 3-5 years, lymphoproliferative responses to HIV-1 antigens, tetanus toxoid (TT), and mitogens were measured and correlated with clinical outcome and other parameters of progression. Baseline lymphoproliferative responses to antigens and mitogens were used to categorize the cohort into responders or nonresponders. RESULTS: Although response to recall antigens did not correlate with clinical indices of disease progression, positive baseline lymphoproliferative responses to p24 and TT were associated with lower plasma levels of HIV-1 RNA. Persistently positive lymphoproliferative responses to the antigens also inversely correlated with repeated measurements of virus load, although the significance was lost once the measurements were adjusted for virus load and CD4(+) cell count at baseline, by use of generalized estimating equation analysis. CONCLUSIONS: These observations suggest that the effect of the association between lymphoproliferative response and virus load is established early during HIV-1 infection and does not increase over time and suggest that antigen-specific lymphoproliferative responses reflect the dynamic state of HIV-1 infection and are inversely associated with virus load.

AIDS Vaccines↗
PubMed2004

Long-term efficacy of routine access to antiretroviral-resistance testing in HIV type 1-infected patients: results of the clinical efficacy of resistance testing trial.

The long-term efficacy of making resistance testing routinely available to clinicians has not been established. We conducted a clinical trial at 6 US military hospitals in which volunteers infected with human immunodeficiency virus type-1 were randomized to have routine access to phenotype resistance testing (PT arm), access to genotype resistance testing (GT arm), or no access to either test (VB arm). The primary outcome measure was time to persistent treatment failure despite change(s) in antiretroviral therapy (ART) regimen. Overall, routine access to resistance testing did not significantly increase the time to end point. Time to end point was significantly prolonged in the PT arm for subjects with a history of treatment with > or =4 different ART regimens or a history of treatment with nonnucleoside reverse-transcriptase inhibitors before the study, compared with that in the VB arm. These results suggest that routine access to resistance testing can improve long-term virologic outcomes in HIV-infected patients who are treatment experienced but may not impact outcome in patients who are naive to or have had limited experience with ART.

Adult↗
PubMed2004

Use of rapid and conventional testing technologies for human immunodeficiency virus type 1 serologic screening in a rural Kenyan reference laboratory.

We report a prospective comparison of human immunodeficiency virus type 1 testing by enzyme immunoassay and Western blot with four rapid tests of 486 subjects performed in rural Kenya. Rapid test sensitivity was 100%. Specificity ranged from 99.1 to 100%. Combined use of two Food and Drug Administration-approved rapid tests yielded a single false-positive result.

Acquired Immunodeficiency Syndrome↗
PubMed2003

Effects of CCR5-Delta32 and CCR2-64I alleles on HIV-1 disease progression: the protection varies with duration of infection.

OBJECTIVE: To examine temporal variation in the effects of CCR5-Delta32 and CCR2-64I chemokine receptor gene polymorphisms on HIV-1 disease progression. DESIGN: Pooled analysis of individual patient data from 10 cohorts of HIV-1 seroconverters from the United States, Europe, and Australia. METHODS: We studied HIV-1 seroconverters of European (n = 1635) or African (n = 215) ancestry who had been genotyped for CCR5-Delta32 and CCR2-64I. We used Cox proportional hazards models with time-varying coefficients to determine whether the genetic protection against AIDS (1987 case definition) and death varied with time since seroconversion. RESULTS: Protection against AIDS conferred by CCR5-Delta32 held constant at a 31% (RH 0.69, 95% CI 0.54, 0.88) reduction in risk over the course of HIV-1 infection, whereas protection against death held constant at a 39% reduction in risk (RH 0.61, 95% CI 0.45, 0.88). When the period from AIDS to death was isolated, the survival benefit of CCR5-Delta32 diminished 2 years after AIDS. Protection against AIDS conferred by CCR2-64I was greatest early in the disease course. Compared with individuals without CCR5-Delta32 or CCR2-64I, individuals with one or two copies of CCR2-64I had a 58% lower risk of AIDS during the first 4 years after seroconversion (RH 0.42, 95% CI 0.23, 0.76), a 19% lower risk during the subsequent 4 years (RH 0.81, 95% CI 0.59, 1.12), and no significant protection thereafter. CONCLUSION: The protection against AIDS provided by CCR5-Delta32 is continuous during the course of infection. In contrast, the protection provided by CCR2-64I is greatest early in the course of infection.

Acquired Immunodeficiency Syndrome↗
PubMed2003

Performance characteristics of human immunodeficiency virus type 1 (HIV-1) genotyping systems in sequence-based analysis of subtypes other than HIV-1 subtype B.

Given the diversity of human immunodeficiency virus type 1 (HIV-1) subtypes and the emergence of subtypes other than HIV-1 subtype B in the United States, genotypic assays must be capable of delivering sequence data on diverse HIV-1 subtypes. We evaluated the performance of Visible Genetics TRUGENE HIV-1 genotyping kit and Applied Biosystems ViroSeq HIV-1 genotyping system on a panel of 34 well-characterized HIV-1 viral stocks (subtypes A through H). Both assays perform well on diverse HIV-1 subtypes despite being designed for HIV-1 subtype B. The TRUGENE assay produced sequence data for 31 isolates but not for one C and two G isolates. The TRUGENE assay using prototype 1.5 RT-PCR primers and the ViroSeq assay were both successful for all variants tested, although five isolates lacked double-strand sequence coverage in the ViroSeq assay. The availability of standardized HIV-1 genotyping kits that perform reliably with all HIV subtypes will facilitate broad implementation of HIV-1 resistance testing.

Genotype↗
PubMed2003

Performance of the OraQuick rapid antibody test for diagnosis of human immunodeficiency virus type 1 infection in patients with various levels of exposure to highly active antiretroviral therapy.

With oral mucosal transudate and serum samples from 101 human immunodeficiency virus type 1 (HIV-1)-infected subjects and 100 HIV-1-negative volunteers, the OraQuick HIV-1 test demonstrated 100% specificity and 96% sensitivity. Four false-negative subjects, who were characterized by early initiation of effective antiretroviral therapy, demonstrated waning serum anti-gp41 titers and Western blot band intensities.

Adult↗
PubMed2002

Antiviral activity of the neutralizing antibodies 2F5 and 2G12 in asymptomatic HIV-1-infected humans: a phase I evaluation.

BACKGROUND: The human monoclonal antibodies (MAbs) 2F5 and 2G12 were identified to be two of the most potent neutralizing antibodies against HIV-1. In a first human study they have been shown to be safe after repeated intravenous infusions to asymptomatic HIV-1-infected individuals. However, the antiviral effects of antibody treatment have not been fully analyzed in this first clinical trial. METHODS: The aim of the present study was to gain a preliminary insight into the antiviral effects of 2F5 and 2G12 in humans. For this purpose, plasma samples obtained from the previous phase I study were studied for RNA copy numbers by reverse transcriptase-polymerase chain reaction. As a measure for activation of complement levels of the major complement factor C3 were measured by enzyme-linked immunosorbent assay. Flow cytometry was used to study T-lymphocyte counts and the amount of infected peripheral blood mononuclear cells (PBMC) was determined by co-culture with uninfected donor PBMC. Virus escape from antibody neutralization was determined in vitro in a PBMC neutralization assay. RESULTS: Transient reduction in viral loads was observed in five of seven patients. Vigorous complement activation was observed directly after HIV-specific antibody infusions. The number of infective peripheral blood mononuclear cells was reduced in some patients whereas CD4+ T-lymphocyte counts and CD4+/CD8+ ratios were transiently increased in all patients. Virus escape occurred only against 2G12. CONCLUSIONS: Analysis of disease progression markers indicate that antibody therapy may have antiviral effects. These findings suggest that neutralizing antibodies should be further evaluated as an alternative therapeutic approach in HIV-1 disease.

Adult↗
PubMed2002

Demonstration of de novo HIV type 1 production by detection of multiply spliced and unspliced HIV type 1 RNA in paraffin-embedded tonsils.

HIV-1 infection of tonsils takes place when virus spreads systemically, and may occur when tonsillar tissue serves as the initial portal of HIV-1 entry. The HIV replication cycle includes the production of regulatory and accessory gene mRNAs, produced by splicing of genomic mRNA, that are hallmarks of de novo virus production. We sought to demonstrate, for the first time, the presence of multiply spliced viral RNA transcripts in archival tissue as a marker for active virus replication. Further, amplified cDNA sequences from unspliced pol gene mRNA were used to define the genetic subtype of HIV-1 within these tissues. RNA was extracted from surgical pathological, formalin-fixed, paraffin-embedded specimens, and RT-PCR was performed with primers for unspliced and multiply spliced HIV-1 transcripts. Amplification products were analyzed by agarose gel electrophoresis and their specificity was confirmed by sequencing and Southern blot hybridization. Unspliced HIV-1 pol transcripts yielded cDNA amplicons of 184 base pairs (bp) that were cloned and sequenced. Phylogenetic analysis revealed these sequences to be of HIV-1 subtype B. Multiply spliced transcripts specific for the tat/rev (173 bp), tat (268 bp), and tat/rev/nef (146 bp) regulatory gene mRNAs could be demonstrated in all cases. These results support the demonstration of active replication of HIV-1 in archival tonsillar tissues previously shown by p24 antigen staining. They also show the feasibility of performing molecular epidemiologic studies on HIV-1 cDNA sequences from archived pathologic specimens.

Base Sequence↗
PubMed2002

Comparative analysis of HIV-1 viral load assays on subtype quantification: Bayer Versant HIV-1 RNA 3.0 versus Roche Amplicor HIV-1 Monitor version 1.5.

Quantification of HIV-1 subtypes is essential for appropriate clinical management. Whereas viral load assays were initially developed to accurately quantify subtype B, the recent worldwide spread of non-B subtypes and the introduction of treatment programs in regions with non-B subtypes have prompted adaptations of these assays. The Bayer Versant HIV-1 RNA 3.0 Assay (branched DNA [bDNA] 3.0) and the Roche Amplicor HIV-1 Monitor version 1.5 (Amplicor 1.5) assays are reported to quantify all subtypes in group M; however, evaluation of performance characteristics remains limited. In this study, we evaluated the accuracy and reliability of bDNA 3.0 and Amplicor 1.5 on multiple serially diluted viral isolates from HIV-1 group M, subtypes A through F. Testing was conducted on both assay systems in two independent laboratories. Comparative pansubtype quantification from regression analysis showed that quantification by bDNA 3.0 was approximately 0.3 log-fold lower than that by Amplicor 1.5. Comparative pansubtype accuracy analysis showed data points more closely distributed about their respective regression lines and thus showing greater reliability by bDNA 3.0 than by Amplicor 1.5.

Branched DNA Signal Amplification Assay↗
PubMed2002

HIV-1 infection in individuals with the CCR5-Delta32/Delta32 genotype: acquisition of syncytium-inducing virus at seroconversion.

Homozygosity for the 32 base-pair deletion (Delta32/Delta32) in the CCR5 coreceptor gene is associated with incomplete HIV-1 resistance. Six HIV-1-infected Delta32/Delta32 patients have been reported. We report 2 additional Delta32/Delta32-infected individuals, among 106 seroconverters in a vaccine preparedness study. Like the previous 6, these individuals experienced rapid CD4 decline. However, taken together, the 8 patients have neither uniformly high virus load nor rapid progression to AIDS. We obtained five virus isolates from 1 patient at 5, 6, 7, 10, and 12 months after the estimated time of infection. The earliest isolate exhibits the syncytium-inducing (SI) phenotype and exclusive use of the CXCR4 coreceptor, suggesting acquisition of HIV-1 through this coreceptor. Of the remaining 104 seroconverters, 8 were CCR5-Delta32/+ and 96 were CCR5-+/+. Three CCR5-+/+ seroconverters who showed the uncommon pattern of early SI virus and rapid CD4 decline had uniformly high viral load and more heterogeneous coreceptor usage. These results further support the conclusion that Delta32-mediated resistance is incomplete and is associated with acquisition of exclusively-X4 variants of HIV-1. The pathogenic potential of these viruses may be different from late-stage X4 virus or early X4 virus acquired by individuals with other CCR5 genotypes.

Base Pairing↗
PubMed2002

Impact of viral infection on the gene expression profiles of proliferating normal human peripheral blood mononuclear cells infected with HIV type 1 RF.

Exploiting the power of high-density gene arrays, the simultaneous expression analysis of 5600 cellular genes was executed on proliferating peripheral blood mononuclear cells (PBMCs) from three normal human donors that were infected in vitro with the T cell tropic laboratory strain of HIV-1, RF. Profiles of expressed genes were assessed at 1, 12, 24, 48, and 72 hr postinfection and compared with those of matched uninfected PBMCs. Viral infection resulted in an overall increase in the number of genes expressed with peaks of expression at 1, 12, and 48 hr postinfection. Functional clustering of genes whose expression level in infected PBMCs varied by 2-fold or greater from levels in the controls indicated that cellular activation markers, proteins associated with immune cell function and with transcription and translation, exhibited increased expression subsequent to viral infection. Gene families exhibiting a decline in gene expression were confined to the 72 hr time point and included genes associated with catabolism and a subset of genes involved with cell signaling and synthetic pathways. Self-organizing map (SOM) cluster analysis identified temporal patterns of coordinated gene expression in infected PBMCs including genes associated with the immune response, the cytoskeleton, and ribosomal subunit structural proteins required for protein synthesis.

Cell Division↗
PubMed2002

A phase I trial with two human monoclonal antibodies (hMAb 2F5, 2G12) against HIV-1.

OBJECTIVE: To study the safety, immunogenicity and pharmacokinetics of two intravenously administered human monoclonal antibodies (hMAb 2F5, 2G12) against HIV-1 in humans. DESIGN: Open label clinical phase I trial. SETTING: Primary institutional care. PATIENTS: Seven HIV-1-infected healthy volunteers with > or = 500 x 10(6)CD4 cells/l and < or = 10,000 HIV-1 RNA copies/ml, not treated with highly active antiretroviral therapy (HAART), entered and finished the study. INTERVENTIONS: and main outcome measures: Eight separate infusions of the hMAb were administered over a 4-week period (total dose 14 g). The safety was assessed by physical examination, blood chemistry, complete blood cell count and recording adverse events. 2F5 and 2G12 plasma levels were determined prior to and at the end of each infusion and during the follow-up period of 22 weeks. RESULTS: No clinical or laboratory abnormalities were observed throughout the study. The median distribution half-life (t(1/2 alpha)) of 2F5 and 2G12 was 1.02 (range, 0.77-1.47) days and 2.49 (range, 0.92-4.59) days, respectively. The elimination half-life (t(1/2 beta)) was calculated to be 7.94 (range, 3.46-8.31) days for 2F5 and 16.48 (range, 12.84-24.85) days for 2G12. The median plasma concentration immediately after the first infusion was 216 microg/ml (range, 158-409 microg/ml) for 2F5 and 238 microg/ml (range, 197-402 microg/ml) for 2G12. Multiple infusions resulted in maximum plasma concentrations of 374 microg/ml (range, 304-700 microg/ml) and 605 microg/ml (range, 479-897 microg/ml) for 2F5 and 2G12, respectively. CONCLUSIONS: This study showed that the hMAb 2F5 and 2G12 are safe and well tolerated by HIV-1-infected subjects.

Adult↗
PubMed2002

Transcription regulation of human chemokine receptor CCR3: evidence for a rare TATA-less promoter structure conserved between drosophila and humans.

The chemokine receptor CCR3 has a critical function in the pathogenesis of eosinophilic diseases and is an entry co-receptor for HIV-1. We describe here the genomic organization and general transcriptional control mechanism for the human gene CCR3. We identified six cDNA transcripts formed by alternative splicing of eight exons and seven introns. CCR3 contains a 37-bp core promoter domain (-3 to +34 relative to the transcription start point) lacking a TATA box but inclusive of an initiator sequence, a G at +24, and a downstream promoter element (DPE) at +28 to +33 common for Drosophila melanogaster but heretofore described for only two other human genes. Mutation of these elements significantly attenuates CCR3 transcription, as predicted by a model of RNA pol II engagement with DPE-containing Drosophila promoters. These results provide evidence for the functional conservation of a DPE-dependent, general transcription control mechanism between Drosophila and human genes.

Amino Acid Sequence↗