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Russian DA, Kovacs JA. Pneumocystis carinii: a fungus resistant to antifungal therapies - mechanisms of action of antipneumocystis drugs. Drug Resist Updat 2007; 1:16-20. [PMID: 17092792 DOI: 10.1016/s1368-7646(98)80210-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Pneumocystis carinii is a pathogen that causes a potentially lethal pneumonia in patients with AIDS and other immunodeficiency states. This review discusses the mechanisms of action of four classes of antipneumocystis agents: inhibitors of ergosterol synthesis and function, 1,3-beta-glucan synthase inhibitors, antifolates and DNA binding agents. Investigations of P. carinii's biologic pathways affected by the antipneumocystis actions of each of these classes of agents has generated important insights into the organism's basic biology and supports the organism's classification as a fungus. In addition, this review discusses some recent P. carinii research and its potential impact on drug development.
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Fox SD, Lempicki RA, Hosack DA, Baseler MW, Kovacs JA, Lane HC, Veenstra TD, Issaq HJ. A comparison of microLC/electrospray ionization-MS and GC/MS for the measurement of stable isotope enrichment from a [2H2]-glucose metabolic probe in T-cell genomic DNA. Anal Chem 2004; 75:6517-22. [PMID: 14640722 DOI: 10.1021/ac030186v] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Measurement of the proliferation of lymphocytes and other high-turnover cell populations in vivo can be accomplished through the incorporation of an isotopically labeled DNA precursor into actively dividing cells and the subsequent determination of the isotope enrichment in the isolated genomic DNA from selected cell populations. Two published gas chromatography/mass spectrometry (GC/MS) methods were successfully modified by our laboratory whereby a postinjection methylation reaction, rather than silylation or acetylation, was used to form a volatile derivative of deoxyadenosine (dA). We also developed a second robust microcapillary liquid chromatography-electrospray ionization (microLC-ESI)/MS method that is faster and more sensitive than the GC/MS method and does not require sample derivatization. Following administration of [6,6-(2)H(2)]-glucose to human immunodeficiency virus-infected patients, peripheral blood was drawn; cells were obtained by lymphapheresis and fractionated. DNA was isolated from the desired cell subtypes and enzymatically hydrolyzed to the free deoxyribonucleosides. The digest was analyzed using both capillary GC/MS and microLC/ESI-MS to measure the levels of the dA and [(2)H(2)]-dA or their reaction products. Sample enrichments were calculated by comparison to standard curves prepared from dA and [(2)H(2)]-dA. The microLC/ESI-MS method required fewer cells, less sample preparation, shorter analysis times, and a single calibration curve. Overall, the microLC/ESI-MS method is superior to the GC/MS method in terms of precision and accuracy, while providing a 4-fold increase in sensitivity (from 20 pmol at 0.2% [(2)H(2)]-dA enrichment to 5 pmol at 0.1% [(2)H(2)]-dA enrichment).
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Vestereng VH, Kovacs JA. Recombinant CD40 ligand administration does not decrease intensity of Pneumocystis carinii infection in scid mice. J Eukaryot Microbiol 2002; Suppl:153S-154S. [PMID: 11906038 DOI: 10.1111/j.1550-7408.2001.tb00496.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
X-linked Hyper IgM Syndrome (HIM) is a rare congenital immunodeficiency recently demonstrated to be caused by a mutation in the gene encoding CD40 ligand. These patients are susceptible to Pneumocystis carinii pneumonia, which implies an important role for CD40L in host defense against P. carinii. In this study we undertook to investigate whether treatment of P. carinii infected scid mice with murine recombinant CD40 ligand trimer (muCD40L) for 21 days would facilitate clearance of the organisms. We found no significant difference in organism burden in treated compared to control animals. Therefore in this model treatment with muCD40L alone is ineffective in clearing P. carinii infection.
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Carney MJ, Kovacs JA, Zhang YP, Papaefthymiou GC, Spartalian K, Frankel RB, Holm RH. Comparative electronic properties of vanadium-iron-sulfur and molybdenum-iron-sulfur clusters containing isoelectronic cubane-type [VFe3S4]2+ and [MoFe3S4]3+ cores. Inorg Chem 2002. [DOI: 10.1021/ic00252a016] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Kovacs JA, Lempicki RA, Sidorov IA, Adelsberger JW, Herpin B, Metcalf JA, Sereti I, Polis MA, Davey RT, Tavel J, Falloon J, Stevens R, Lambert L, Dewar R, Schwartzentruber DJ, Anver MR, Baseler MW, Masur H, Dimitrov DS, Lane HC. Identification of dynamically distinct subpopulations of T lymphocytes that are differentially affected by HIV. J Exp Med 2001; 194:1731-41. [PMID: 11748275 PMCID: PMC2193579 DOI: 10.1084/jem.194.12.1731] [Citation(s) in RCA: 183] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
We examined the effects of human immunodeficiency virus infection on the turnover of CD4 and CD8 T lymphocytes in 17 HIV-infected patients by 30 min in vivo pulse labeling with bromodeoxyuridine (BrdU). The percentage of labeled CD4 and CD8 T lymphocytes was initially higher in lymph nodes than in blood. Labeled cells equilibrated between the two compartments within 24 h. Based on mathematical modeling of the dynamics of BrdU-labeled cells in the blood, we identified rapidly and slowly proliferating subpopulations of CD4 and CD8 T lymphocytes. The percentage, but not the decay rate, of labeled CD4 or CD8 cells in the rapidly proliferating pool correlated significantly with plasma HIV RNA levels for both CD4 (r = 0.77, P < 0.001) and CD8 (r = 0.81, P < 0.001) T cells. In six patients there was a geometric mean decrease of greater than 2 logs in HIV levels within 2 to 6 mo after the initiation of highly active antiretroviral therapy; this was associated with a significant decrease in the percentage (but not the decay rate) of labeled cells in the rapidly proliferating pool for both CD4 (P = 0.03) and CD8 (P < 0.001) T lymphocytes. Neither plasma viral levels nor therapy had an effect on the decay rate constants or the percentage of labeled cells in the slowly proliferating pool. Monocyte production was inversely related to viral load (r = -0.56, P = 0.003) and increased with therapy (P = 0.01). These findings demonstrate that HIV does not impair CD4 T cell production but does increase CD4 and CD8 lymphocyte proliferation and death by inducing entry into a rapidly proliferating subpopulation of cells.
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Kovacs JA, Gill VJ, Meshnick S, Masur H. New insights into transmission, diagnosis, and drug treatment of Pneumocystis carinii pneumonia. JAMA 2001; 286:2450-60. [PMID: 11712941 DOI: 10.1001/jama.286.19.2450] [Citation(s) in RCA: 123] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Pneumocystis carinii has been recognized as a human pathogen for nearly 50 years. We present a case of P carinii infection that typifies clinical presentation in the era of the acquired immunodeficiency syndrome epidemic. The high incidence of P carinii pneumonia in persons infected with human immunodeficiency virus (HIV) has served to focus laboratory and clinical research efforts on better understanding the biology of the organism and on improving diagnosis, treatment, and prevention of this disease. Although inability to culture P carinii has hampered research efforts, molecular and immunologic approaches have led to the recognition that the organism represents a family of fungi with a very restricted host range and have allowed characterization of clinically relevant antigens and enzymes. Molecular epidemiologic studies have identified more than 50 strains of human-derived P carinii and have suggested that recently acquired infection, as opposed to reactivation of latent infection, may account for many cases of clinical disease. Diagnosis has been improved by the development of organism-specific monoclonal antibodies and, more recently, by polymerase chain reaction using multicopy gene targets, together with induced sputum or oral wash samples. Chemotherapeutic prophylaxis is very effective in preventing P carinii pneumonia; the combination of trimethoprim-sulfamethoxazole remains the first-line agent for both therapy and prophylaxis. Prophylaxis needs to be administered only during periods of high risk; in HIV-infected patients responding to effective antiretroviral therapies, prophylaxis no longer needs to be lifelong. Molecular studies have identified mutations in the target of sulfa drugs that appear to represent emerging resistance in P carinii. Resistance to atovaquone, a second-line agent, may also be developing.
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Ma L, Imamichi H, Sukura A, Kovacs JA. Genetic divergence of the dihydrofolate reductase and dihydropteroate synthase genes in Pneumocystis carinii from 7 different host species. J Infect Dis 2001; 184:1358-62. [PMID: 11679931 DOI: 10.1086/324208] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2001] [Revised: 07/31/2001] [Indexed: 11/03/2022] Open
Abstract
To investigate the phylogenetic and therapeutic implications of the genetic divergence in the dihydrofolate reductase (DHFR) and dihydropteroate synthase (DHPS) genes among different Pneumocystis carinii strains, these 2 genes in P. carinii obtained from 7 different host species were sequenced. Pairwise comparison of the DHPS sequences demonstrated 6%-24% and 6%-30% divergence in the nucleotide and deduced amino acid sequences, respectively. The DHFR gene was even more divergent, with differences of 15%-34% and 18%-42% in the nucleotide and deduced amino acid sequences, respectively. Phylogenetic analysis of DHFR and DHPS sequences revealed that all P. carinii strains were confined within a distinct group that was closely related to ascomycete fungi and that human-derived P. carinii was most closely related to monkey-derived P. carinii. Recognizing the substantial differences in the DHFR and DHPS genes among P. carinii from different host species has important implications for drug discovery and the development of new diagnostic methods.
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Ma L, Kovacs JA. Genetic analysis of multiple loci suggests that mutations in the Pneumocystis carinii f. sp. hominis dihydropteroate synthase gene arose independently in multiple strains. Antimicrob Agents Chemother 2001; 45:3213-5. [PMID: 11600382 PMCID: PMC90808 DOI: 10.1128/aac.45.11.3213-3215.2001] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
To determine if mutations in the dihydropteroate synthase (DHPS) gene of Pneumocystis carinii f. sp. hominis arose in a single strain that was subsequently widely disseminated, we examined four genomic regions of 22 P. carinii clinical isolates selected based on the absence or presence of mutations in the DHPS gene. By single-strand conformation polymorphism and DNA sequencing, we found varying genotypes for each of the four regions in isolates with DHPS mutations, suggesting that these mutations occurred independently in multiple strains of P. carinii. This suggests that exposure to sulfa will select for these mutations in diverse strains.
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Kutty G, Ma L, Kovacs JA. Characterization of the expression site of the major surface glycoprotein of human-derived Pneumocystis carinii. Mol Microbiol 2001; 42:183-93. [PMID: 11679077 DOI: 10.1046/j.1365-2958.2001.02620.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The major surface glycoprotein (MSG) of Pneumocystis carinii, a pathogen responsible for pulmonary infection in AIDS and other immunocompromised patients, is an abundant surface protein that potentially allows the organism to evade host defences by antigenic variation. MSG is encoded by a multicopy gene family; in two specific forms of rat-derived P. carinii, regulation of MSG expression uses a single expression site, termed the upstream conserved sequence (UCS), through two related but distinct mechanisms. In the current study, the UCS of the MSG from human-derived P. carinii was obtained using an RNA ligase-mediated rapid amplification of cDNA ends technique. Southern blot analysis demonstrated that the UCS was present in a single copy per genome, whereas multiple copies of the downstream MSG gene were present. Sequencing and restriction fragment length polymorphism analysis of polymerase chain reaction products amplified from pulmonary samples of patients with P. carinii pneumonia demonstrated that multiple MSG genes were expressed in a given host, and that different patterns of MSG expression were seen among different patients. Tandem repeats present in the single intron occurred with varying frequency in different patient isolates, potentially providing a new method for typing human isolates. Thus, human-derived P. carinii regulates MSG expression in a manner similar to P. carinii f. sp. carinii and, in immunosuppressed patients, in whom immune pressures that probably drive antigenic variation are functioning inadequately, P. carinii can express a broad repertoire of MSG variants.
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Sereti I, Herpin B, Metcalf JA, Stevens R, Baseler MW, Hallahan CW, Kovacs JA, Davey RT, Lane HC. CD4 T cell expansions are associated with increased apoptosis rates of T lymphocytes during IL-2 cycles in HIV infected patients. AIDS 2001; 15:1765-75. [PMID: 11579237 DOI: 10.1097/00002030-200109280-00004] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE AND DESIGN In an attempt to determine the mechanisms underlying the CD4 T cell expansions in patients receiving intermittent interleukin (IL)-2, a cohort of 10 HIV infected patients were studied during a 5-day cycle of IL-2 to measure rates of apoptosis, the expression of activation markers in CD4 and CD8 T cell subsets and the serum levels of proinflammatory cytokines. All patients were receiving highly active antiretroviral therapy. METHODS Peripheral blood mononuclear cells were tested pre- and at the completion of IL-2 treatment with annexin V/7-AAD for the measurement of apoptosis. Phenotypic analyses of T lymphocytes were performed in parallel. Serum levels of interferon (IFN)gamma, granulocyte-macrophage colony stimulating factor, IL-6 and tumor necrosis factor (TNF)alpha were tested by enzyme-linked immunosorbent assay. RESULTS IL-2 increased the spontaneous apoptosis rates of CD4 and CD8 T lymphocytes (P = 0.003). Expression of HLA-DR, CD38 and CD95 increased on both CD4 and CD8 T lymphocytes whereas CD25 induction was observed exclusively on CD4 T cells. Significant increases of serum IL-6 and TNFalpha levels were noted in all patients whereas viral loads remained unchanged. CONCLUSION Administration of IL-2 for 5 days in HIV infected patients leads to enhanced apoptosis of both CD4 and CD8 T cells despite an eventual increase of the CD4 T cell count. A profound activation state with induction of activation markers on T cells and high levels of TNFalpha and IL-6 accompanies the increased apoptosis during the IL-2 cycle. These data suggest that the CD4 expansions seen in the context of intermittent IL-2 therapy are the net result of increases in both cell proliferation and cell death.
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Kovacs JA, Vogel S, Metcalf JA, Baseler M, Stevens R, Adelsberger J, Lempicki R, Hengel RL, Sereti I, Lambert L, Dewar RL, Davey RT, Walker RE, Falloon J, Polis MA, Masur H, Lane HC. Interleukin-2 induced immune effects in human immunodeficiency virus-infected patients receiving intermittent interleukin-2 immunotherapy. Eur J Immunol 2001; 31:1351-60. [PMID: 11465092 DOI: 10.1002/1521-4141(200105)31:5<1351::aid-immu1351>3.0.co;2-9] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
To characterize the immunological effects of intermittent IL-2 therapy, which leads to selective increases in CD4+ T lymphocytes in HIV-infected patients, 11 patients underwent extensive immunological evaluation. While IL-2 induced changes in both CD4+ and CD8+ cell number acutely, only CD4+ cells showed sustained increases following discontinuation of IL-2. Transient increases in expression of the activation markers CD38 and HLA-DR were seen on both CD4+ and CD8+ cells, but CD25 (a chain of the IL-2 receptor) increased exclusively on CD4+ cells. This increase in CD25 expression was sustained for months following discontinuation of IL-2, and was seen in naive as well as memory cells. IL-2 induced cell proliferation, but tachyphylaxis to these proliferative effects developed after 1 week despite continued IL-2 administration. It thus appears that sustained CD25 expression selectively on CD4+ cells is a critical component of the immunological response to IL-2, and that intermittent administration of IL-2 is necessary to overcome the tachyphylaxis to IL-2-induced proliferation.
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Miller KD, Spooner K, Herpin BR, Rock-Kress D, Metcalf JA, Davey RT, Falloon J, Kovacs JA, Polis MA, Walker RE, Masur H, Lane HC. Immunotherapy of HIV-infected patients with intermittent interleukin-2: effects of cycle frequency and cycle duration on degree of CD4(+) T-lymphocyte expansion. Clin Immunol 2001; 99:30-42. [PMID: 11286539 DOI: 10.1006/clim.2001.5001] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The ability of IL-2 to induce expansion of the CD4(+) T lymphocyte pool has made it the most studied cytokine in the treatment of HIV infection. The majority of trials have used an empirical regimen of 5-day IL-2 cycles given every 8 weeks--a regimen based upon early pharmacodynamic studies and patient preference. To better define optimal duration and frequency of cycles, a randomized trial was conducted in which patients who received this "standard" regimen were compared to patients who received cycles of variable duration (based on individual patterns of cell cycle progression) and to patients who received cycles of variable frequency (based on individual CD4(+) T lymphocyte responses to previous cycles). Twenty-two patients with HIV-1 infection and CD4(+) T lymphocyte counts > 200 cells/mm(3) were randomized to one of three treatment groups for 32 weeks of study. Eight participants received four 5-day IL-2 cycles (controls) every 8 weeks; 7 participants received four cycles of longer duration (mean 7.7-days); and 7 participants received an increased frequency of 5-day cycles (every 4.1 weeks on average). All three groups experienced significant increases in mean CD4(+) T lymphocytes. However, there were no statistically significant differences in CD4(+) T lymphocyte increases between the group that received longer cycles (median increase 239 cells/mm(3), P = 0.78) or between the group that received more frequent cycles (median increase 511 cells/mm(3), P = 0.54) and the control group (median 284 cells/mm(3)). HIV-1 viral loads decreased during the study period in all three groups. Our inability to demonstrate a significant advantage of increased frequency or duration of IL-2 administration provides corroborating experimental evidence for the use of an IL-2 regimen consisting of 5-day cycles administered no more frequently than every 8 weeks in future clinical trials aimed at expanding the CD4(+) T lymphocyte pool.
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Ma L, Kovacs JA. Rapid detection of mutations in the human-derived Pneumocystis carinii dihydropteroate synthase gene associated with sulfa resistance. Antimicrob Agents Chemother 2001; 45:776-80. [PMID: 11181359 PMCID: PMC90372 DOI: 10.1128/aac.45.3.776-780.2001] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Recent studies have shown that point mutations in the dihydropteroate synthase (DHPS) gene of human-derived Pneumocystis carinii are related to exposure to sulfa drugs and possibly represent the emergence of sulfa resistance. We developed a simple single-strand conformation polymorphism (SSCP) method to permit rapid detection of these mutations. With plasmid constructs, SSCP was able to detect as little as 10% of a minority population. The SSCP assay was compared to direct sequencing for typing the DHPS gene by examining 37 clinical isolates with known DHPS sequences and 41 clinical isolates with unknown DHPS sequences. The typing results were consistent between these two methods for all isolates except 11 in which mutations were detected by SSCP but not by direct sequencing. Sequencing of individual clones after subcloning confirmed the presence of mutations in a minority population as determined by SSCP. SSCP is a very simple and sensitive method for rapid identification of P. camii DHPS mutations.
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Lempicki RA, Kovacs JA, Baseler MW, Adelsberger JW, Dewar RL, Natarajan V, Bosche MC, Metcalf JA, Stevens RA, Lambert LA, Alvord WG, Polis MA, Davey RT, Dimitrov DS, Lane HC. Impact of HIV-1 infection and highly active antiretroviral therapy on the kinetics of CD4+ and CD8+ T cell turnover in HIV-infected patients. Proc Natl Acad Sci U S A 2000; 97:13778-83. [PMID: 11095734 PMCID: PMC17652 DOI: 10.1073/pnas.250472097] [Citation(s) in RCA: 136] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
To evaluate the effects of HIV infection on T cell turnover, we examined levels of DNA synthesis in lymph node and peripheral blood mononuclear cell subsets by using ex vivo labeling with BrdUrd. Compared with healthy controls (n = 67), HIV-infected patients (n = 57) had significant increases in the number and fraction of dividing CD4(+) and CD8(+) T cells. Higher percentages of dividing CD4(+) and CD8(+) T cells were noted in patients with the higher viral burdens. No direct correlation was noted between rates of T cell turnover and CD4(+) T cell counts. Marked reductions in CD4(+) and CD8(+) T cell proliferation were seen in 11/11 patients 1-12 weeks after initiation of highly active antiretroviral therapy (HAART). These reductions persisted for the length of the study (16-72 weeks). Decreases in naive T cell proliferation correlated with increases in the levels of T cell receptor rearrangement excision circles. Division of CD4(+) and CD8(+) T cells increased dramatically in association with rapid increases in HIV-1 viral loads in 9/9 patients 5 weeks after termination of HAART and declined to pre-HAART-termination levels 8 weeks after reinitiation of therapy. These data are consistent with the hypothesis that HIV-1 infection induces a viral burden-related, global activation of the immune system, leading to increases in lymphocyte proliferation.
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Ma L, Kovacs JA. Expression and characterization of recombinant human-derived Pneumocystis carinii dihydrofolate reductase. Antimicrob Agents Chemother 2000; 44:3092-6. [PMID: 11036028 PMCID: PMC101608 DOI: 10.1128/aac.44.11.3092-3096.2000] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Dihydrofolate reductase (DHFR) is the target of trimethoprim (TMP), which has been widely used in combination with sulfa drugs for treatment and prophylaxis of Pneumocystis carinii pneumonia. While the rat-derived P. carinii DHFR has been well characterized, kinetic studies of human-derived P. carinii DHFR, which differs from rat-derived P. carinii DHFR by 38% in amino acid sequence, have not been reported to date. Here we report on the expression and kinetic characterization of the recombinant human-derived P. carinii DHFR. The 618-bp coding sequence of the human-derived P. carinii DHFR gene was expressed in Escherichia coli. As determined by sodium dodecyl sulfate-polyacrylamide gel eletrophoresis, the purified enzyme had a molecular mass of 25 kDa, consistent with that predicted from the DNA sequence. Kinetic analysis showed that the K(m) values for dihydrofolate and NADPH were 2.7 +/- 0.3 and 14.0 +/- 4.3 microM, respectively, which are similar to those reported for rat-derived P. carinii DHFR. Inhibition studies revealed that both TMP and pyrimethamine were poor inhibitors of human-derived P. carinii DHFR, with K(i) values of 0.28 +/- 0.08 and 0.065 +/- 0.005 microM, respectively, while trimetrexate and methotrexate were potent inhibitors, with K(i) values of 0.23 +/- 0.03 and 0.016 +/- 0.004 nM, respectively. The availability of purified recombinant enzyme in large quantities should facilitate the identification of antifolate inhibitors with greater potency and higher selectivity for human-derived P. carinii DHFR.
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Kovacs JA, Imamichi H, Vogel S, Metcalf JA, Dewar RL, Baseler M, Stevens R, Adelsberger J, Lambert L, Davey RT, Walker RE, Falloon J, Polis MA, Masur H, Lane HC. Effects of intermittent interleukin-2 therapy on plasma and tissue human immunodeficiency virus levels and quasi-species expression. J Infect Dis 2000; 182:1063-9. [PMID: 10979900 DOI: 10.1086/315821] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2000] [Revised: 06/15/2000] [Indexed: 11/03/2022] Open
Abstract
To characterize the effects of intermittent interleukin (IL)-2 therapy on human immunodeficiency virus (HIV), 11 patients underwent detailed virological evaluation during a year of IL-2 therapy. Six patients showed a >0.5 log increase in plasma HIV during at least 1 IL-2 cycle, with 2 experiencing an increase in >50% of cycles. Three of the remaining 5 patients had a >0.5 log decrease during at least 1 IL-2 cycle, and the remaining patients exhibited <0.5 log changes. No changes in lymphoid (tonsil) levels of HIV were seen during the year. Quasi-species analysis in a separate cohort demonstrated that the virus induced by IL-2 most commonly resembled pre-IL-2 plasma quasi species. Thus, intermittent IL-2 does not result in sustained increases in either plasma or tissue levels of HIV and does not result in sustained expression of a previously silent quasi species.
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Orenstein JM, Bhat N, Yoder C, Fox C, Polis MA, Metcalf JA, Kovacs JA, Falloon J, Walker RE, Masur H, Lane HC, Davey RT. Rapid activation of lymph nodes and mononuclear cell HIV expression upon interrupting highly active antiretroviral therapy in patients after prolonged viral suppression. AIDS 2000; 14:1709-15. [PMID: 10985306 DOI: 10.1097/00002030-200008180-00004] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To compare the architecture and HIV-1 RNA and Gag p24 protein expression in lymph nodes (LN) excised from individuals during chronic highly active antiretroviral therapy (HAART) with LN removed from the same patient after plasma virus rebound following the interruption of HAART. MATERIALS AND METHODS Six HIV-1-infected patients on HAART, with CD4 cell counts greater than 350 cells/microl, and plasma HIV-1 RNA less than 50 copies/ml, underwent inguinal LN excision upon discontinuation of HAART, and again after rebound of plasma virus. Lymph nodes were evaluated by immunohistochemical staining for Gag p24 antigen and Ki67, in-situ hybridization for HIV-1 RNA and H3-histone, and transmission electron microscopy (TEM). RESULTS LN at baseline were quiescent to mildly hyperplastic and generally contained more primary than secondary follicles. Only one LN had detectable follicular dendritic cell (FDC)-associated p24 antigen, none had HIV RNA. Few mononuclear cells (MNC) expressed RNA or p24 antigen. Plasma virus at the second biopsy ranged from 329 to 3.2 x 10(6) copies/ml. CD4 cell count decline ranged from 5 to 51% during drug hiatus, and was greatest in patients with highest viral rebound. Four of six of the second LN were more hyperplastic than the initial LN, two showed paracortical hyperplasia. MNC expression of HIV RNA in the second LN paralleled the level of plasma viremia. Increased Ki67 and H3-histone signal occurred in the second LN. CONCLUSION Quiescent LN from individuals on HAART rapidly become hyperplastic and activated within 1-2 months after treatment interruption. As in acute HIV infection, virus expression by LN MNC parallels the rebound in plasma viremia and fall in CD4 cell count.
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Miller KD, Cameron M, Wood LV, Dalakas MC, Kovacs JA. Lactic acidosis and hepatic steatosis associated with use of stavudine: report of four cases. Ann Intern Med 2000; 133:192-6. [PMID: 10906833 DOI: 10.7326/0003-4819-133-3-200008010-00010] [Citation(s) in RCA: 168] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND An association between use of zidovudine and didanosine and a rare but life-threatening syndrome of hepatic steatosis, lactic acidosis, and myopathy has been reported. OBJECTIVE To describe the syndrome of hepatic steatosis, lactic acidosis, and myopathy in four patients taking stavudine. DESIGN Case series. SETTING A community hospital in Washington, D.C., and National Institutes of Health Clinical Center, Bethesda, Maryland. PATIENTS Two men and two women with HIV-1 infection who were taking stavudine presented with lactic acidosis and elevated levels of aminotransferases. All patients required intensive care. MEASUREMENTS Levels of lactic acid, alanine aminotransferase, aspartate aminotransferase, amylase, and lipase; computed tomography of the abdomen; liver biopsy (two patients); and muscle biopsy (two patients). RESULTS Histologic findings consistent with mitochondrial injury confirmed the diagnosis of hepatic or muscle abnormality. CONCLUSION Because hepatic steatosis may be life-threatening, physicians should consider it as a possible cause of elevated hepatic aminotransferase levels among patients taking stavudine.
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Emery S, Capra WB, Cooper DA, Mitsuyasu RT, Kovacs JA, Vig P, Smolskis M, Saravolatz LD, Lane HC, Fyfe GA, Curtin PT. Pooled analysis of 3 randomized, controlled trials of interleukin-2 therapy in adult human immunodeficiency virus type 1 disease. J Infect Dis 2000; 182:428-34. [PMID: 10915072 DOI: 10.1086/315736] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/1999] [Revised: 04/24/2000] [Indexed: 11/03/2022] Open
Abstract
We collected human immunodeficiency virus (HIV) disease progression, survival, most recent CD4 cell count, and plasma HIV RNA levels from patients (n=157) who participated in randomized clinical trials of interleukin (IL)-2 that commenced before 1995. Data were available for 155 (99%) patients. Statistical analyses were based on the intention-to-treat principle. Median follow-up was 28 months and 30 months for control and IL-2 patients, respectively. Twenty-five (16%) patients developed AIDS or died during follow-up (16 control patients vs. 9 IL-2 patients; R2=0.57; P=.22). Mean change from baseline CD4 cell count was significantly higher in patients randomized to receive IL-2 (368 vs. 153 cells/microL; P=.003). Mean change from baseline plasma HIV RNA was significantly lower in patients randomized to receive IL-2 (-0.98 vs. -0.63 log copies/mL; P=.004). Significant improvements in CD4 cell count and plasma HIV RNA in recipients of IL-2 relative to control patients were associated with a nonsignificant trend toward improved clinical outcome.
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Walker RE, Bechtel CM, Natarajan V, Baseler M, Hege KM, Metcalf JA, Stevens R, Hazen A, Blaese RM, Chen CC, Leitman SF, Palensky J, Wittes J, Davey RT, Falloon J, Polis MA, Kovacs JA, Broad DF, Levine BL, Roberts MR, Masur H, Lane HC. Long-term in vivo survival of receptor-modified syngeneic T cells in patients with human immunodeficiency virus infection. Blood 2000; 96:467-74. [PMID: 10887107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023] Open
Abstract
To study human immunodeficiency virus (HIV)-specific cellular immunity in vivo, we transferred syngeneic lymphocytes after ex vivo expansion and transduction with a chimeric receptor gene (CD4/CD3-zeta) between identical twins discordant for HIV infection. Single and multiple infusions of 10(10) genetically modified CD8(+) T cells resulted in peak fractions in the circulation of approximately 10(4) to 10(5) modified cells/10(6) mononuclear cells at 24 to 48 hours, followed by 2- to 3-log declines by 8 weeks. In an effort to provide longer high-level persistence of the transferred cells and possibly enhance anti-HIV activity, we administered a second series of infusions in which both CD4(+ )and CD8(+) T cells were engineered to express the chimeric receptor and were costimulated ex vivo with beads coated with anti-CD3 and anti-CD28. Sustained fractions of approximately 10(3) to 10(4) modified cells/10(6) total CD4(+) or CD8(+) cells persisted for at least 1 year. Assessment of in vivo trafficking of the transferred cells by lymphoid tissue biopsies revealed the presence of modified cells in proportions equivalent to or below those in the circulation. The cell infusions were well tolerated and were not associated with substantive immunologic or virologic changes. Thus, adoptive transfer of genetically modified HIV-antigen-specific T cells was safe. Sustained survival in the circulation was achieved when modified CD4(+ )and CD8(+) T cells were infused together after ex vivo costimulation, indicating the important role played by antigen-specific CD4(+) T cells in providing "help" to cytotoxic effectors. (Blood. 2000;96:467-474)
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Kovacs JA, Masur H. Prophylaxis against opportunistic infections in patients with human immunodeficiency virus infection. N Engl J Med 2000; 342:1416-29. [PMID: 10805828 DOI: 10.1056/nejm200005113421907] [Citation(s) in RCA: 172] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Weissman D, Dybul M, Daucher MB, Davey RT, Walker RE, Kovacs JA. Interleukin-2 up-regulates expression of the human immunodeficiency virus fusion coreceptor CCR5 by CD4+ lymphocytes in vivo. J Infect Dis 2000; 181:933-8. [PMID: 10720515 DOI: 10.1086/315303] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Intermittent interleukin-2 (IL-2) therapy can substantially increase CD4+ T cell counts of human immunodeficiency virus (HIV)-infected subjects. Administration of IL-2 led to transient up-regulation of CCR5 on CD4+ T cells; up to 87% of CD4+ cells expressed CCR5 after a 5-day cycle, with return to baseline levels within 2 weeks. Unlike in vitro studies, CCR5 was coexpressed with CD45RA and CXCR4 on CD4+ T cells after IL-2 therapy. The observed increase in coreceptor expression was not associated with detectable increases in viral replication. IL-2 therapy induced CCR5 expression in >90% of circulating memory CD4+ T cells, determined to be a long-term reservoir of HIV, suggesting significant activation of these cells. These studies demonstrate that levels of expression of HIV coreceptors alone do not always correlate with HIV replication in vivo and that IL-2 therapy activates a majority of memory T cells in the circulation and likely throughout the immune system.
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Angus CW, Klivington-Evans D, Dubey JP, Kovacs JA. Immunization with a DNA plasmid encoding the SAG1 (P30) protein of Toxoplasma gondii is immunogenic and protective in rodents. J Infect Dis 2000; 181:317-24. [PMID: 10608781 DOI: 10.1086/315186] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Immunization with DNA can induce humoral and cell-mediated immune responses, both of which are important in conferring immunity to Toxoplasma gondii. The efficacy of genetic vaccination with a cDNA encoding the T. gondii SAG1 (P30) surface antigen was evaluated. Sera of immunized mice showed recognition of T. gondii tachyzoites by immunofluorescence and exhibited high titers of antibody to SAG1 by ELISA. SAG1-stimulated splenocytes from vaccinated mice produced primarily interferon-gamma and interleukin-2. Vaccinated mice survived challenge with 80 tissue cysts of ME49 strain, whereas all control mice died; challenge with 20 tissue cysts resulted in fewer brain cysts, compared with controls. Challenge of vaccinated rats with VEG strain oocysts resulted in a reduction in brain cysts. No protection was observed when mice were challenged with the highly virulent RH strain tachyzoites. These results suggest that nucleic acid vaccination can provide protection against T. gondii infection in mice.
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Davey RT, Bhat N, Yoder C, Chun TW, Metcalf JA, Dewar R, Natarajan V, Lempicki RA, Adelsberger JW, Miller KD, Kovacs JA, Polis MA, Walker RE, Falloon J, Masur H, Gee D, Baseler M, Dimitrov DS, Fauci AS, Lane HC. HIV-1 and T cell dynamics after interruption of highly active antiretroviral therapy (HAART) in patients with a history of sustained viral suppression. Proc Natl Acad Sci U S A 1999; 96:15109-14. [PMID: 10611346 PMCID: PMC24781 DOI: 10.1073/pnas.96.26.15109] [Citation(s) in RCA: 635] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Identifying the immunologic and virologic consequences of discontinuing antiretroviral therapy in HIV-infected patients is of major importance in developing long-term treatment strategies for patients with HIV-1 infection. We designed a trial to characterize these parameters after interruption of highly active antiretroviral therapy (HAART) in patients who had maintained prolonged viral suppression on antiretroviral drugs. Eighteen patients with CD4(+) T cell counts >/= 350 cells/microliter and viral load below the limits of detection for >/=1 year while on HAART were enrolled prospectively in a trial in which HAART was discontinued. Twelve of these patients had received prior IL-2 therapy and had low frequencies of resting, latently infected CD4 cells. Viral load relapse to >50 copies/ml occurred in all 18 patients independent of prior IL-2 treatment, beginning most commonly during weeks 2-3 after cessation of HAART. The mean relapse rate constant was 0.45 (0.20 log(10) copies) day(-1), which was very similar to the mean viral clearance rate constant after drug resumption of 0.35 (0.15 log(10) copies) day(-1) (P = 0.28). One patient experienced a relapse delay to week 7. All patients except one experienced a relapse burden to >5,000 RNA copies/ml. Ex vivo labeling with BrdUrd showed that CD4 and CD8 cell turnover increased after withdrawal of HAART and correlated with viral load whereas lymphocyte turnover decreased after reinitiation of drug treatment. Virologic relapse occurs rapidly in patients who discontinue suppressive drug therapy, even in patients with a markedly diminished pool of resting, latently infected CD4(+) T cells.
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Ma L, Borio L, Masur H, Kovacs JA. Pneumocystis carinii dihydropteroate synthase but not dihydrofolate reductase gene mutations correlate with prior trimethoprim-sulfamethoxazole or dapsone use. J Infect Dis 1999; 180:1969-78. [PMID: 10558954 DOI: 10.1086/315148] [Citation(s) in RCA: 116] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Recent studies of the human Pneumocystis carinii dihydropteroate synthase (DHPS) gene suggest that P. carinii is developing resistance to sulfamethoxazole (SMX) and dapsone. To explore whether P. carinii is also developing resistance to trimethoprim (TMP), the human P. carinii dihydrofolate reductase (DHFR) gene was cloned, DHFR and DHPS genes in 37 P. carinii isolates from 35 patients were sequenced, and the relationship between TMP-SMX or dapsone use and gene mutations was analyzed. The DHFR gene sequences were identical in all isolates except 1 with a synonymous substitution. In contrast, the DHPS gene sequences showed mutations in 16 of the 37 isolates; prior sulfa/sulfone prophylaxis was associated with the presence of these mutations (P<.001). In addition to suggesting that there is less selective pressure on DHFR than on DHPS, this study reinforces the hypothesis that mutations in the DHPS gene are likely involved in the development of sulfa resistance in P. carinii.
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