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Goulder PJ, Lechner F, Klenerman P, McIntosh K, Walker BD. Characterization of a novel respiratory syncytial virus-specific human cytotoxic T-lymphocyte epitope. J Virol 2000; 74:7694-7. [PMID: 10906229 PMCID: PMC112296 DOI: 10.1128/jvi.74.16.7694-7697.2000] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2000] [Accepted: 05/17/2000] [Indexed: 11/20/2022] Open
Abstract
Respiratory syncytial virus (RSV) infection is a major cause of morbidity in childhood worldwide. The first human RSV-specific cytotoxic T-lymphocyte epitope to be defined is described. This HLA B7-restricted epitope in nucleoprotein (NP) was detectable in four healthy, B7-positive adult subjects using B7-RSV-NP tetrameric complexes to stain CD8(+) T cells.
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77
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Brander C, Walker BD. Modulation of host immune responses by clinically relevant human DNA and RNA viruses. Curr Opin Microbiol 2000; 3:379-86. [PMID: 10972498 DOI: 10.1016/s1369-5274(00)00108-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Numerous mechanisms allow viruses to evade host immune surveillance, and new evasion strategies continue to be identified. In addition to interference with antigen processing and presentation, direct viral modulation of host immune responses can also be achieved by altering the host cytokine milieu and the development of immunoregulatory cells. A better understanding of these viral evasion strategies will help to define critical host defense mechanisms and will lead to novel immune-based therapeutic strategies in the future.
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78
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Tie H, Walker BD, Singleton CB, Valenzuela SM, Bursill JA, Wyse KR, Breit SN, Campbell TJ. Inhibition of HERG potassium channels by the antimalarial agent halofantrine. Br J Pharmacol 2000; 130:1967-75. [PMID: 10952689 PMCID: PMC1572249 DOI: 10.1038/sj.bjp.0703470] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Halofantrine is a widely used antimalarial agent which has been associated with prolongation of the 'QT interval' of the electrocardiogram (ECG), torsades de pointes and sudden death. Whilst QT prolongation is consistent with halofantrine-induced increases in cardiac ventricular action potential duration, the cellular mechanism for these observations has not been previously reported. The delayed rectifier potassium channel, I(Kr), is a primary site of action of drugs causing QT prolongation and is encoded by the human-ether-a-go-go-related gene (HERG). We examined the effects of halofantrine on HERG potassium channels stably expressed in Chinese hamster ovary (CHO-K1) cells. Halofantrine blocked HERG tail currents elicited on repolarization to -60 mV from +30 mV with an IC(50) of 196.9 nM. The therapeutic plasma concentration range for halofantrine is 1.67-2.98 microM. Channel inhibition by halofantrine exhibited time-, voltage- and use-dependence. Halofantrine did not alter the time course of channel activation or deactivation, but inactivation was accelerated and there was a 20 mV hyperpolarizing shift in the mid-activation potential of steady-state inactivation. Block was enhanced by pulses that render channels inactivated, and channel blockade increased with increasing duration of depolarizing pulses. We conclude that HERG channel inhibition by halofantrine is the likely underlying cellular mechanism for QT prolongation. Our data suggest preferential binding of halofantrine to the open and inactivated channel states.
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79
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Goulder PJ, Rowland-Jones SL, McMichael AJ, Walker BD. Anti-HIV cellular immunity: recent advances towards vaccine design. AIDS 2000; 13 Suppl A:S121-36. [PMID: 10885771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
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80
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Severino ME, Sipsas NV, Nguyen PT, Kalams SA, Walker BD, Johnson RP, Yang OO. Inhibition of human immunodeficiency virus type 1 replication in primary CD4(+) T lymphocytes, monocytes, and dendritic cells by cytotoxic T lymphocytes. J Virol 2000; 74:6695-9. [PMID: 10864688 PMCID: PMC112184 DOI: 10.1128/jvi.74.14.6695-6699.2000] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We demonstrate that human immunodeficiency virus type 1 (HIV-1)-specific CD8(+) cytotoxic T lymphocytes (CTL) suppress HIV-1 replication in primary lymphocytes, monocytes, and dendritic cells individually. Viral inhibition is significantly diminished in lymphocyte-dendritic cell clusters, suggesting that these clusters in vivo could be sites where viral replication is more difficult to control by CTL.
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81
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82
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Goulder PJ, Tang Y, Pelton SI, Walker BD. HLA-B57-restricted cytotoxic T-lymphocyte activity in a single infected subject toward two optimal epitopes, one of which is entirely contained within the other. J Virol 2000; 74:5291-9. [PMID: 10799606 PMCID: PMC110884 DOI: 10.1128/jvi.74.11.5291-5299.2000] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/1999] [Accepted: 02/29/2000] [Indexed: 11/20/2022] Open
Abstract
Viral peptides are recognized by cytotoxic T lymphocytes (CTL) as a complex with major histocompatibility complex (MHC) class I molecules, but the extent to which a single HLA allele can accommodate epitope peptides of different length and sequence is not well characterized. Here we report the identification of clonal CTL responses from the same donor that independently recognize one of two HLA-B57-restricted epitopes, KAFSPEVIPMF (KF11; p24(Gag) residues 30 to 40) and KAFSPEVI (KF8; p24(Gag) residues 30 to 37). Although lysis studies indicated that the KF11 peptide stabilized the HLA-B57-peptide complex more efficiently than the KI8 peptide, strong clonal responses were directed at each epitope. In samples from a second donor, the same phenomenon was observed, in which distinct CTL clones recognized peptide epitopes presented by the same HLA class I allele (in this case, HLA-A3) which were entirely overlapping. These data are relevant to the accurate characterization of CTL responses, which is fundamental to a detailed understanding of MHC class I-restricted immunity. In addition, these studies demonstrate marked differences in the length of peptides presented by HLA-B57, an allele which is associated with nonprogressive human immunodeficiency virus infection.
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83
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Goulder PJ, Brander C, Annamalai K, Mngqundaniso N, Govender U, Tang Y, He S, Hartman KE, O'Callaghan CA, Ogg GS, Altfeld MA, Rosenberg ES, Cao H, Kalams SA, Hammond M, Bunce M, Pelton SI, Burchett SA, McIntosh K, Coovadia HM, Walker BD. Differential narrow focusing of immunodominant human immunodeficiency virus gag-specific cytotoxic T-lymphocyte responses in infected African and caucasoid adults and children. J Virol 2000; 74:5679-90. [PMID: 10823876 PMCID: PMC112056 DOI: 10.1128/jvi.74.12.5679-5690.2000] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2000] [Accepted: 03/28/2000] [Indexed: 01/29/2023] Open
Abstract
Cytotoxic T-lymphocyte (CTL) activity plays a central role in control of viral replication and in determining outcome in cases of human immunodeficiency virus type 1 (HIV-1) infection. Incorporation of important CTL epitope sequences into candidate vaccines is, therefore, vital. Most CTL studies have focused upon small numbers of adult Caucasoid subjects infected with clade-B virus, whereas the global epidemic is most severe in sub-Saharan African populations and predominantly involves clade-C infection in both adults and children. In this study, sensitive enzyme-linked immunospot (elispot) assays have been utilized to identify the dominant Gag-specific CTL epitopes targeted by adults and children infected with clade-B or -C virus. Cohorts evaluated included 44 B-clade-infected Caucasoid American and African American adults and children and 37 C-clade-infected African adults and children from Durban, South Africa. The results show that 3 out of 46 peptides spanning p17(Gag) and p24(Gag) sequences tested contain two-thirds of the dominant Gag-specific epitopes, irrespective of the clade, ethnicity, or age group studied. However, there were distinctive differences between the dominant responses made by Caucasoids and Africans. Dominant responses in Caucasoids were more often within p17(Gag) peptide residues 16 to 30 (38 versus 12%; P < 0.01), while p24(Gag) peptide residues 41 to 60 contained the dominant Gag epitope more often in the African subjects tested (39 versus 4%; P < 0.005). Within this 20-mer p24(Gag), an epitope presented by both B42 and B81 is defined which represents the dominant Gag response in >30% of the total infected population in Durban. This epitope is closely homologous with dominant HIV-2 and simian immunodeficiency virus Gag-specific CTL epitopes. The fine focusing of dominant CTL responses to these few regions of high immunogenicity is of significance to vaccine design.
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84
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85
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Alexander L, Weiskopf E, Greenough TC, Gaddis NC, Auerbach MR, Malim MH, O'Brien SJ, Walker BD, Sullivan JL, Desrosiers RC. Unusual polymorphisms in human immunodeficiency virus type 1 associated with nonprogressive infection. J Virol 2000; 74:4361-76. [PMID: 10756051 PMCID: PMC111953 DOI: 10.1128/jvi.74.9.4361-4376.2000] [Citation(s) in RCA: 131] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Factors accounting for long-term nonprogression may include infection with an attenuated strain of human immunodeficiency virus type 1 (HIV-1), genetic polymorphisms in the host, and virus-specific immune responses. In this study, we examined eight individuals with nonprogressing or slowly progressing HIV-1 infection, none of whom were homozygous for host-specific polymorphisms (CCR5-Delta32, CCR2-64I, and SDF-1-3'A) which have been associated with slower disease progression. HIV-1 was recovered from seven of the eight, and recovered virus was used for sequencing the full-length HIV-1 genome; full-length HIV-1 genome sequences from the eighth were determined following amplification of viral sequences directly from peripheral blood mononuclear cells (PBMC). Longitudinal studies of one individual with HIV-1 that consistently exhibited a slow/low growth phenotype revealed a single amino acid deletion in a conserved region of the gp41 transmembrane protein that was not seen in any of 131 envelope sequences in the Los Alamos HIV-1 sequence database. Genetic analysis also revealed that five of the eight individuals harbored HIV-1 with unusual 1- or 2-amino-acid deletions in the Gag sequence compared to subgroup B Gag consensus sequences. These deletions in Gag have either never been observed previously or are extremely rare in the database. Three individuals had deletions in Nef, and one had a 4-amino-acid insertion in Vpu. The unusual polymorphisms in Gag, Env, and Nef described here were also found in stored PBMC samples taken 3 to 11 years prior to, or in one case 4 years subsequent to, the time of sampling for the original sequencing. In all, seven of the eight individuals exhibited one or more unusual polymorphisms; a total of 13 unusual polymorphisms were documented in these seven individuals. These polymorphisms may have been present from the time of initial infection or may have appeared in response to immune surveillance or other selective pressures. Our results indicate that unusual, difficult-to-revert polymorphisms in HIV-1 can be found associated with slow progression or nonprogression in a majority of such cases.
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MESH Headings
- Amino Acid Sequence
- Animals
- Cells, Cultured
- Chemokine CXCL12
- Chemokines, CXC/genetics
- Disease Progression
- Gene Products, gag/metabolism
- Gene Products, nef/genetics
- Gene Products, nef/physiology
- Gene Products, vpr/metabolism
- Genotype
- HIV Infections/physiopathology
- HIV Infections/virology
- HIV-1/classification
- HIV-1/genetics
- HIV-1/growth & development
- HIV-1/immunology
- HLA Antigens/classification
- HLA Antigens/genetics
- Haplotypes
- Humans
- Macaca mulatta
- Molecular Sequence Data
- Polymorphism, Genetic
- Receptors, CCR2
- Receptors, CCR5/genetics
- Receptors, Chemokine
- Receptors, Cytokine/genetics
- Sequence Homology, Amino Acid
- Simian Immunodeficiency Virus/genetics
- Simian Immunodeficiency Virus/physiology
- gag Gene Products, Human Immunodeficiency Virus
- nef Gene Products, Human Immunodeficiency Virus
- vpr Gene Products, Human Immunodeficiency Virus
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86
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Singleton CB, Walker BD, Campbell TJ. N-3 polyunsaturated fatty acids and cardiac mortality. AUSTRALIAN AND NEW ZEALAND JOURNAL OF MEDICINE 2000; 30:246-51. [PMID: 10833118 DOI: 10.1111/j.1445-5994.2000.tb00815.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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87
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Walker BD. Immune reconstitution: is there a potential role for Filgrastim (r-metHuG-CSF). JOURNAL OF HEMATOTHERAPY & STEM CELL RESEARCH 1999; 8 Suppl 1:S1-2. [PMID: 10596028 DOI: 10.1089/152581699319849] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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88
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Brander C, Yang OO, Jones NG, Lee Y, Goulder P, Johnson RP, Trocha A, Colbert D, Hay C, Buchbinder S, Bergmann CC, Zweerink HJ, Wolinsky S, Blattner WA, Kalams SA, Walker BD. Efficient processing of the immunodominant, HLA-A*0201-restricted human immunodeficiency virus type 1 cytotoxic T-lymphocyte epitope despite multiple variations in the epitope flanking sequences. J Virol 1999; 73:10191-8. [PMID: 10559335 PMCID: PMC113072 DOI: 10.1128/jvi.73.12.10191-10198.1999] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Immune escape from cytotoxic T-lymphocyte (CTL) responses has been shown to occur not only by changes within the targeted epitope but also by changes in the flanking sequences which interfere with the processing of the immunogenic peptide. However, the frequency of such an escape mechanism has not been determined. To investigate whether naturally occurring variations in the flanking sequences of an immunodominant human immunodeficiency virus type 1 (HIV-1) Gag CTL epitope prevent antigen processing, cells infected with HIV-1 or vaccinia virus constructs encoding different patient-derived Gag sequences were tested for recognition by HLA-A*0201-restricted, p17-specific CTL. We found that the immunodominant p17 epitope (SL9) and its variants were efficiently processed from minigene expressing vectors and from six HIV-1 Gag variants expressed by recombinant vaccinia virus constructs. Furthermore, SL9-specific CTL clones derived from multiple donors efficiently inhibited virus replication when added to HLA-A*0201-bearing cells infected with primary or laboratory-adapted strains of virus, despite the variability in the SL9 flanking sequences. These data suggest that escape from this immunodominant CTL response is not frequently accomplished by changes in the epitope flanking sequences.
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MESH Headings
- Adolescent
- Amino Acid Sequence
- Antigen Presentation
- Cell Line, Transformed
- Child
- Child, Preschool
- Epitopes, T-Lymphocyte/genetics
- Epitopes, T-Lymphocyte/immunology
- Gene Products, gag/genetics
- Gene Products, gag/immunology
- Genetic Variation
- Genetic Vectors
- HIV Antigens/genetics
- HIV Antigens/immunology
- HIV Infections/immunology
- HIV Infections/virology
- HIV-1/genetics
- HIV-1/immunology
- HLA-A2 Antigen/immunology
- Humans
- Immunodominant Epitopes/genetics
- Immunodominant Epitopes/immunology
- Molecular Sequence Data
- Mutagenesis, Site-Directed
- Peptides/immunology
- Plasmids
- Recombination, Genetic
- Sequence Homology, Amino Acid
- T-Lymphocytes, Cytotoxic/immunology
- Vaccinia virus
- Viral Proteins
- gag Gene Products, Human Immunodeficiency Virus
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89
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Abstract
Many studies have been designed to address the role of CTL immune escape in HIV-1 infection, but have not given conclusive answers. Now, an elegant longitudinal analysis clearly demonstrates that progression to disease in SIV-infected macaques is associated with evasion of the CTL response (pages 1270-1276).
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90
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Walker BD, Thorburn CW, Kuchar DL. Recurrent atrial electrode displacement complicating a single lead VDD pacing system. Pacing Clin Electrophysiol 1999; 22:1688-91. [PMID: 10598975 DOI: 10.1111/j.1540-8159.1999.tb00391.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We describe an unusual complication of single-lead VDD pacing: recurrent advancement of the atrial bipole into the right ventricle. As a consequence, the patient experienced symptomatic pacemaker-mediated tachycardia and underwent two revision operations to achieve adequate fixation of the lead.
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91
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Mani I, Cao H, Hom D, Johnson JL, Mugerwa RD, Travers KU, Caliendo AM, Walker BD, Kanki PJ. Plasma RNA viral load as measured by the branched DNA and nucleic acid sequence-based amplification assays of HIV-1 subtypes A and D in Uganda. J Acquir Immune Defic Syndr 1999; 22:208-9. [PMID: 10843537 DOI: 10.1097/00126334-199910010-00016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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92
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Little SJ, Daar ES, D'Aquila RT, Keiser PH, Connick E, Whitcomb JM, Hellmann NS, Petropoulos CJ, Sutton L, Pitt JA, Rosenberg ES, Koup RA, Walker BD, Richman DD. Reduced antiretroviral drug susceptibility among patients with primary HIV infection. JAMA 1999; 282:1142-9. [PMID: 10501117 DOI: 10.1001/jama.282.12.1142] [Citation(s) in RCA: 266] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
CONTEXT The transmission of drug-resistant human immunodeficiency virus (HIV) has been documented, but the prevalence of such transmission is unknown. OBJECTIVE To assess the spectrum and frequency of antiretroviral susceptibility among subjects with primary HIV infection. DESIGN, SETTING, AND PATIENTS Retrospective analysis of 141 subjects identified from clinical research centers in 5 major metropolitan areas, enrolled from 1989 to 1998, with HIV seroconversion within the preceding 12 months and no more than 7 days' prior antiretroviral (ARV) therapy. MAIN OUTCOME MEASURES Phenotypic and genotypic ARV susceptibility of HIV from plasma samples. RESULTS The transmission of drug-resistant HIV as assessed by a greater than 10-fold reduction in ARV susceptibility to 1 or more drugs was observed in 3 (2%) of 141 subjects, including to a nonnucleoside reverse transcriptase inhibitor in 1 patient and to a nucleoside reverse transcriptase inhibitor and a protease inhibitor in 2 patients. Population-based sequence analysis of these 3 samples identified multidrug-resistance mutations in reverse transcriptase (M184V, T215Y, K219K/R) and protease (L101/V, K20R, M361, M46I, G48V, L63P, A71T, V771, V82T, 184V, L90M) in the 2 latter patient samples, along with numerous polymorphisms. A reduction in susceptibility of greater than 2.5- to 10-fold to 1 or more drugs was observed in viral isolates from 36 patients (26%). Sequence analysis of these 36 samples identified well-characterized drug resistance mutation in reverse transcriptase and protease in only 1 of these patients. CONCLUSIONS Reductions in drug susceptibility of more than 10-fold were rare among this cohort of recently HIV-infected subjects and were distributed among each of the 3 major classes of ARV drugs tested. Reductions in susceptibility of more than 2.5- to 10-fold to certain ARV drugs of unknown clinical significance were highly prevalent among newly infected patients. Resistance testing may be warranted to monitor the frequency of drug resistance over time and to assess the potential for geographic variability.
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93
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Walker BD, Singleton CB, Bursill JA, Wyse KR, Valenzuela SM, Qiu MR, Breit SN, Campbell TJ. Inhibition of the human ether-a-go-go-related gene (HERG) potassium channel by cisapride: affinity for open and inactivated states. Br J Pharmacol 1999; 128:444-50. [PMID: 10510456 PMCID: PMC1571630 DOI: 10.1038/sj.bjp.0702774] [Citation(s) in RCA: 94] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/1999] [Revised: 05/10/1999] [Accepted: 06/16/1999] [Indexed: 11/08/2022] Open
Abstract
1 Cisapride is a prokinetic agent which has been associated with QT prolongation, torsades de pointes and cardiac arrest. The cellular mechanism for these observations is high affinity blockade of IKr (encoded by HERG). 2 In a chronic transfection model using CHO-K1 cells, cisapride inhibited HERG tail currents after a step to +25 mV with similar potency at room and physiological temperatures (IC50 16. 4 nM at 20-22 degrees C and 23.6 nM at 37 degrees C). 3 Channel inhibition exhibited time-, voltage- and frequency-dependence. In an envelope of tails test, channel blockade increased from 27+/-8% after a 120 ms depolarizing step to 50+/-4% after a 1.0 s step. These findings suggested affinity for open and/or inactivated channel states. 4 Inactivation was significantly accelerated by cisapride in a concentration-dependent manner and there was a small (-7 mV) shift in the voltage dependence of steady state inactivation. 5 Channel blockade by cisapride was modulated by [K+]o, with a 26% reduction in the potency of channel blockade when [K+]o was increased from 1 to 10 mM. 6 In conclusion, HERG channel inhibition by cisapride exhibits features consistent with open and inactivated state binding and is sensitive to external potassium concentration. These features may have significant clinical implications with regard to the mechanism and treatment of cisapride-induced proarrhythmia.
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94
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Kalams SA, Goulder PJ, Shea AK, Jones NG, Trocha AK, Ogg GS, Walker BD. Levels of human immunodeficiency virus type 1-specific cytotoxic T-lymphocyte effector and memory responses decline after suppression of viremia with highly active antiretroviral therapy. J Virol 1999; 73:6721-8. [PMID: 10400770 PMCID: PMC112757 DOI: 10.1128/jvi.73.8.6721-6728.1999] [Citation(s) in RCA: 249] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/1999] [Accepted: 05/07/1999] [Indexed: 11/20/2022] Open
Abstract
Therapeutic suppression of human immunodeficiency virus type 1 (HIV-1) replication may help elucidate interactions between the host cellular immune responses and HIV-1 infection. We performed a detailed longitudinal evaluation of two subjects before and after the start of highly active antiretroviral therapy (HAART). Both subjects had evidence of in vivo-activated and memory cytotoxic T-lymphocyte precursor (CTLp) activity against multiple HIV-1 gene products. After the start of therapy, both subjects had declines in the levels of in vivo-activated HIV-1-specific CTLs and had immediate increases in circulating HIV-1-specific CTL memory cells. With continued therapy, and continued suppression of viral load, levels of memory CTLps declined. HLA A*0201 peptide tetramer staining demonstrated that declining levels of in vivo-activated CTL activity were associated with a decrease in the expression of the CD38(+) activation marker. Transient increases in viral load during continued therapy were associated with increases in the levels of virus-specific CTLps in both individuals. The results were confirmed by measuring CTL responses to discrete optimal epitopes. These studies illustrate the dynamic equilibrium between the host immune response and levels of viral antigen burden and suggest that efforts to augment HIV-1-specific immune responses in subjects on HAART may decrease the incidence of virologic relapse.
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95
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Brander C, Walker BD. T lymphocyte responses in HIV-1 infection: implications for vaccine development. Curr Opin Immunol 1999; 11:451-9. [PMID: 10448136 DOI: 10.1016/s0952-7915(99)80076-4] [Citation(s) in RCA: 97] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Substantial progress has been made over the past year in understanding the cellular immune response in HIV pathogenesis. Cytotoxic T lymphocytes play a critical role in establishing the level of viremia and virus-specific Th cell responses appear to affect the in vivo efficacy of cytotoxic T lymphocytes. Together, these new data provide important insights to refocus efforts aimed at immunotherapeutic interventions and vaccine development.
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96
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Kalams SA, Buchbinder SP, Rosenberg ES, Billingsley JM, Colbert DS, Jones NG, Shea AK, Trocha AK, Walker BD. Association between virus-specific cytotoxic T-lymphocyte and helper responses in human immunodeficiency virus type 1 infection. J Virol 1999; 73:6715-20. [PMID: 10400769 PMCID: PMC112756 DOI: 10.1128/jvi.73.8.6715-6720.1999] [Citation(s) in RCA: 285] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Cellular immune responses are thought to be an important antiviral host defense, but the relationship between virus-specific T-helper and cytotoxic-T-lymphocyte (CTL) responses has not been defined. To investigate a potential link between these responses, we examined functional human immunodeficiency virus type 1 (HIV-1)-specific memory CTL precursor frequencies and p24-specific proliferative responses in a cohort of infected untreated persons with a wide range of viral loads and CD4 cell counts. Levels of p24-specific proliferative responses positively correlated with levels of Gag-specific CTL precursors and negatively correlated with levels of plasma HIV-1 RNA. These data linking the levels of HIV-specific CTL with virus-specific helper cell function during chronic viral infection provide cellular immunologic parameters to guide therapeutic and prophylactic vaccine development.
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97
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Hay CM, Ruhl DJ, Basgoz NO, Wilson CC, Billingsley JM, DePasquale MP, D'Aquila RT, Wolinsky SM, Crawford JM, Montefiori DC, Walker BD. Lack of viral escape and defective in vivo activation of human immunodeficiency virus type 1-specific cytotoxic T lymphocytes in rapidly progressive infection. J Virol 1999; 73:5509-19. [PMID: 10364299 PMCID: PMC112608 DOI: 10.1128/jvi.73.7.5509-5519.1999] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Human immunodeficiency virus type 1 (HIV-1)-specific immune responses over the course of rapidly progressive infection are not well defined. Detailed longitudinal analyses of neutralizing antibodies, lymphocyte proliferation, in vivo-activated and memory cytotoxic T-lymphocyte (CTL) responses, and viral sequence variation were performed on a patient who presented with acute HIV-1 infection, developed an AIDS-defining illness 13 months later, and died 45 months after presentation. Neutralizing-antibody responses remained weak throughout, and no HIV-1-specific lymphocyte proliferative responses were seen even early in the disease course. Strong in vivo-activated CTL directed against Env and Pol epitopes were present at the time of the initial drop in viremia but were quickly lost. Memory CTL against Env and Pol epitopes were detected throughout the course of infection; however, these CTL were not activated in vivo. Despite an initially narrow CTL response, new epitopes were not targeted as the disease progressed. Viral sequencing showed the emergence of variants within the two targeted CTL epitopes; however, viral variants within the immunodominant Env epitope were well recognized by CTL, and there was no evidence of viral escape from immune system detection within this epitope. These data demonstrate a narrowly directed, static CTL response in a patient with rapidly progressive disease. We also show that disease progression can occur in the presence of persistent memory CTL recognition of autologous epitopes and in the absence of detectable escape from CTL responses, consistent with an in vivo defect in activation of CTL.
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98
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Singleton CB, Valenzuela SM, Walker BD, Tie H, Wyse KR, Bursill JA, Qiu MR, Breit SN, Campbell TJ. Blockade by N-3 polyunsaturated fatty acid of the Kv4.3 current stably expressed in Chinese hamster ovary cells. Br J Pharmacol 1999; 127:941-8. [PMID: 10433502 PMCID: PMC1566103 DOI: 10.1038/sj.bjp.0702638] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
1. The Kv4.3 gene is believed to encode a large proportion of the transient outward current (Ito), responsible for the early phase of repolarization of the human cardiac action potential. There is evidence that this current is involved in the dispersion of refractoriness which develops during myocardial ischaemia and which predisposes to the development of potentially fatal ventricular tachyarrhythmias. 2. Epidemiological, clinical, animal, and cellular studies indicate that these arrhythmias may be ameliorated in myocardial ischaemia by n-3 polyunsaturated fatty acids (n-3 PUFA) present in fish oils. 3. We describe stable transfection of the Kv4.3 gene into a mammalian cell line (Chinese hamster ovary cells), and using patch clamp techniques have shown that the resulting current closely resembles human Ito. 4. The current is rapidly activating and inactivating, with both processes being well fit by double exponential functions (time constants of 3.8 +/- 0.2 and 5.3 +/- 0.4 ms for activation and 20.0 +/- 1.2 and 96.6+/-6.7 ms for inactivation at +45 mV at 23 degrees C). Activation and steady state inactivation both show voltage dependence (V1/2 of activation= -6.7+/-2.5 mV, V1,2 of steady state inactivation= -51.3+/-0.2 mV at 23 degrees C). Current inactivation and recovery from inactivation are faster at physiologic temperature (37 degrees C) compared to room temperature (23 degrees C). 5. The n-3 PUFA docosahexaenoic acid blocks the Kv4.3 current with an IC50 of 3.6 micromol L(-1). Blockade of the transient outward current may be an important mechanism by which n-3 PUFA provide protection against the development of ventricular fibrillation during myocardial ischaemia.
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Yang OO, Swanberg SL, Lu Z, Dziejman M, McCoy J, Luster AD, Walker BD, Herrmann SH. Enhanced inhibition of human immunodeficiency virus type 1 by Met-stromal-derived factor 1beta correlates with down-modulation of CXCR4. J Virol 1999; 73:4582-9. [PMID: 10233917 PMCID: PMC112499 DOI: 10.1128/jvi.73.6.4582-4589.1999] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
CXCR4 is a chemokine receptor used by some strains of HIV-1 as an entry coreceptor in association with cell surface CD4 on human cells. In human immunodeficiency virus type 1 (HIV-1)-infected individuals, the appearance of viral isolates with a tropism for CXCR4 (T tropic) has been correlated with late disease progression. The presumed natural ligands for CXCR4 are SDF-1alpha and SDF-1beta, which are proposed to play a role in blocking T-tropic HIV-1 cell entry. Here, we demonstrate that addition of an N-terminal methionine residue to SDF-1beta (Met-SDF-1beta) results in a dramatically enhanced functional activity compared to that of native SDF-1beta. Equivalent concentrations of Met-SDF-1beta are markedly more inhibitory for T-tropic HIV-1 replication than SDF-1beta. A comparison of the biological activities of these two forms of SDF-1beta reveals that Met-SDF-1beta induces a more pronounced intracellular calcium flux yet binds with slightly lower affinity to CXCR4 than SDF-1beta. Down-modulation of CXCR4 is similar after exposure of cells to either chemokine form for 2 h. However, after a 48-h incubation, the surface expression of CXCR4 is much lower for cells treated with Met-SDF-1beta. The enhanced blocking of T-tropic HIV-1 by Met-SDF-1beta appears to be related to prolonged CXCR4 down-modulation.
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Wilson CC, Brown RC, Korber BT, Wilkes BM, Ruhl DJ, Sakamoto D, Kunstman K, Luzuriaga K, Hanson IC, Widmayer SM, Wiznia A, Clapp S, Ammann AJ, Koup RA, Wolinsky SM, Walker BD. Frequent detection of escape from cytotoxic T-lymphocyte recognition in perinatal human immunodeficiency virus (HIV) type 1 transmission: the ariel project for the prevention of transmission of HIV from mother to infant. J Virol 1999; 73:3975-85. [PMID: 10196293 PMCID: PMC104176 DOI: 10.1128/jvi.73.5.3975-3985.1999] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Host immunologic factors, including human immunodeficiency virus (HIV)-specific cytotoxic T lymphocytes (CTL), are thought to contribute to the control of HIV type 1 (HIV-1) replication and thus delay disease progression in infected individuals. Host immunologic factors are also likely to influence perinatal transmission of HIV-1 from infected mother to infant. In this study, the potential role of CTL in modulating HIV-1 transmission from mother to infant was examined in 11 HIV-1-infected mothers, 3 of whom transmitted virus to their offspring. Frequencies of HIV-1-specific human leukocyte antigen class I-restricted CTL responses and viral epitope amino acid sequence variation were determined in the mothers and their infected infants. Maternal HIV-1-specific CTL clones were derived from each of the HIV-1-infected pregnant women. Amino acid substitutions within the targeted CTL epitopes were more frequently identified in transmitting mothers than in nontransmitting mothers, and immune escape from CTL recognition was detected in all three transmitting mothers but in only one of eight nontransmitting mothers. The majority of viral sequences obtained from the HIV-1-infected infant blood samples were susceptible to maternal CTL. These findings demonstrate that epitope amino acid sequence variation and escape from CTL recognition occur more frequently in mothers that transmit HIV-1 to their infants than in those who do not. However, the transmitted virus can be a CTL susceptible form, suggesting inadequate in vivo immune control.
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