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Godkin AJ, Smith KJ, Willis A, Tejada-Simon MV, Zhang J, Elliott T, Hill AV. Naturally processed HLA class II peptides reveal highly conserved immunogenic flanking region sequence preferences that reflect antigen processing rather than peptide-MHC interactions. THE JOURNAL OF IMMUNOLOGY 2001; 166:6720-7. [PMID: 11359828 DOI: 10.4049/jimmunol.166.11.6720] [Citation(s) in RCA: 90] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
MHC class II heterodimers bind peptides 12-20 aa in length. The peptide flanking residues (PFRs) of these ligands extend from a central binding core consisting of nine amino acids. Increasing evidence suggests that the PFRs can alter the immunogenicity of T cell epitopes. We have previously noted that eluted peptide pool sequence data derived from an MHC class II Ag reflect patterns of enrichment not only in the core binding region but also in the PFRS: We sought to distinguish whether these enrichments reflect cellular processes or direct MHC-peptide interactions. Using the multiple sclerosis-associated allele HLA-DR2, pool sequence data from naturally processed ligands were compared with the patterns of enrichment obtained by binding semicombinatorial peptide libraries to empty HLA-DR2 molecules. Naturally processed ligands revealed patterns of enrichment reflecting both the binding motif of HLA-DR2 (position (P)1, aliphatic; P4, bulky hydrophobic; and P6, polar) as well as the nonbound flanking regions, including acidic residues at the N terminus and basic residues at the C terminus. These PFR enrichments were independent of MHC-peptide interactions. Further studies revealed similar patterns in nine other HLA alleles, with the C-terminal basic residues being as highly conserved as the previously described N-terminal prolines of MHC class II ligands. There is evidence that addition of C-terminal basic PFRs to known peptide epitopes is able to enhance both processing as well as T cell activation. Recognition of these allele-transcending patterns in the PFRs may prove useful in epitope identification and vaccine design.
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77
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Jepson A, Fowler A, Banya W, Singh M, Bennett S, Whittle H, Hill AV. Genetic regulation of acquired immune responses to antigens of Mycobacterium tuberculosis: a study of twins in West Africa. Infect Immun 2001; 69:3989-94. [PMID: 11349068 PMCID: PMC98461 DOI: 10.1128/iai.69.6.3989-3994.2001] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The role of genetic factors in clinical tuberculosis is increasingly recognized; how such factors regulate the immune response to Mycobacterium tuberculosis in healthy individuals is unclear. In this study of 255 adult twin pairs residing in The Gambia, West Africa, it is apparent that memory T-cell responses to secreted mycobacterial antigens (85-kDa antigen complex, "short-term culture filtrate," and peptides from the ESAT-6 protein), as well as to the 65-kDa heat shock protein, are subject to effective genetic regulation. The delayed hypersensitivity response to intradermal tuberculin also demonstrates significant genetic variance, while quantitative T-cell and antibody responses to the 38-kDa cell membrane protein appear to be determined largely by environmental factors. Such findings have implications for vaccine development.
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Abstract
Immunogenetic analysis of disease susceptibility has been encouraged by the identification of strong HLA associations with several diseases of uncertain cause. Weaker HLA associations exist with a large number of infectious and non-infectious diseases and the mechanisms of these effects are beginning to be uncovered. Extensive analyses of non-HLA immunogenetic variants have also been undertaken and associations with a variety of genes identified. Genetic linkage analysis of multicase families has recently identified new major susceptibility loci for a few immunologically determined common diseases. However, the greatest potential for the future lies in genome-wide searches for susceptibility genes that individually might have quite modest effects but cumulatively have a large impact on individual risk. This new era of immunogenomics promises to provide key insights into disease pathogenesis and identify multiple molecular targets for intervention strategies.
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79
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Lalvani A, Pathan AA, Durkan H, Wilkinson KA, Whelan A, Deeks JJ, Reece WH, Latif M, Pasvol G, Hill AV. Enhanced contact tracing and spatial tracking of Mycobacterium tuberculosis infection by enumeration of antigen-specific T cells. Lancet 2001; 357:2017-21. [PMID: 11438135 DOI: 10.1016/s0140-6736(00)05115-1] [Citation(s) in RCA: 266] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
BACKGROUND Identification of individuals latently infected with Mycobacterium tuberculosis is an important part of tuberculosis control. The current method, the tuberculin skin test (TST), has poor specificity because of the antigenic cross-reactivity of purified protein derivative (PPD) with M bovis BCG vaccine and environmental mycobacteria. ESAT-6 is a secreted antigen that is highly specific for M tuberculosis complex, but is absent from M bovis BCG. With an enzyme-linked immunospot (ELISPOT) assay for interferon gamma, we have identified ESAT-6-specific T cells as an accurate marker of M tuberculosis infection. METHODS We did a prospective, masked study of 50 healthy contacts, with varying but well defined degrees of exposure to M tuberculosis, who attended an urban contact-tracing clinic. We assessed and compared the efficacy of our assay and TST for detection of symptomless infected individuals by correlation of test results with the degree of exposure to an infectious index case. FINDINGS The ESAT-6 ELISPOT assay results had a strong positive relation with increasing intensity of exposure (odds ratio=9.0 per unit increase in level of exposure [95% CI 2.6--31.6], p=0.001), whereas TST results had a weaker relation with exposure (1.9 [1.0--3.5], p=0.05). By contrast, ELISPOT results were not correlated with BCG vaccination status (p=0.7), whereas TST results were significantly more likely to be positive in BCG-vaccinated contacts (12.1 [1.3--115.7], p=0.03). INTERPRETATION This new antigen-specific T cell-based assay could allow more accurate identification of symptom-free individuals recently exposed to M tuberculosis, and thereby help to improve tuberculosis control.
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80
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Begovich AB, Moonsamy PV, Mack SJ, Barcellos LF, Steiner LL, Grams S, Suraj-Baker V, Hollenbach J, Trachtenberg E, Louie L, Zimmerman P, Hill AV, Stoneking M, Sasazuki T, Konenkov VI, Sartakova ML, Titanji VP, Rickards O, Klitz W. Genetic variability and linkage disequilibrium within the HLA-DP region: analysis of 15 different populations. TISSUE ANTIGENS 2001; 57:424-39. [PMID: 11556967 DOI: 10.1034/j.1399-0039.2001.057005424.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
In order to understand the forces governing the evolution of the genetic diversity in the HLA-DP molecule, polymerase chain reaction (PCR)-based methods were used to characterize genetic variation at the DPA1 and DPB1 loci encoding this heterodimer on 2,807 chromosomes from 15 different populations including individuals of African, Asian, Amerindian, Indian and European origin. These ethnically diverse samples represent a variety of population substructures and include small, isolated populations as well as larger, presumably admixed populations. Ten DPA1 and 39 DPB1 alleles were identified and observed on 87 distinct DP haplotypes, 34 of which were found to be in significant positive linkage disequilibrium in at least one population. Some haplotypes were found in all ethnic groups while others were confined to a single ethnic group or population. Strong positive global linkage disequilibrium (Wn) between DPA1 and DPB1 was present in all 15 populations. The African populations displayed the lowest values of Wn whereas the Amerindian populations displayed near absolute disequilibrium. Analysis of the distribution of haplotypes using the normalized deviate of the Ewens-Watterson homozygosity statistic, F, suggests that DP haplotypes encoding the functional heterodimer are subject to much lower degrees of balancing selection than other loci within the HLA region. Finally, neighbor joining tree analyses demonstrate the power of haplotype diversity for inferring the relationships between the different populations.
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81
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Siddiqui MR, Meisner S, Tosh K, Balakrishnan K, Ghei S, Fisher SE, Golding M, Shanker Narayan NP, Sitaraman T, Sengupta U, Pitchappan R, Hill AV. A major susceptibility locus for leprosy in India maps to chromosome 10p13. Nat Genet 2001; 27:439-41. [PMID: 11279529 DOI: 10.1038/86958] [Citation(s) in RCA: 141] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Leprosy, a chronic infectious disease caused by Mycobacterium leprae, is prevalent in India, where about half of the world's estimated 800,000 cases occur. A role for the genetics of the host in variable susceptibility to leprosy has been indicated by familial clustering, twin studies, complex segregation analyses and human leukocyte antigen (HLA) association studies. We report here a genetic linkage scan of the genomes of 224 families from South India, containing 245 independent affected sibpairs with leprosy, mainly of the paucibacillary type. In a two-stage genome screen using 396 microsatellite markers, we found significant linkage (maximum lod score (MLS) = 4.09, P < 2x10-5) on chromosome 10p13 for a series of neighboring microsatellite markers, providing evidence for a major locus for this prevalent infectious disease. Thus, despite the polygenic nature of infectious disease susceptibility, some major, non-HLA-linked loci exist that may be mapped through obtainable numbers of affected sibling pairs.
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82
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Lalvani A, Pathan AA, McShane H, Wilkinson RJ, Latif M, Conlon CP, Pasvol G, Hill AV. Rapid detection of Mycobacterium tuberculosis infection by enumeration of antigen-specific T cells. Am J Respir Crit Care Med 2001; 163:824-8. [PMID: 11282752 DOI: 10.1164/ajrccm.163.4.2009100] [Citation(s) in RCA: 317] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
There is no reliable means of detecting latent M. tuberculosis infection, and even in patients with active tuberculosis, infection is often unconfirmed. We hypothesized that M. tuberculosis antigen-specific T cells might reliably indicate infection. We enumerated peripheral blood-derived interferon gamma (IFN-gamma)-secreting T cells responding to epitopes from ESAT-6, an antigen that is highly specific for M. tuberculosis complex but absent from BCG, in four groups of individuals. Forty-five of 47 patients with bacteriologically confirmed tuberculosis had ESAT-6-specific IFN-gamma-secreting T cells, compared with four of 47 patients with nontuberculous illnesses, indicating that these T cells are an accurate marker of M. tuberculosis infection. This assay thus has a sensitivity of 96% (95% confidence interval [CI] 92-100) for detecting M. tuberculosis infection in this patient population. By comparison, of the 26 patients with tuberculosis who had a diagnostic tuberculin skin test (TST), only 18 (69%) were positive (p = 0.003). In addition, 22 of 26 (85%) TST-positive exposed household contacts had ESAT-6-specific T cells, whereas zero of 26 unexposed BCG-vaccinated subjects responded. This approach enables rapid detection of M. tuberculosis infection in patients with active tuberculosis and in exposed asymptomatic individuals at high risk of latent infection; it also successfully distinguishes between M. tuberculosis infection and BCG vaccination. This capability may facilitate tuberculosis control in nonendemic regions.
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83
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Lee EA, Flanagan KL, Odhiambo K, Reece WH, Potter C, Bailey R, Marsh K, Pinder M, Hill AV, Plebanski M. Identification of frequently recognized dimorphic T-cell epitopes in plasmodium falciparum merozoite surface protein-1 in West and East Africans: lack of correlation of immune recognition and allelic prevalence. Am J Trop Med Hyg 2001; 64:194-203. [PMID: 11442217 DOI: 10.4269/ajtmh.2001.64.194] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
The merozoite surface protein-1 (MSP1) is the most studied malaria blood-stage vaccine candidate. Lymphokines such as interferon gamma (IFN-gamma) and interleukin 4 (IL-4) may mediate blood-stage specific protection. Here we identify Plasmodiumfalciparum MSP1 T-cell epitopes capable of rapid induction of IFN-gamma and/or IL-4 from peripheral blood mononuclear cells of East and West African donors. Both allelic forms of these novel MSP1 T-cell epitopes were stimulatory. An unusually high numbers of Gambian responders (> 80%) to these epitopes were observed, suggesting that MSPI reactivity may have been underestimated previously in this population. Surprisingly, IFN-gamma responses to allelic T-cell epitopes failed to correlate with differential antigenic exposure in The Gambia compared to Kenya. These results suggest an unexpected level of immunoregulation of IFN-gamma response with variable allelic T-cell reactivity independent of the level of antigenic exposure. Further analysis of the mechanisms determining this response pattern may be required if vaccines are to overcome this allelic reactivity bias in malaria-exposed populations.
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84
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McShane H, Brookes R, Gilbert SC, Hill AV. Enhanced immunogenicity of CD4(+) t-cell responses and protective efficacy of a DNA-modified vaccinia virus Ankara prime-boost vaccination regimen for murine tuberculosis. Infect Immun 2001; 69:681-6. [PMID: 11159955 PMCID: PMC97939 DOI: 10.1128/iai.69.2.681-686.2001] [Citation(s) in RCA: 178] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2000] [Accepted: 10/28/2000] [Indexed: 11/20/2022] Open
Abstract
DNA vaccines whose DNA encodes a variety of antigens from Mycobacterium tuberculosis have been evaluated for immunogenicity and protective efficacy. CD8(+) T-cell responses and protection achieved in other infectious disease models have been optimized by using a DNA immunization to prime the immune system and a recombinant virus encoding the same antigen(s) to boost the response. A DNA vaccine (D) and recombinant modified vaccinia virus Ankara (M) in which the DNA encodes early secreted antigenic target 6 and mycobacterial protein tuberculosis 63 synthesized, and each was found to generate specific gamma interferon (IFN-gamma)-secreting CD4(+) T cells. Enhanced CD4(+) IFN-gamma T-cell responses were produced by both D-M and M-D immunization regimens. Significantly higher levels of IFN-gamma were seen with a D-D-D-M immunization regimen. The most immunogenic regimens were assessed in a challenge study and found to produce protection equivalent to that produced by Mycobacterium bovis BCG. Thus, heterologous prime-boost regimens boost CD4(+) as well as CD8(+) T-cell responses, and the use of heterologous constructs encoding the same antigen(s) may improve the immunogenicity and protective efficacy of DNA vaccines against tuberculosis and other diseases.
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85
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Lalvani A, Nagvenkar P, Udwadia Z, Pathan AA, Wilkinson KA, Shastri JS, Ewer K, Hill AV, Mehta A, Rodrigues C. Enumeration of T cells specific for RD1-encoded antigens suggests a high prevalence of latent Mycobacterium tuberculosis infection in healthy urban Indians. J Infect Dis 2001; 183:469-77. [PMID: 11133379 DOI: 10.1086/318081] [Citation(s) in RCA: 252] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2000] [Revised: 10/27/2000] [Indexed: 11/03/2022] Open
Abstract
Knowledge of the prevalence of latent Mycobacterium tuberculosis infection is crucial for effective tuberculosis control, but tuberculin skin test surveys have major limitations, including poor specificity because of the broad antigenic cross-reactivity of tuberculin. The M. tuberculosis RD1 genomic segment encodes proteins, such as early secretory antigenic target (ESAT)-6, that are absent from M. bovis bacille Calmette-Guérin (BCG) and most environmental mycobacteria. We recently identified circulating ESAT-6-specific T cells as an accurate marker of M. tuberculosis infection. Here, interferon-gamma-secreting T cells specific for peptides derived from ESAT-6 and a second RD1 gene product, CFP10, were enumerated in 100 prospectively recruited healthy adults in Bombay (Mumbai), India. Eighty percent responded to >/=1 antigen, and many donors had high frequencies of T cells that were specific for certain immunodominant peptides. In contrast, of 40 mostly BCG-vaccinated, United Kingdom-resident healthy adults, none responded to either antigen. This study suggests an 80% prevalence of latent M. tuberculosis infection in urban India.
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86
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Smith SM, Brookes R, Klein MR, Malin AS, Lukey PT, King AS, Ogg GS, Hill AV, Dockrell HM. Human CD8+ CTL specific for the mycobacterial major secreted antigen 85A. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2000; 165:7088-95. [PMID: 11120838 DOI: 10.4049/jimmunol.165.12.7088] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The role of CD8(+) CTL in protection against tuberculosis in human disease is unclear. In this study, we stimulated the peripheral blood mononuclear cells of bacillus Calmette-Guérin (BCG)-vaccinated individuals with live Mycobacterium bovis BCG bacilli to establish short-term cell lines and then purified the CD8(+) T cells. A highly sensitive enzyme-linked immunospot (ELISPOT) assay for single cell IFN-gamma release was used to screen CD8(+) T cells with overlapping peptides spanning the mycobacterial major secreted protein, Ag85A. Three peptides consistently induced a high frequency of IFN-gamma responsive CD8(+) T cells, and two HLA-A*0201 binding motifs, P(48-56) and P(242-250), were revealed within the core sequences. CD8(+) T cells responding to the 9-mer epitopes were visualized within fresh blood by ELISPOT using free peptide or by binding of HLA-A*0201 tetrameric complexes. The class I-restricted CD8(+) T cells were potent CTL effector cells that efficiently lysed an HLA-A2-matched monocyte cell line pulsed with peptide as well as autologous macrophages infected with Mycobacterium tuberculosis or recombinant vaccinia virus expressing the whole Ag85A protein. Tetramer assays revealed a 6-fold higher frequency of peptide-specific T cells than IFN-gamma ELISPOT assays, indicating functional heterogeneity within the CD8(+) T cell population. These results demonstrate a previously unrecognized, MHC class I-restricted, CD8(+) CTL response to a major secreted Ag of mycobacteria and supports the use of Ag85A as a candidate vaccine against tuberculosis.
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87
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Cervino AC, Lakiss S, Sow O, Hill AV. Allelic association between the NRAMP1 gene and susceptibility to tuberculosis in Guinea-Conakry. Ann Hum Genet 2000; 64:507-12. [PMID: 11281214 DOI: 10.1046/j.1469-1809.2000.6460507.x] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Forty four families from Guinea-Conakry were analysed to test for association between NRAMP1 (Natural Resistance Associated Macrophage Protein 1) polymorphisms and tuberculosis. Each family included at least one affected sib and one parent. Healthy sibs were also analysed and on average the families included four members. A total of 160 individuals were included in the final dataset. The analysis of association was performed using an extended TDT test, TRANSMlT, to allow for missing information in the parental genotypes. Three polymorphisms in the NRAMP1 gene were typed: a microsatellite (CA) repeat, a 4 bp deletion in the 3' untranslated region and a single nucleotide change in intron 4. The single base change in intron 4 was significantly associated (p = 0.036) with tuberculosis. Our results therefore confirm, using a family-based approach on a newly studied population, the previously reported association between this polymorphism and tuberculosis in a population-based study of West Africans.
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88
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Pathan AA, Wilkinson KA, Wilkinson RJ, Latif M, McShane H, Pasvol G, Hill AV, Lalvani A. High frequencies of circulating IFN-gamma-secreting CD8 cytotoxic T cells specific for a novel MHC class I-restricted Mycobacterium tuberculosis epitope in M. tuberculosis-infected subjects without disease. Eur J Immunol 2000; 30:2713-21. [PMID: 11009107 DOI: 10.1002/1521-4141(200009)30:9<2713::aid-immu2713>3.0.co;2-4] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
MHC class I-restricted CD8 cytotoxic T lymphocytes (CTL) are essential for protective immunity to Mycobacterium tuberculosis in animal models but their role in humans remains unclear. We therefore studied subjects who had successfully contained M. tuberculosis infection in vivo, i.e. exposed healthy household contacts and individuals with inactive self-healed pulmonary tuberculosis. Using the ELISPOT assay for IFN-gamma, we screened peptides from ESAT-6, a secreted antigen that is highly specific for M. tuberculosis. We identified a novel nonamer epitope: unstimulated peripheral blood-derived CD8 T cells displayed peptide-specific IFN-gamma release ex vivo while CD8 T cell lines and clones exhibited HLA-A68.02-restricted cytolytic activity and recognized endogenously processed antigen. The frequency of CD8 CTL specific for this single M. tuberculosis epitope, 1/2500 peripheral blood lymphocytes, was equivalent to the combined frequency of all IFN-gamma-secreting purified protein derivative-reactive T cells ex vivo. This highly focused CTL response was maintained in an asymptomatic contact over 2 years and is the most potent antigen-specific antimycobacterial CD8 CTL response hitherto described. Thus, human M. tuberculosis-specific CD8 CTL are not necessarily associated with active disease per se. Rather, our results are consistent with a protective role for these ESAT-6-specific CD8 T cells in the long-term control of M. tuberculosis in vivo in humans.
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89
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Ansell J, Hu JT, Gilbert SC, Hamilton KA, Hill AV, Lindsay SW. Improved method for distinguishing the human source of mosquito blood meals between close family members. Trans R Soc Trop Med Hyg 2000; 94:572-4. [PMID: 11132392 DOI: 10.1016/s0035-9203(00)90092-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
We have developed a simple and relatively cheap method to distinguish the origin of mosquito blood meals between close family members, effective for both laboratory and field samples. Each blood meal was squashed on to filter paper and eluted overnight with 0.5 mL phosphate-buffered saline. Deoxyribonucleic acid (DNA) was extracted using a chemical matrix (Insta-gene) which bound to everything from the blood meal except DNA, which remained in the supernatant. Following extractions, reference DNA samples taken directly from finger-prick blood of human subjects and those from blood meals of unknown origin were amplified with human microsatellite markers using a thermal cycler. Polymerase chain reaction products were then run on an ABI gel (Automated Biosystems) to obtain a genotype for each sample. The DNA from each mosquito blood meal was then matched to an individual host. With laboratory samples, human DNA which had been extracted from mosquito blood meals up to 12 h after feeding could be used. One important application of this method will be to identify which members of a community are most at risk from vector-borne diseases. It also has numerous potential applications in studies of insect biting behaviour in both human and veterinary science.
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90
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Abstract
Vaccines against a variety of infectious diseases represent one of the great triumphs of medicine. The immune correlates of protection induced by most current vaccines seem to be mediated by long-lived humoral immune responses. By contrast, there are no currently available vaccines that are uniformly effective for diseases such as HIV, malaria and tuberculosis, in which the cellular immune response might be crucial in mediating protection. Here we examine the mechanisms by which long-lived cellular immune responses are generated and maintained in vivo. We then discuss current approaches for vaccination against diseases in which cellular immune responses are important for protection.
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91
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Abstract
As global malaria mortality increases the urgency for vaccine development, analysis of immune responses in naturally exposed populations is providing clues to the nature of protective immunity. Recently, sophisticated immune evasion strategies adopted by the parasite have been analysed at the molecular level. More immunogenic vaccination strategies have been identified, providing renewed optimism that effective malaria control through vaccination should be feasible.
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92
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Bellamy R, Beyers N, McAdam KP, Ruwende C, Gie R, Samaai P, Bester D, Meyer M, Corrah T, Collin M, Camidge DR, Wilkinson D, Hoal-Van Helden E, Whittle HC, Amos W, van Helden P, Hill AV. Genetic susceptibility to tuberculosis in Africans: a genome-wide scan. Proc Natl Acad Sci U S A 2000; 97:8005-9. [PMID: 10859364 PMCID: PMC16660 DOI: 10.1073/pnas.140201897] [Citation(s) in RCA: 208] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Human genetic variation is an important determinant of the outcome of infection with Mycobacterium tuberculosis. We have conducted a two-stage genome-wide linkage study to search for regions of the human genome containing tuberculosis-susceptibility genes. This approach uses sibpair families that contain two full siblings who have both been affected by clinical tuberculosis. For any chromosomal region containing a major tuberculosis-susceptibility gene, affected sibpairs inherit the same parental alleles more often than expected by chance. In the first round of the screen, 299 highly informative genetic markers, spanning the entire human genome, were typed in 92 sibpairs from The Gambia and South Africa. Seven chromosomal regions that showed provisional evidence of coinheritance with clinical tuberculosis were identified. To identify whether any of these regions contained a potential tuberculosis-susceptibility gene, 22 markers from these regions were genotyped in a second set of 81 sibpairs from the same countries. Markers on chromosomes 15q and Xq showed suggestive evidence of linkage (lod = 2.00 and 1.77, respectively) to tuberculosis. The potential identification of susceptibility loci on both chromosomes 15q and Xq was supported by an independent analysis designated common ancestry using microsatellite mapping. These results indicate that genome-wide linkage analysis can contribute to the mapping and identification of major genes for multifactorial infectious diseases of humans. An X chromosome susceptibility gene may contribute to the excess of males with tuberculosis observed in many different populations.
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93
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Cervino AC, Hill AV. Comparison of tests for association and linkage in incomplete families. Am J Hum Genet 2000; 67:120-32. [PMID: 10841813 PMCID: PMC1287070 DOI: 10.1086/302992] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/1998] [Accepted: 05/04/2000] [Indexed: 11/03/2022] Open
Abstract
To analyze incomplete families, the following statistical tests can be used: LRAT-a simple likelihood-based association test, TRANSMIT, SIBASSOC/STDT, and RCTDT. We compared these four tests, for the diallelic case, on simulated data sets. The comparisons focused on the power to detect linkage and association when different familial structures, resistance to population stratification, resistance to misclassification of the disease status of the healthy sib, and the effect of nonpaternity were considered. The simulations lead to the following conclusions. The type I errors of TRANSMIT, SIBASSOC/STDT, and RCTDT were not affected by population stratification. LRAT showed bias under strong population stratification. High nonpaternity rates can lead to inflated type I errors, highlighting the importance of identification of half sibs. Under different homogeneous models, the power of TRANSMIT was very similar to that of LRAT, and, similarly, no difference in power was observed between SIBASSOC/STDT and RCTDT. Under various recessive and additive models, TRANSMIT was slightly more powerful than SIBASSOC/STDT when monoparental families with one affected and one unaffected sib were analyzed. Under various dominant models, SIBASSOC/STDT was slightly more powerful than TRANSMIT. Misclassification of the disease status of healthy sibs, as well as the discarding of incomplete families, resulted in a consistent loss of power.
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94
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Aitman TJ, Cooper LD, Norsworthy PJ, Wahid FN, Gray JK, Curtis BR, McKeigue PM, Kwiatkowski D, Greenwood BM, Snow RW, Hill AV, Scott J. Malaria susceptibility and CD36 mutation. Nature 2000; 405:1015-6. [PMID: 10890433 DOI: 10.1038/35016636] [Citation(s) in RCA: 188] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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95
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Anderson RP, Degano P, Godkin AJ, Jewell DP, Hill AV. In vivo antigen challenge in celiac disease identifies a single transglutaminase-modified peptide as the dominant A-gliadin T-cell epitope. Nat Med 2000; 6:337-42. [PMID: 10700238 DOI: 10.1038/73200] [Citation(s) in RCA: 423] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Celiac disease (CD) is an increasingly diagnosed enteropathy (prevalence, 1:200-1:300) that is induced by dietary exposure to wheat gliadins (as well as related proteins in rye and barley) and is strongly associated with HLA-DQ2 (alpha1*0501, beta1*0201), which is present in over 90% of CD patients. Because a variety of gliadin peptides have been identified as epitopes for gliadin-specific T-cell clones and as bioactive sequences in feeding studies and in ex vivo CD intestinal biopsy challenge, it has been unclear whether a 'dominant' T-cell epitope is associated with CD. Here, we used fresh peripheral blood lymphocytes from individual subjects undergoing short-term antigen challenge and tissue transglutaminase-treated, overlapping synthetic peptides spanning A-gliadin to demonstrate a transient, disease-specific, DQ2-restricted, CD4 T-cell response to a single dominant epitope. Optimal gamma interferon release in an ELISPOT assay was elicited by a 17-amino-acid peptide corresponding to the partially deamidated peptide of A-gliadin amino acids 57-73 (Q65E). Consistent with earlier reports indicating that host tissue transglutaminase modification of gliadin enhances gliadin-specific CD T-cell responses, tissue transglutaminase specifically deamidated Q65 in the peptide of A-gliadin amino acids 56-75. Discovery of this dominant epitope may allow development of antigen-specific immunotherapy for CD.
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96
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Ali S, Niang MA, N'doye I, Critchlow CW, Hawes SE, Hill AV, Kiviat NB. Secretor polymorphism and human immunodeficiency virus infection in Senegalese women. J Infect Dis 2000; 181:737-9. [PMID: 10669366 DOI: 10.1086/315234] [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: 11/03/2022] Open
Abstract
The FUT2 gene encodes the enzyme alpha (1,2) fucosyltransferase, which determines expression of blood-group antigens on mucosal epithelial cell surfaces and in secretions. Homozygotes for a specific stop mutation in FUT2 (nonsecretors) cannot produce this enzyme and thus are unable to express blood group antigens. Nonsecretor status is associated with a decreased risk of several respiratory viral infections. By use of molecular genotyping, 2 populations of Senegalese women were examined for polymorphisms of the FUT2 gene. Among Senegalese commercial sex workers, absence of FUT2 (nonsecretor genotype) was associated with reduced risk of human immunodeficiency virus (HIV) type 1 infection (odds ratio [OR] adjusted for cervical and vaginal infection, 0.18; 95% confidence interval [CI], 0.04-0.90) and HIV-2 infection (adjusted OR, 0.43; 95% CI, 0.13-1.39), although the latter was not statistically significant. Modification of cell surface carbohydrates at mucosal surfaces determined by the FUT2 gene may underlie the protective association against heterosexual HIV infection.
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97
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Aidoo M, Lalvani A, Gilbert SC, Hu JT, Daubersies P, Hurt N, Whittle HC, Druihle P, Hill AV. Cytotoxic T-lymphocyte epitopes for HLA-B53 and other HLA types in the malaria vaccine candidate liver-stage antigen 3. Infect Immun 2000; 68:227-32. [PMID: 10603392 PMCID: PMC97125 DOI: 10.1128/iai.68.1.227-232.2000] [Citation(s) in RCA: 39] [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
The development of an effective preerythrocytic vaccine against Plasmodium falciparum malaria is likely to require inclusion of components from several preerythrocytic antigens. The association of HLA-B53 with resistance to severe malaria in West Africa provided evidence that HLA class I-restricted CD8(+) T-cell responses play a role in protective immunity in African children, supporting data from rodent models of malaria. Previously, a single epitope from liver-stage-specific antigen 1 (LSA-1) has been shown to be recognized by HLA-B53-specific cytotoxic T lymphocytes (CTL), but HLA-B53 epitopes were not found in four other antigens. In this study we measured CTL responses to peptides from the recently sequenced antigen liver-stage antigen 3 (LSA-3) and identified in it a new epitope restricted by HLA-B53. Several CTL epitopes restricted by other class I types were also identified within LSA-3 in studies in The Gambia and Tanzania. CTL were also identified to an additional P. falciparum antigen, exported protein 1 (Exp-1), the homologue of which is a protective antigen in a rodent model of malaria. These findings emphasize the diversity of P. falciparum antigens recognized by CD8(+) T cells in humans and support the inclusion of components from several antigens in new CTL-inducing vaccines against malaria.
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98
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Dégano P, Schneider J, Hannan CM, Gilbert SC, Hill AV. Gene gun intradermal DNA immunization followed by boosting with modified vaccinia virus Ankara: enhanced CD8+ T cell immunogenicity and protective efficacy in the influenza and malaria models. Vaccine 1999; 18:623-32. [PMID: 10547421 DOI: 10.1016/s0264-410x(99)00278-9] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
In influenza and malaria, CD8+ T cells play an important role in protective immunity in mice. An immunization strategy consisting of DNA priming followed by boosting with recombinant modified vaccinia virus Ankara (MVA) induces complete protection, associated with high levels of CD8+ T cells, against Plasmodium berghei sporozoite challenge in mice. Intradermal delivery of DNA with a gene gun requires smaller amounts of DNA than intramuscular injection, in order to induce similar levels of immune responses. The present study compares both routes for the induction of specific CD8+ T cell responses and protection using different prime-boost immunization regimes in the influenza and the malaria models. In the DNA/MVA regime, equally high CD8+ T cell responses and levels of protection are achieved using ten times less DNA when delivered with a gene gun compared to intramuscular injection.
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MESH Headings
- Animals
- Biolistics
- CD8-Positive T-Lymphocytes/immunology
- DNA, Protozoan/administration & dosage
- DNA, Protozoan/genetics
- DNA, Viral/administration & dosage
- DNA, Viral/genetics
- Female
- Immunization, Secondary
- Influenza Vaccines/administration & dosage
- Influenza Vaccines/genetics
- Influenza Vaccines/immunology
- Malaria/immunology
- Malaria/prevention & control
- Malaria Vaccines/administration & dosage
- Malaria Vaccines/genetics
- Malaria Vaccines/immunology
- Male
- Mice
- Mice, Inbred BALB C
- Mice, Inbred C57BL
- Orthomyxoviridae Infections/immunology
- Orthomyxoviridae Infections/prevention & control
- Plasmodium berghei/immunology
- Vaccines, Attenuated/administration & dosage
- Vaccines, Attenuated/genetics
- Vaccines, Attenuated/immunology
- Vaccines, DNA/administration & dosage
- Vaccines, DNA/genetics
- Vaccines, DNA/immunology
- Vaccinia virus/genetics
- Vaccinia virus/immunology
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99
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Lalvani A, Moris P, Voss G, Pathan AA, Kester KE, Brookes R, Lee E, Koutsoukos M, Plebanski M, Delchambre M, Flanagan KL, Carton C, Slaoui M, Van Hoecke C, Ballou WR, Hill AV, Cohen J. Potent induction of focused Th1-type cellular and humoral immune responses by RTS,S/SBAS2, a recombinant Plasmodium falciparum malaria vaccine. J Infect Dis 1999; 180:1656-64. [PMID: 10515829 DOI: 10.1086/315074] [Citation(s) in RCA: 128] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
The RTS,S/SBAS2 vaccine confers sterile protection against Plasmodium falciparum sporozoite challenge. The mechanisms underlying this are of great interest, yet little is known about the immune effector mechanisms induced by this vaccine. The immune responses induced by RTS,S/SBAS2 were characterized in 10 malaria-naive volunteers. Several epitopes in the circumsporozoite protein (CSP) were identified as targets of cultured interferon (IFN)-gamma-secreting CD4+ T cells. RTS,S-specific IFN-gamma-secreting effector T cells were induced in 8 subjects; this ex vivo response mapped to a single peptide in Th2R. CSP-specific CD8+ cytotoxic T lymphocytes were not detected. RTS, S-specific IFN-gamma production was universal, whereas interleukin-4 and -5 production was rare. RTS,S-specific lymphoproliferative responses and antibodies to CSP were strongly induced in all volunteers. Responses waned with time but were boostable. Thus, RTS, S/SBAS2 is a potent inducer of Th1-type cellular and humoral immunity. These results highlight possible immune mechanisms of protection and have important implications for vaccine design in general.
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100
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Schneider J, Gilbert SC, Hannan CM, Dégano P, Prieur E, Sheu EG, Plebanski M, Hill AV. Induction of CD8+ T cells using heterologous prime-boost immunisation strategies. Immunol Rev 1999; 170:29-38. [PMID: 10566139 DOI: 10.1111/j.1600-065x.1999.tb01326.x] [Citation(s) in RCA: 154] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
One of the current challenges in vaccine design is the development of antigen delivery systems or vaccination strategies that induce high protective levels of CD8+ T cells. These cells are crucial for protection against certain tumours and intracellular pathogens such as the liver-stage parasite of malaria. A liver-stage malaria vaccine should therefore include CD8+ T-cell-inducing components. This review provides an overview of prime-boost immunisation strategies that result in protective CD8+ T-cell responses against malaria with an emphasis on work from our laboratory. Possible mechanisms explaining why heterologous prime-boost strategies, in particular boosting with replication-impaired recombinant poxviruses, are so effective are discussed.
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