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Respiratory syncytial virus nucleoprotein-specific cytotoxic T-cell epitopes in a South African population of diverse HLA types are conserved in circulating field strains.

ABSTRACT: This study identifies memory cytotoxic T lymphocyte (CTL) epitopes to respiratory syncytial virus (RSV) in healthy South African adults and demonstrates the conservation of those epitopes in circulating field strains of RSV in South Africa. Thirty-seven healthy adults from a population with diverse HLA backgrounds were screened by gamma interferon (IFN-gamma) enzyme-linked immunospot for memory CTL activity in response to overlapping peptides representing the complete nucleoprotein (N) of RSV. Responses of more than 40 spot-forming cells/million cells were detectable in 21 individuals. The significant responses were further characterized, and 14-mer peptides were identified that induced cytolytic activity. Fine mapping of peptides with the highest cytolytic activity identified an HLA-B(*)08-restricted RSV-specific CTL epitope. The extended 14-mer peptide containing this epitope also induced lysis in the context of A(*)02-restricted target cells in some individuals. These HLA types are common in the target population; thus, the epitope is useful for studies of CTL responses to RSV in humans. The epitope was detected in healthy adults, reflecting the response generated in the course of previous natural RSV infection. We obtained a large panel of naturally occurring isolates of RSV to determine whether there was evidence of escape from CTL activity in circulating strains. We found that this epitope and a previously identified B(*)07-restricted N protein epitope were conserved in RSV field strains representing the diversity of circulating genotypes. This work suggests that escape from CTL activity is not common for this acute respiratory infection.

SUBMITTER: Venter M

PROVIDER: S-EPMC164818 | biostudies-literature | 2003 Jul

REPOSITORIES: biostudies-literature

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Respiratory syncytial virus nucleoprotein-specific cytotoxic T-cell epitopes in a South African population of diverse HLA types are conserved in circulating field strains.

Venter Marietjie M Rock Michael M Puren Adrian J AJ Tiemessen Caroline T CT Crowe James E JE

Journal of virology 20030701 13

This study identifies memory cytotoxic T lymphocyte (CTL) epitopes to respiratory syncytial virus (RSV) in healthy South African adults and demonstrates the conservation of those epitopes in circulating field strains of RSV in South Africa. Thirty-seven healthy adults from a population with diverse HLA backgrounds were screened by gamma interferon (IFN-gamma) enzyme-linked immunospot for memory CTL activity in response to overlapping peptides representing the complete nucleoprotein (N) of RSV. R ...[more]

PMID: 12805430

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Project description:Background and aimAfrican swine fever (ASF) is a viral disease of pigs caused by ASF virus (ASFV). High mortality and the lack of available treatments have severely impacted the swine industry resulting in huge global economic losses. In response to the dire necessity for vaccines, this study aims to identify highly conserved cytotoxic T-cell epitopes in ASFV structural proteins pp220, pp62, p72, p30, and CD2v through immunoinformatics approach.Materials and methodsThe amino acid sequences of the structural proteins were retrieved from the National Center for Biotechnology Information protein database. The sequences were evaluated in CD-HIT Suite wherein resulting representative sequences were aligned in Clustal Omega. Highly conserved sequences were identified in the Protein Variability Server which were used as reference sequences for the cytotoxic T-cell epitope mapping. Epitopes were predicted using the tools in Immune Epitope Database. Peptides which bind to the swine major histocompatibility complex with IC50 binding scores >500 nM were filtered out. Epitopes which are classified to be potentially toxic and cross-reactive with the swine proteome sequences were all excluded from the study. The epitopes were docked with the swine leukocyte antigen-1*0401 (SLA-1*0401) wherein the binding affinity, the binding energy, and the root-mean-square deviation (RMSD) per residue of epitope-SLA complexes formed were determined and compared with the influenza epitope as positive control.ResultsA total of 112 highly conserved fragments with Shannon variability index ≤0.1 were identified. These include 66, 12, 26, 6, and 2 highly conserved fragments from ASFV proteins pp220, pp62, p72, p30, and CD2v, respectively. From these reference sequences, 35 nonameric peptides were selected for the list of candidate cytotoxic T-cell epitopes. These include 26 epitopes for pp220, 7 for pp62, 6 for p72, and one each for p30 and CD2v. Bioinformatics analysis classified the peptides as non-toxic. Further evaluations of epitopes showed that these are less likely to cross-react with the domestic swine proteome sequences. This study identified candidate epitopes from pp220 (IADAINQEF, FLNKSTQAY, QIYKTLLEY, and SLYPTQFDY), and pp62 (GTDLYQSAM, FINSTDFLY, and STDFLYTAI) which can bind to at least two widely distributed SLAs in pig populations. The immunogenicity of candidate peptides RSNPGSFYW, DFDPLVTFY, AIPSVSIPF, and VVFHAGSLY was validated by the acceptable binding affinities, binding energies, and RMSD of the peptide-SLA complexes formed. Results were also comparable with the crystal structure of an SLA-epitope complex in the database.ConclusionThis is the first study to identify highly conserved cytotoxic T-cell epitopes in the structural proteins of ASFV. Overall, the results of in silico evaluations showed that the identified highly conserved cytotoxic T-cell epitopes may be used as part of future vaccine formulations against ASFV infection in domesticated pigs. Nonetheless, these findings require in vitro and in vivo validation before application.

Project description:T cells must play the major role in controlling acute human Lassa virus infection, because patients recover from acute Lassa fever in the absence of a measurable neutralizing antibody response. T cells alone seem to protect animals from a lethal Lassa virus challenge, because after experimental vaccination no neutralizing antibodies are detectable. In order to study human T-cell reactivity to single Lassa virus proteins, the nucleoprotein (NP) of Lassa virus, strain Josiah, was cloned, expressed in Escherichia coli, and affinity purified. Peripheral blood mononuclear cells (PBMC) obtained from 8 of 13 healthy, Lassa virus antibody-positive individuals living in the Republic of Guinea, western Africa, were found to proliferate in response to the recombinant protein (proliferation index >/=10). PBMC obtained from one individual with a particularly high proliferative response were used to generate 50 NP-specific T-cell clones (TCC). For six of these the epitopes were mapped with overlapping synthetic peptides derived from the sequence of the NP. These CD4(+) TCC displayed high specific proliferation and produced mainly gamma interferon upon stimulation with NP. Because variation of up to 15% in the amino acid sequences of the structural proteins of naturally occurring Lassa virus variants has been observed, the reactivity of the TCC with peptides derived from the homologous epitopes of the Nigeria strain of Lassa virus and of the eastern Africa arenavirus Mopeia was tested. With the Nigeria strain of Lassa virus the levels of homology were 100% for two of these epitopes and 85% for three of them, whereas homology with the respective Mopeia epitopes ranged from 92 to 69%. Reactivity of the TCC with peptides derived from the variable epitopes of the Nigeria strain and of Mopeia was reduced or completely abolished. This report shows for the first time that seropositive individuals from areas of endemicity have very strong memory CD4(+) T-cell responses against the NP of Lassa virus, which are partly strain specific and partly cross-reactive with other Lassa virus strains. Our findings may have important implications for the strategy of designing recombinant vaccines against this mainly T-cell-controlled human arenavirus infection.

Project description:UnlabelledIdentification and characterization of CD8(+) T cells effectively controlling HIV-1 variants are necessary for the development of AIDS vaccines and for studies of AIDS pathogenesis, although such CD8(+) T cells have been only partially identified. In this study, we sought to identify CD8(+) T cells controlling HIV-1 variants in 401 Japanese individuals chronically infected with HIV-1 subtype B, in which protective alleles HLA-B*57 and HLA-B*27 are very rare, by using comprehensive and exhaustive methods. We identified 13 epitope-specific CD8(+) T cells controlling HIV-1 in Japanese individuals, though 9 of these epitopes were not previously reported. The breadths of the T cell responses to the 13 epitopes were inversely associated with plasma viral load (P = 2.2 × 10(-11)) and positively associated with CD4 count (P = 1.2 × 10(-11)), indicating strong synergistic effects of these T cells on HIV-1 control in vivo. Nine of these epitopes were conserved among HIV-1 subtype B-infected individuals, whereas three out of four nonconserved epitopes were cross-recognized by the specific T cells. These findings indicate that these 12 epitopes are strong candidates for antigens for an AIDS vaccine. The present study highlighted a strategy to identify CD8(+) T cells controlling HIV-1 and demonstrated effective control of HIV-1 by those specific for 12 conserved or cross-reactive epitopes.ImportanceHLA-B*27-restricted and HLA-B*57-restricted cytotoxic T lymphocytes (CTLs) play a key role in controlling HIV-1 in Caucasians and Africans, whereas it is unclear which CTLs control HIV-1 in Asian countries, where HLA-B*57 and HLA-B*27 are very rare. A recent study showed that HLA-B*67:01 and HLA-B*52:01-C*12:02 haplotypes were protective alleles in Japanese individuals, but it is unknown whether CTLs restricted by these alleles control HIV-1. In this study, we identified 13 CTLs controlling HIV-1 in Japan by using comprehensive and exhaustive methods. They included 5 HLA-B*52:01-restricted and 3 HLA-B*67:01-restricted CTLs, suggesting that these CTLs play a predominant role in HIV-1 control. The 13 CTLs showed synergistic effects on HIV-1 control. Twelve out of these 13 epitopes were recognized as conserved or cross-recognized ones. These findings strongly suggest that these 12 epitopes are candidates for antigens for AIDS vaccines.

Dataset Information

Respiratory syncytial virus nucleoprotein-specific cytotoxic T-cell epitopes in a South African population of diverse HLA types are conserved in circulating field strains.

Publications

Respiratory syncytial virus nucleoprotein-specific cytotoxic T-cell epitopes in a South African population of diverse HLA types are conserved in circulating field strains.

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