The Parallel Presentation of Two Functional CTL Epitopes Derived from the O and Asia 1 Serotypes of Foot-and-Mouth Disease Virus and Swine SLA-2*HB01: Implications for Universal Vaccine Development.

Foot-and-mouth disease virus (FMDV) poses a significant threat to the livestock industry. Through their recognition of the conserved epitopes presented by the swine leukocyte antigen (SLA), T cells play a pivotal role in the antiviral immunity of pigs. Herein, based on the peptide binding motif of SLA-2*HB01, from an original SLA-2 allele, a series of functional T-cell epitopes derived from the dominant antigen VP1 of FMDV with high binding capacity to SLA-2 were identified. Two parallel peptides, Hu64 and As64, from the O and Asia I serotypes, respectively, were both crystallized with SLA-2*HB01. Compared to SLA-1 and SLA-3, the SLA-2 structures showed the flexibility of residues in the P4, P6, and P8 positions and in their potential interface with TCR. Notably, the peptides Hu64 and As64 adopted quite similar overall conformation when bound to SLA-2*HB01. Hu64 has two different conformations, a more stable 'chair' conformation and an unstable 'boat' conformation observed in the two molecules of one asymmetric unit, whereas only a single 'chair' conformation was observed for As64. Both Hu64 and As64 could induce similar dominant T-cell activities. Our interdisciplinary study establishes a basis for the in-depth interpretation of the peptide presentation of SLA-I, which can be used toward the development of universal vaccines.

Expression, purification, crystallization and preliminary X-ray diffraction analysis of swine leukocyte antigen 2 complexed with a CTL epitope AS64 derived from Asia1 serotype of foot-and-mouth disease virus.

BACKGROUND: Currently, the structural characteristics of the swine major histocompatibility complex (MHC) class I molecule, also named swine leukocyte antigen class I (SLA-I) molecule need to be further clarified. RESULTS: A complex of SLA-I constituted by an SLA-2*HB01 molecule with swine ß2-microglobulin and a cytotoxic T lymphocyte (CTL) epitope FMDV-AS64 (ALLRSATYY) derived from VP1 protein (residues 64-72) of Asia 1 serotype of foot-and-mouth disease virus (FMDV) was expressed, refolded, purified and crystallized. By preliminary X-ray diffraction analysis, it was shown that the diffraction resolution of the crystal was 2.4 Å and the space group belonged to P212121 with unit cell parameters a = 48.37, b = 97.75, c = 166.163 Å. CONCLUSION: This research will be in favor of illuminating the structural characteristics of an SLA-2 molecule associated with a CTL epitope derived from Asia1 serotype of FMDV.

Purification, crystallization and preliminary X-ray crystallographic studies of swine MHC class I complexed with an FMDV CTL epitope Hu64.

Up to now, no crystal structure of swine leukocyte antigen 2 (SLA-2) molecules was reported. In order to elucidate the structure of SLA-2 and to study the cytotoxic T lymphocyte (CTL) epitopes derived from foot-and-mouth disease virus (FMDV), a complex of swine major histocompatibility complex (MHC) class I molecule (SLA-2 haplotype, Hebao allele) with swine ß2-microglobulin and the CTL epitope FMDV-Hu64 (ALLRTATYY) derived from O serotype of FMDV VP1 protein (residues 64-72) was refolded and crystallized. The crystal, which belonged to space group P212121, diffracted to 2.5 Šresolution and had unit cell parameters a = 48.37, b = 97.75, c = 166.163 Å. These results will help to determine the first structure of a SLA-2 molecule in the context of an FMDV CTL epitope.

Identification of two novel foot-and-mouth disease virus cytotoxic T lymphocyte epitopes that can bind six SLA-I proteins.

Currently available vaccines from inactivated foot-and-mouth disease virus (FMDV) only protect animals by inducing neutralizing antibodies. A vaccine that contains cytotoxic T lymphocytes (CTL) epitopes to induce strong CTL responses might protect animals more effectively. Herein, we used swine leukocyte antigen class I (SLAI) proteins derived from six different strains of domestic pigs to screen and identify shared FMDV CTL epitopes. Four potential FMDV CTL epitopes (Q01, Q02, AS3, and QA4) were confirmed by mass spectrometry. We also determined the antigenicity of these epitopes to elicit cell-mediated immunoresponse by the ELISPOT and CTL assays. Among the four peptides, Q01 and QA4 were found to bind all six SLA-I proteins with strong affinity and elicit significant activity of CTL (P < 0.01). We conclude that Q01 and QA4 peptides are novel shared epitopes that can be recognized by all six SLA-I molecules on representative CTLs.