Immediate-Early Transactivator Rta of Epstein-Barr Virus (EBV) Shows Multiple Epitopes Recognized by EBV-Specific Cytotoxic T Lymphocytes

Abstract

We analyzed the immediate-early transactivator Rta of Epstein-Barr virus (EBV) for its role as a target for specific cytotoxic T lymphocytes (CTL). Panels of overlapping peptides covering the entire amino acid sequence of Rta were synthesized and used to induce and analyze specific CTL responses in EBV-positive donors. Using peptide-pulsed target cells, we found nine different CTL epitopes that are distributed over the entire protein sequence. One epitope restricted by HLA-A24 could be mapped to the decameric sequence DYCNVLNKEF between amino acid positions 28 and 37 of the Rta protein. A second epitope could be assigned to the same region of Rta (residues 25 to 39) and was shown to be restricted by HLA-B18. Another, minimal epitope could be mapped to the nonameric sequence ATIGTAMYK between amino acid positions 134 and 142; this peptide was restricted by HLA-A11. Another four epitopes were proven to be restricted by HLA-A2, -A3, -B61, and -Cw4 and were located between Rta residues 225 and 239, 145 and 159, 529 and 543, and 393 and 407, respectively. For two other epitopes, only the location within the Rta protein is known so far (residues 121 to 135 and 441 to 455); their exact HLA restriction patterns have not yet been identified. Using target cells infected with recombinant vaccinia virus containing the gene for Rta, we showed that six of eight Rta-specific CTL lines recognized the corresponding peptides also after endogenous processing. These data suggest that Rta comprises an important target for EBV-specific cellular cytotoxicity. Together with recent findings of other immediate-early and early proteins also acting as CTL targets, they reveal the role of proteins of the lytic cycle in the immune recognition of EBV-infected cells.

Vaccine strategies against Epstein‐Barr virus‐associated diseases: lessons from studies on cytotoxic T‐cell‐mediated immune regulation

“…Perhaps the best evidence, iu fact, came from studies by Bogedain and colleagues (33) who demonstrated for the first time that CTLs from HLA-B8-positive healthy virus carriers display strong reactivity towards the immediate eariy BZLFl protein. Subsequent studies using iimiting dilution anaiysis (LDA) showed that BZLE1-reactive CTLs in healthy virus carriers are at frequencies comparable to those of CTLs reactive with EBV latent antigens (3 7), These fmdings have also been confirmed by Steven et al (38) and Pepperi et al, (34) who, in addition, showed that specific CTL responses are also directed against tiie immediate early antigen Rta, encoded by the open reading frame BRLFl, and early antigens encoded hy BMLEl, BMREl and BALF2. Pepperi and coiieagues proposed that CTL reactivity towards iytic antigens may represent a second line of defence against the virus by controiiing its repiication in vivo (34).…”

“…Subsequent studies using iimiting dilution anaiysis (LDA) showed that BZLE1-reactive CTLs in healthy virus carriers are at frequencies comparable to those of CTLs reactive with EBV latent antigens (3 7), These fmdings have also been confirmed by Steven et al (38) and Pepperi et al, (34) who, in addition, showed that specific CTL responses are also directed against tiie immediate early antigen Rta, encoded by the open reading frame BRLFl, and early antigens encoded hy BMLEl, BMREl and BALF2. Pepperi and coiieagues proposed that CTL reactivity towards iytic antigens may represent a second line of defence against the virus by controiiing its repiication in vivo (34). Indeed, a weakened immune response to Iytic antigens couid explain the recurrence of virus repiication and enhanced viral shedding seen in immunocompromised patients.…”

“…This is mainiy due to the fact that there is no known in vitro-grown ceii that can serve as tlie target for a fully permissive EBV infection. By using a modified approach based on synthetic peptides and recombinant vaccinia, a number of groups have now identified CTL responses directed against EBV immediate eariy, early and late Iytic proteins (33)(34)(35)(36). Perhaps the best evidence, iu fact, came from studies by Bogedain and colleagues (33) who demonstrated for the first time that CTLs from HLA-B8-positive healthy virus carriers display strong reactivity towards the immediate eariy BZLFl protein.…”

Sequencing of DC-SIGN promoter indicates an association between promoter variation and risk of nasopharyngeal carcinoma in cantonese

“…Epstein-Barr virus (EBV) is considered a major risk factor for NPC, and there is a dose-response relationship between EBV antibodies and NPC risk [6,7]. EBV is present in over 90% of the world population [8], most often as a form of in vivo latency in healthy carriers with low copies of episomal virus maintained in resting memory B cells [9][10][11].…”

Cellular and Humoral Immunity following Snow Mountain Virus Challenge

“…A Th1-favored response is primarily characterized by secretion of gamma interferon (IFN-␥) by CD4 ϩ cells, resulting in macrophage activation, B-cell differentiation to IgG1 synthesis, and support for cytotoxic T lymphocytes (CTLs). CTLs are important in the control of human immunodeficiency virus (HIV) (4), Epstein-Barr virus (42), influenza virus (26), lymphocytic choriomeningitis virus (52), and numerous other viruses. To date, cellular immunity has not been studied following norovirus infection, but we expect effector T cells to play a fundamental role in viral clearance and immunity.…”