Identification of a protein encoded in the EB-viral open reading frame BMRF2

Using monospecific rabbit sera against a peptide derived from a potential antigenic region of the Epstein-Barr viral amino acid sequence encoded in the open reading frame BMRF2 we could identify a protein-complex of 53/55 kDa in chemically induced B95-8, P3HR1 and Raji cell lines. This protein could be shown to be membrane-associated, as predicted by previous computer analysis of the secondary structure and hydrophilicity pattern, and may be a member of EBV-induced membrane proteins in lytically infected cells

The mitogenic activity of human T-cell leukemia virus type I is T-cell associated and requires the CD2/LFA-3 activation pathway.

The presence of a high number of activated T cells in the bloodstream and spontaneous proliferation of peripheral blood mononuclear cells in vitro are striking characteristics of human T-cell leukemia virus type I (HTLV-I) infection. The HTLV-I regulatory protein Tax and the envelope protein gp46 have been implicated in mediating the activation process. In this study, HTLV-I-producing cell lines and purified virus from the cell lines were examined for the ability to activate peripheral blood lymphocytes (PBLs) and Jurkat cells. Antisera and monoclonal antibodies against several cellular adhesion proteins involved in T-cell activation and against viral proteins were used to identify which molecules may be participating in the activation process. First, neither virus from a T-cell line, MT2, nor virus produced from the human osteosarcoma cell line HOS/PL was able to induce PBLs to proliferate. In contrast, both fixed and irradiated HTLV-I-producing T-cell lines induced proliferation of PBLs; HOS/PL cells did not activate PBLs. Second, HTLV-I-positive T-cell lines were capable of activating interleukin-2 mRNA expression in Jurkat cells. Induction of interleukin-2 expression was inhibited by anti-CD2 and anti-lymphocyte function-associated antigen 3 (LFA-3) monoclonal antibodies but not anti-human leukocyte antigen-DR, anti-CD4, anti-LFA-1, or anti-intercellular adhesion molecule 1. Similar results were obtained with PBLs as the responder cells. Furthermore, monoclonal antibodies and antisera against various regions of the HTLV-I envelope proteins gp46 and gp21 as well as p40tax did not block activation. These data indicate that HTLV-I viral particles are not intrinsically mitogenic and that infection of target T cells is not necessary for activation. Instead, the mitogenic activity is restricted to virus-producing T cells, requires cell-to-cell contact, and may be mediated through the LFA-3/CD2 activation pathway

Intranasal immunization with CTL epitope peptides from HIV-1 or ovalbumin and the mucosal adjuvant cholera toxin induces peptide-specific CTLs and protection against tumor development in vivo

To evaluate the ability of mucosal immunization protocols using peptide immunogens to induce CTL responses, BALB/c and C57BL/6 mice were immunized intranasally (i.n.) with peptides corresponding to a known CTL epitope in HIV-1 glycoprotein 120 or OVA, respectively, and the mucosal adjuvant cholera toxin (CT). Intranasal immunization of BALB/c mice with a 10- or 15-amino acid peptide corresponding to a CTL determinant in HIV-1 glycoprotein 120 and CT induced peptide-specific CTLs in spleen cells that persisted through 35 days after the last immunization. Intranasal immunization of C57BL/6 mice with the octameric OVA peptide and CT produced similar results with detectable peptide-specific CTL in both the cervical lymph node and spleen. To test whether CTL induced by i.n. immunization with OVA peptide and CT were functional in vivo, groups of C57BL/6 mice were injected with E.G7-OVA tumor cells that express the OVA protein and monitored for tumor growth. Animals immunized i.n. with OVA and CT were protected against tumor development as efficiently as animals immunized by the potent CTL induction protocol of i.v. injection with OVA-pulsed dendritic cells. Intranasal immunization with peptides corresponding to known CTL epitopes and CT provides a noninvasive route of immunization for the induction of CTL responses in vivo