Resistance to viral infection by intraepithelial lymphocytes in HIV-1 P18-I10-specific T-cell receptor transgenic mice Hideki Kuribayashi, a Ayako Wakabayashi, a Masumi Shimizu, a Hiroshi Kaneko, b Yoshihiko Norose, a Yohko Nakagawa, a Jian Wang, c Yoshihiro Kumagai, a David H. Margulies, c and Hidemi Takahashi a, * a Department of Microbiology and Immunology, Nippon Medical School, Tokyo 113-8602, Japan b Department of Joint Diseases and Rheumatism, Nippon Medical School, Tokyo 113-8602, Japan c Molecular Biology Section, Laboratory of Immunology, NIAID, NIH, Bethesda, MD 20892, USA Received 2 February 2004 Abstract For the analysis of mucosal immunity to HIV-1, we have recently established a line of transgenic (Tg) mice expressing the TCRa and TCRb genes of the murine CTL clone RT1 specific for P18-I10 (RGPGRAFVTI), an immunodominant gp160 envelope-derived epitope of IIIB isolate, restricted by the H-2D d MHC-I molecule. Here we examine those cells bearing specific TCR among the intraepithelial lymphocytes (IELs), with flow cytometric analysis using H-2D d /P18-I10 tetramers. We observed three distinct CD3 þ , tetramer positive populations among the IELs: extra-thymic CD8aa þ , abTCR T-cells; CD8aa þ , cdTCR T-cells; and thymus-de- rived CD8ab þ , abTCR T-cells. Challenge of these Tg mice with P18-I10 encoded by a vaccinia virus vector, either intrarectally (i.r.) or intraperitoneally (i.p.), revealed that the intraepithelial compartment seems to be a major site for prevention of the spread of viral infection. Such immunity appears due to the thymus-derived, CD8ab þ antigen-specific CTLs together with CD8aa þ cd cells, which regulate virus spread. This model system for studying CTL based immunity at mucosal sites should prove helpful in developing rational approaches for HIV control. Ó 2004 Elsevier Inc. All rights reserved. Keywords: HIV-1; Mucosal immunity; Transgenic mice; TCR; CTL; IELs; Tetramer; abTCR; cdTCR; Vaccinia virus vector Viruses replicate intracellularly and virus-encoded components are sampled by cellular machinery that processes proteins into antigenic fragments and presents them on the cell surface in association with class I MHC [1–4]. Molecular complexes of such virus-derived frag- ments associated with class I MHC are recognized by CD8-positive T lymphocytes bearing specific T-cell re- ceptors (TCRs) and stimulate them to become effector cytotoxic T lymphocytes (CTLs) which may control in- tracellular viral replication either by secreting antiviral factors [5] or by eliminating virus-infected cells by in- ducing apoptosis in these targets [6]. Thus, virus-specific CD8 þ CTLs are thought to be critical immune effectors for preventing virus spread in the infected organism. A frequent route of entry into the vertebrate host of many viruses is by invasion through mucosal tissues. In the case of human immunodeficiency virus type-1 (HIV- 1), the majority of primary infections occur at a mucosal site [7]. Indeed, it has recently been shown that pro- ductive simian immunodeficiency virus (SIV) infection in rhesus monkeys takes place at intestinal sites within days of infection, before any changes in systemic pe- ripheral lymphoid tissues can be detected [8]. Because HIV and SIV replicate optimally in activated memory CD4 þ T-cells [9,10], the intestinal mucosal site may be the preferred target for initial infection and replication of HIV. Therefore, CTL involvement in mucosal tissue during the course of HIV infection may play a crucial role in the early stages and is an important focus for study. However, analysis of mucosal CTLs is generally quite difficult in humans, and to date only few studies of SIV have investigated SIV-specific CTLs in mucosal * Corresponding author. Fax: +81-3-3316-1904. E-mail address: htkuhkai@nms.ac.jp (H. Takahashi). 0006-291X/$ - see front matter Ó 2004 Elsevier Inc. All rights reserved. doi:10.1016/j.bbrc.2004.02.058 Biochemical and Biophysical Research Communications 316 (2004) 356–363 BBRC www.elsevier.com/locate/ybbrc