Cloning and characterization of antiviral cytotoxic T lymphocytes in channel catfish, Ictalurus punctatus.

To determine the role of piscine anti-viral cytotoxic cells, we analyzed the response of channel catfish to Ictalurid herpesvirus 1 , commonly designated channel catfish virus (CCV). Peripheral blood leukocytes (PBL) from catfish immunized with MHC-matched, CCV-infected G14D cells (G14D-CCV) showed marked lysis of G14D-CCV but little to no lysis of uninfected allogenic (3B11) or syngeneic (G14D) cells. Expansion of effectors by in vitro culture in the presence of irradiated G14D-CCV cells generated cultures with enhanced cytotoxicity and often broader target range. Cytotoxic effectors expressed rearranged TCR genes, perforin, granzyme, and IFN-γ. Four clonal cytotoxic lines were developed and unique TCR gene rearrangements including γδ were detected. Furthermore, catfish CTL clones were either CD4+/CD8- or CD4-/CD8-. Two CTL lines showed markedly enhanced killing of G14D-CCV targets, while the other two lines displayed a broader target range. Collectively, catfish virus-specific CTL display unique features that illustrate the diversity of the ectothermic vertebrate immune response. • Teleost anti-viral cytotoxic T cells are heterogeneous. • Four catfish anti-viral clonal cytotoxic T cell lines were established. • Two cell lines preferentially lysed channel catfish virus-infected syngeneic targets. • One clonal γδ T cell line exhibits broad target cell recognition. • None of these T cell lines expressed CD8, however three expressed CD4-like molecules. [ABSTRACT FROM AUTHOR]