Heterogeneity of the Vβchain of polyoma virus-specific Vβ6+ CTL clones

Our previous studies [Lukacher et ai, J. Exp. Med.181:1683-1692 (1995)] indicate that susceptibility to tumors induced by polyoma virus in tf-2 mice is conferred by deletion of Vβ6⁺ CD8⁺ CTL by an endogenous superantigen encoded by the Mtv-7 provirus. We have isolated T cell clones from polyomainfected H- 2fc Mtv -7 (polyoma tumor-resistant) mice. These CD8⁺ clones possess polyoma-specific cytotoxic activity, are restricted by the Dk molecule, and express the Vβ6-TCR. Here, we ask whether regions of Vβ in addition lo the germline-encoded V06-segment are conserved by these CTL clones. RTPCR was performed on RNA isolated from CTL clones with a Vβ6-specific sense primer and a consensus C3 antisense primer. For each CTL clone, the products from three independent PCR reactions were cloned and sequenced in both directions. We have found usage of different Dβ and J3 segments, very few N-nucleotide additions and similar CDR3 loop lengths by the Vβ6⁺ CTL clones. Experiments are in progress to sequence the Vβ chains of additional Vβ6⁺ CTL clones, as well as their Va chains.