Similarly, to our results with the DbPATCRβ clonotypes, these gB-specific CD8+ T-cell responses in A7 mice were characterized by the same dominant Vβ bias but limited TCRβ repertoire diversity of HSV-derived CTL lines. gB-specific CD8+ T cells expressed the transgene Vα2 product, with no other Vα chains detected by surface staining. Thus, both Kb- and Db-restricted CD8+ T cells can be generated in transgenic A7 mice expressing fixed KbOVA257-specific Vα2 chain, with the limited TCRβ diversity being a result of structural constrains caused by TCR forced to use a single “irrelevant” TCRα-chain. It would be of interest to

further investigate such extreme flexibility in TCRαβ pairing in other systems of viral infection. Further evidence for flexibility in TCRαβ pairing comes from an in vitro study, in

which random pairing of naïve TCRβ and TCRα chains selected from hundreds of FDA-approved Drug Library datasheet TCRα or TCRβ transfectants specific or nonspecific for HIVgp160 showed that one-third of TCRαβ heterodimers retained their specificity 36, confirming a great level of flexibility in TCRαβ pairing. Thus, the breadth of TCRαβ diversity ensures that the fine peptide specificity is available when needed. Even if some of the DbNPCD8+ T cells from the A7 mice are using an alternate TCRα chain, from use of the ICS assay that stimulates all responding CTL irrespective of their particular TCRαβ pairing, the response to DbNP366 in the A7 TCR JQ1 molecular weight transgenic mice is suboptimal, both numerically and in the establishment of the “normal” immunodominance profile following secondary challenge. We have further established that the peptide-induced cytokine profiles are diminished and

that the response overall looks to be of lower avidity. This profile of compromised function is also apparent, though less dramatically, for the DbPA224-specfic T cells. Overall, the present experiments thus provide baselines for the further dissection of “adequate” versus Palmatine “ideal” CD8+ T-cell response and memory, providing insights that will inevitably factor into our thinking as we seek to develop improved CD8+T-cell vaccine and immunotherapy protocols. The B6 and H2b-congenic A7 and A9 mice were bred and housed at the Department of Microbiology and Immunology, University of Melbourne. The TCRα-chain transgenic A7 mice express the Vα2.7 (TCRAV2S7J26) TCR α-chain 18 derived from a KbOVA257-264 specific CTL clone 149.42 37. The A9 mice are transgenic for the Vβ5.2 (TCRBV5S2D2J2S6) 38 from a KbOVA257–264-specific CTL clone B3.1 39. The CDR3α sequence for A7 transgenic mice is SDNYQL, whereas the CDR3β sequence for A9 mice is SRANYEQ. All experiments followed the guidelines of the University of Melbourne Animal Ethics Experimentation Committee. Mice were lightly anaesthetized by inhalation of methoxyflurane and infected i.n. with 1×104 plaque forming units (p.f.u.) of A/HKx31 H3N2 influenza virus (X31) (H3N2, X31) influenza A virus in 30 μL of PBS. Mice used for recall responses were first primed i.p.