CD8A and infection: To identify αβTCRs directed at two immunodominant but differentially arrayed influenza A virus (IAV)-specific epitopes, nucleoprotein (NP)366–374/Db and polymerase acidic (PA)224–233/Db, tetramers were used to concurrently isolate CD8 T lymphocytes from lung parenchyma 5 days postsecondary infection using singlecell sorting, reverse transcription polymerase chain reaction (RT-PCR) molecular cloning, and DNA sequencing (fig.