ELISPOT cloning of RLakt by B-24 CTL from an RL male 1 cDNA expression library. The first two rounds of screening were large scale assays in 24-well culture plates (10,000 and 1,000 bacterial colonies per pool) and the last three rounds were small scale assays in 96-well culture plates (100 and 10 bacterial colonies per pool and single clone). Refer to the text for details.