DNA prime and Plasmodium yoelii (Py) fresh- or cryopreserved radiation attenuated sporozoite (cryo-RAS) trap leads to substantial parasite liver burden. (A) Experimental design of prime-and-trap liver burden studies. (B) Four hours after trapping with either fresh-RAS, cryo-RAS, or heat-killed sporozoite (HK-spz) mouse livers were excised and processed for real-time reverse transcription polymerase chain reaction (RT-PCR) to measure liver stage parasite burden with 18S pan Plasmodium primers. Data are shown as cycle thresholds (B) for all mice and for absolute 18S rRNA quantification for a subset of the mice where absolute calibrators were used (C). Error bars represent the SD of the mean of N = 15 mice across two experiments (N = 7 mice across two experiments for HK-spz). Data points correspond to individual mice. 95% CI of mean: fresh-RAS 24.1–25.7, cryo-RAS 27.2–28.9, HK-spz 45 cycles in (B) and fresh-RAS 6.5 × 107–1.5 × 108, cryo-RAS 8.2 × 106–1.5 × 107, HK-spz zero 18S copies in (C). Kruskal–Wallis with Dunn’s multiple comparisons test: fresh-RAS vs. all other groups. ND = not detected. * P < 0.05, ** P < 0.005, **** P < 0.0001.