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Table 1 Comparison of RSA protocols

From: Alternative methods for the Plasmodium falciparum artemisinin ring-stage survival assay with increased simplicity and parasite stage-specificity

Variables Percoll gradient RSA [8] Sorbitol-only RSA Filtration RSA
Chemicals required during RSAa Heparin, percoll, sorbitol Sorbitol None
Volume of parasite culture needed ≥300 µL packed RBCs at 2 % parasitemia 40 µL packed RBCs at 1 % parasitemia ≥1.5 mL packed RBCs at 2–3 % parasitemia
Number of steps until completion 17 10 12
Preparation time, before drug pulse 4.5 h 30 min 3 h
Total time of parasite incubation from drug pulse 66 h 66 h 66 or 90 h, if DMSO <0.40 % at 66 h
Stage distribution at time of drug pulse 80 % rings, 20 % trophozoites and schizonts Mixture of young and older rings 3 h rings only
Presence of pyknotic parasites in read out Yes Yes No
  1. aAll methods require sorbitol synchronization two parasite cycles before performing RSA