Table 1. Effect of freeze thawing on survival of T. cruzi trypomastigote and amastigote stages.
CL Brener Luc trypomastigote spiked mouse blood and T. cruzi-infected Vero cells were subjected to three freeze-thaw cycles (F-T), before being incubated with fresh Vero cells and monitored for trypomastigote emergence over 28 days. Three technical replicates, mean (standard deviation).
| Sample | CL Brener Luciferase Trypomastigote Counts ml-1 | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Day | |||||||||
| 0 | 1 | 3 | 7 | 10 | 14 | 21 | 24 | 28 | |
| F-T Spiked blood + H2O | 106 | -/-/- | -/-/- | -/-/- | -/-/- | -/-/- | -/-/- | -/-/- | -/-/- |
| F-T Spiked blood | 107 | -/-/- | -/-/- | -/-/- | -/-/- | -/-/- | -/-/- | -/-/- | -/-/- |
| F-T Infected Vero cells | * | -/-/- | -/-/- | -/-/- | -/-/- | -/-/- | -/-/- | -/-/- | -/-/- |
| Control Spiked blood + H2O | 106 | -/-/- | -/-/- | -/-/- | +/+/+ | 3x104 (2x104) | 3x104 (1x104) | nd | nd |
| Control Spiked blood | 107 | -/-/- | -/-/- | +/+/+ | 2x104 (0) | 2x105 (6x104) | nd | nd | nd |
| Control Infected Vero Cells | * | -/-/- | -/-/- | +/+/+ | 3x105 (2x104) | nd | nd | nd | nd |
* Infected Vero cells were harvested after 5 days T. cruzi infection (MOI10), resuspended at 106 ml-1, freeze-thawed and control samples were subsequently incubated with 105 ml-1 Vero cells
+/+/+ Motile trypomastigotes observed in all three replicates, but below limit of quantitation 2x104 ml-1
-/-/- No motile trypomastigotes observed in all three replicates
nd Not done