Table 1.
Plasmodium falciparum-specific peaks found by MALDI-TOF analysis
| Sample type | |||||||||||||||
| Culture type | 3D7 | HB3 | IT4 | NC | 3D7 | NC | 3D7 | NC | 3D7 | NC | 3D7 | NC | 3D7 | NC | |
| % Culture | 100 | 100 | 100 | 100 | 50 | 50 | 25 | 25 | 12,5 | 12,5 | 7,5 | 7,5 | 4 | 4 | |
| % EDTA dilution | 0 | 0 | 0 | 0 | 50 | 50 | 75 | 75 | 87,5 | 87,5 | 92,5 | 92,5 | 96 | 96 | |
| Microscopy results | |||||||||||||||
| Ring stages | 54 | 49 | 30 | 0 | 32 | 0 | 13 | 0 | 7 | 0 | 4 | 0 | 2 | 0 | |
| Late stages | 8 | 9 | 9 | 0 | 6 | 0 | 3 | 0 | 1 | 0 | 0 | 0 | 0 | 0 | |
| Total IRBC | 3,1% | 2.9% | 2.5% | None | 1,9% | None | 0,80% | None | 0,40% | None | 0,20% | None | 0,10% | None | |
| MALDI-TOF results | |||||||||||||||
| Successful runs | 3 of 3 | 3 of 3 | 3 of 3 | 3 of 3 | 3 of 3 | 3 of 3 | 3 of 3 | 3 of 3 | 3 of 3 | 3 of 3 | 2 of 3 | 3 of 3 | 3 of 3 | 3 of 3 | |
| MALDI-TOF diagnose | Pos | Pos | Pos | Neg | Pos | Neg | Pos | Neg | Pos | Neg | Pos | Neg | Pos | Neg | |
| Peaks found (m/z) | |||||||||||||||
| 1014 | + | + | + | – | + | – | + | – | – | – | – | – | – | – | |
| 1130 | + | + | + | – | + | – | + | – | + | – | + | – | + | – | |
| 1366 | + | + | + | – | + | – | + | – | + | – | + | – | + | – | |
| 1470 | + | + | + | – | + | – | – | – | – | – | – | – | – | – | |
| 1657 | + | + | + | – | + | – | + | – | + | – | + | – | + | – | |
| 1984 | + | + | + | – | + | – | + | – | – | – | – | – | – | – | |
| 2006 | + | + | + | – | + | – | + | – | + | – | + | – | + | – | |
| 2473 | + | + | + | – | + | – | + | – | + | – | + | – | + | – | |
| 2527 | + | + | + | – | + | – | + | – | – | – | – | – | – | – | |
| 3176 | + | – | – | – | + | – | + | – | – | – | – | – | – | – | |
| 4042 | + | + | + | – | + | – | + | – | + | – | – | – | – | – | |
| 4300 | + | – | – | – | + | – | – | – | – | – | – | – | – | – | |
| 4332 | + | + | + | – | + | – | + | – | + | – | + | – | – | – | |
| 4421 | – | + | – | – | – | – | – | – | – | – | – | – | – | – | |
| 4432 | + | – | – | – | + | – | + | – | + | – | + | – | + | – | |
| 4704 | + | – | – | – | + | – | + | – | + | – | + | – | – | – | |
| 4765 | + | – | + | – | – | – | – | – | – | – | – | – | – | – | |
| 4773 | – | + | – | – | – | – | – | – | – | – | – | – | – | – | |
| 4957 | + | + | + | – | + | – | + | – | – | – | – | – | – | – | |
| 5547 | + | + | + | – | + | – | – | – | – | – | – | – | – | – | |
| 5567 | + | + | + | – | + | – | + | – | + | – | + | – | + | – | |
| 5705 | + | – | – | – | + | – | – | – | – | – | – | – | – | – | |
| 6086 | + | – | – | – | + | – | + | – | + | – | + | – | + | – | |
| 6286 | + | – | – | – | + | – | + | – | – | – | – | – | – | – | |
| 6500 | + | + | + | – | + | – | + | – | + | – | + | – | + | – | |
| 6533 | + | – | + | – | + | – | + | – | + | – | + | – | – | – | |
| 6760 | + | + | + | – | + | – | + | – | + | – | + | – | + | – | |
| 7886 | + | + | + | – | + | – | – | – | – | – | – | – | – | – | |
| 8086 | + | + | + | – | + | – | + | – | – | – | – | – | – | – | |
| 8568 | + | + | + | – | + | – | + | – | + | – | + | – | + | – | |
| 8843 | – | + | – | – | – | – | – | – | – | – | – | – | – | – | |
| 9340 | – | – | + | – | – | – | – | – | – | – | – | – | – | – | |
| 9409 | + | – | – | – | + | – | + | – | – | – | – | – | – | – | |
| 9530 | + | – | + | – | + | – | – | – | – | – | – | – | – | – | |
| 9546 | + | + | – | – | – | – | – | – | – | – | – | – | – | – | |
| 12,993 | + | + | + | – | + | – | + | – | + | – | + | – | + | – | |
Plasmodium falciparum-specific peaks found by MALDI-TOF analysis using different parasite strains and dilutions. + indicates the presence of a peak at the given m/z. – indicates the absence of a peak at the given m/z. 3D7, HB3 and IT4 indicate the strains of P. falciparum used in the experiment. NC = Negative control cultures consisting of uninfected erythrocytes. IRBC = Plasmodium-infected red blood cells. EDTA dilution = fresh type 0 blood in EDTA drawn from healthy subjects. Giemsa-Stained blood smears were used for microscopy. A total of 2000 red blood cells were reviewed for microscopy of each P. falciparum culture. A total of 100 microscopic fields were reviewed for negative control cultures. Mass spectra were compared by visual inspection using the FlexAnalysis software (Bruker Daltonics, Bremen, Germany) see method section for details. Plasmodium cultures and negative controls were prepared using identical steps. See method section for details