Article
Extended Data Fig. 2 | Invasion process across Dantu genotype groups
studied by time-lapse video microscopy. a, The force of RBC detachment
from a merozoite was measured using optical tweezers across genotype
groups. RBCs attached to merozoites were pulled using optical traps, and the
adhesive forces at the merozoite–RBC interface were quantified by evaluating
the elastic morphological response of the RBCs as they resisted merozoite
detachment. Means and standard deviations (s.d.) are shown in Supplementary
Table 3. Six biologically independent samples per genotype group were tested,
obtaining 21 events for non-Dantu individuals, 19 for Dantu heterozygotes,
and 24 for Dantu homozygotes. The experimentalist was blinded to the RBC
genotype group. The median is indicated by the middle red line in the boxplots,
with the 25th and 75th percentiles indicated by the tops and bottoms of each
plot, and the total data range shown by whiskers. If the median is not centred in
the box, it shows sample skewness. Pairwise comparisons between genotype
groups were performed using the two-sided Mann–Whitney U-test. b, The
degree to which merozoites deformed RBCs during invasion is given by a
simplified four-point deformation scale (0, 1, 2 and 3), with 3 indicating the
most extreme degree of deformation achieved^10. The degree of deformation
was compared across genotype groups with no significant difference
noticed, and between successful and failed invasions. The percentage of RBCs
undergoing strong deformations (score 2/3) is substantially higher in the case
of successful invasions, while RBCs that were contacted but not invaded
experience weak deformations (score 0/1). Data are from 155 cells for
non-Dantu individuals, 191 for Dantu heterozygotes, and 233 for Dantu
homozygotes. Numbers of successfully invaded cells are 53 for non-Dantu,
43 for Dantu heterozygote, and 41 for Dantu homozygote. The visual
assessment was made with blinded data by two different experimentalists.
c, Successful invasions are usually followed by a reversible echinocyte phase
that lasts between 5 min and 11 min^31 , until the recovery of newly infected RBC
biconcave shape. The duration of echinocytosis here is in agreement with the
literature and not significantly different across genotype groups; data from
53 cells non-Dantu, 43 Dantu heterozygotes and 41 Dantu homozygotes.