Nature | Vol 577 | 16 January 2020 | 379of pyrethroid insecticides^6 ,^7 (deltamethrin: CYP6M2, IC 50 = 4.24 μM
and CYP6P3, IC 50 = 3.17 μM; permethrin: CYP6M2, IC 50 = 8.07 μM and
CYP6P3, IC 50 = 6.77 μM)^18. The binding of the pyrethroids to SAP2
had significantly higher specificity (analysis of variance (ANOVA),
P < 0.0001) than the other SAP proteins; however, both SAP1 and SAP3
bound weakly to deltamethrin (IC 50 > 10 μM) and SAP1 bound moder-
ately to α-cypermethrin (IC 50 = 9.02 μM).
Having established the importance of SAP2 expression for the resist-
ance of mosquitoes to pyrethroids in a laboratory setting, and having
detected the overexpression of this transcript in available transcrip-
tomic data from multiple resistant West African field populations
(Fig. 3a and Extended Data Table 1), we next looked for evidence of
selection at this locus, using data from the Anopheles gambiae 1000
Genomes Project^19 and further de novo sequencing. We computed(^020102012201420162018)
0.2
0.4
0.6
A. gambiae
Cameroon
Guinea
Burkina Faso
3R
AG1000
modi cation
SAP2
a
b
c
4835785 4853985
3R 4.85 Mb
SAP2
Fold change of less than 1
Fold change of between 1 and 5
Fold change of greater than 5
d’IvoireCôte
Burkina
Faso
Cameroon
Guinea
Bioko
Island
West Africa
AG
T C
T A
GA
AG
SAP2
2010 2012 2014 2016 2018
0
0.2
0.4
0.6
A. coluzzii
Allele fr
equency
5.0
2.5
0
|iHS|
0.2
0.1
p(|iHS| >2.5^0
V)
Genes
- 3.00 3.50 4.00 4.50 5.00 5.50 6.00 6.50
Genomic position (Mb)
Year Ye ar4845928
4845931
4846007
4846027
4846066Fig. 3 | SAP2 is upregulated and under selection in multiple countries
across West Africa. a, Points represent significantly differential expression
of SAP2 in pyrethroid-resistant mosquitoes in two sister species (A. coluzzii
and A. gambiae) compared with susceptible populations (supplementary
table 1 from a previously published study^10 ). Significant (limma; Benjamini–
Hochberg-corrected P value^10 , P ≤ 0.05) fold changes are shown in green,
orange and red. Countries in which SAP2 is significantly upregulated and/or
involved in the selective sweep are highlighted with a pin. No transcriptomic
data are available for Guinea. The map was created specifically for this
manuscript by M. Bernardi. b, Left, schematic of the range of the selective
sweep found in Guinea, Burkina Faso and Cameroon with a selective sweep
found across these regions in the Anopheles gambiae 1000 Genomes Project
highlighted in grey^19. Right, the observed iHS signal from Guinea is shown as
follows (from top to bottom): raw iHS statistics per SNP, normalized by
chromosome in allele frequency bins; summarized iHS in windows of 20 kb
by proportion (p) of SNPs exceeding 2.5 standard deviations^20 ; and genes
in this region with SAP2 annotated. The range of the 55 SNPs with this
haplotype across the three countries is highlighted in yellow. Bottom right,
a magnified area shows the approximate location of the five haplotype-
associated SNPs in proximity to SAP2 (Extended Data Fig. 1a). c, Fitted trend
in frequency of the derived haplotype-associated SNPs in field populations
from Burkina Faso. A. coluzzii populations collected from Tengrela from 2011
to 2018 (left) and A. gambiae s.s. samples collected in 2013 and 2015 from
Bakaridjan, Burkina Faso and 2018 from Tiefora, Burkina Faso (right). Dates
when samples were sequenced are indicated by a dotted line. SNP data are
shown in the legend, including the locus and the alternate allele (left) and
PEST allele (right).