Genetic specificity and potential for local adaptation between dengue viruses and mosquito vectors.
BACKGROUND
Several observations support the hypothesis that vector-driven selection plays an important role in shaping dengue virus (DENV) genetic diversity. Clustering of DENV genetic diversity at a particular location may reflect underlying genetic structure of vector populations, which combined with specific vector genotype x virus genotype (G x G) interactions may promote adaptation of viral lineages to local mosquito vector genotypes. Although spatial structure of vector polymorphism at neutral genetic loci is well-documented, existence of G x G interactions between mosquito and virus genotypes has not been formally demonstrated in natural populations. Here we measure G x G interactions in a system representative of a natural situation in Thailand by challenging three isofemale families from field-derived Aedes aegypti with three contemporaneous low-passage isolates of DENV-1.


RESULTS
Among indices of vector competence examined, the proportion of mosquitoes with a midgut infection, viral RNA concentration in the body, and quantity of virus disseminated to the head/legs (but not the proportion of infected mosquitoes with a disseminated infection) strongly depended on the specific combinations of isofemale families and viral isolates, demonstrating significant G x G interactions.


CONCLUSIONS
Evidence for genetic specificity of interactions in our simple experimental design indicates that vector competence of Ae. aegypti for DENV is likely governed to a large extent by G x G interactions in genetically diverse, natural populations. This result challenges the general relevance of conclusions from laboratory systems that consist of a single combination of mosquito and DENV genotypes. Combined with earlier evidence for fine-scale genetic structure of natural Ae. aegypti populations, our finding indicates that the necessary conditions for local DENV adaptation to mosquito vectors are met.
Lambrechts
Louis
L
Department of Entomology, University of California, One Shields Avenue, Davis, CA 95616, USA. Louis.Lambrechts@mpl.ird.fr
Chevillon
Christine
C
Albright
Rebecca G
RG
Thaisomboonsuk
Butsaya
B
Richardson
Jason H
JH
Jarman
Richard G
RG
Scott
Thomas W
TW
D000220:Adaptation, Biological / Q000235:genetics*; D000330:Aedes / Q000235:genetics* / Q000821:virology*; D000818:Animals; D003716:Dengue Virus / Q000235:genetics*; D005260:Female; D005838:Genotype; D054884:Host-Pathogen Interactions; D007303:Insect Vectors / Q000235:genetics / Q000821:virology; D011110:Polymorphism, Genetic; D012367:RNA, Viral / Q000032:analysis; D013045:Species Specificity; D013785:Thailand
D012367:RNA, Viral