No evidence for local adaptation of dengue viruses to mosquito vector populations in Thailand.
Despite their epidemiological importance, the evolutionary forces that shape the spatial structure of dengue virus genetic diversity are not fully understood. Fine-scale genetic structure of mosquito vector populations and evidence for genotype × genotype interactions between dengue viruses and their mosquito vectors are consistent with the hypothesis that the geographical distribution of dengue virus genetic diversity may reflect viral adaptation to local mosquito populations. To test this hypothesis, we measured vector competence in all sympatric and allopatric combinations of 14 low-passage dengue virus isolates and two wild-type populations of Aedes aegypti mosquitoes sampled in Bangkok and Kamphaeng Phet, two sites located about 300 km apart in Thailand. Despite significant genotype × genotype interactions, we found no evidence for superior vector competence in sympatric versus allopatric vector-virus combinations. Viral phylogenetic analysis revealed no geographical clustering of the 14 isolates, suggesting that high levels of viral migration (gene flow) in Thailand may counteract spatially heterogeneous natural selection. We conclude that it is unlikely that vector-mediated selection is a major driver of dengue virus adaptive evolution at the regional scale that we examined. Dengue virus local adaptation to mosquito vector populations could happen, however, in places or times that we did not test, or at a different geographical scale.
Department of Entomology Armed Forces Research Institute of Medical Sciences Bangkok Thailand.
Thanyalak
T
Fansiri
Department of Entomology Armed Forces Research Institute of Medical Sciences Bangkok Thailand.
Arissara
A
Pongsiri
Department of Virology Armed Forces Research Institute of Medical Sciences Bangkok Thailand.
Chonticha
C
Klungthong
Department of Entomology Armed Forces Research Institute of Medical Sciences Bangkok Thailand.
Alongkot
A
Ponlawat
Department of Virology Armed Forces Research Institute of Medical Sciences Bangkok Thailand.
Butsaya
B
Thaisomboonsuk
Department of Virology Armed Forces Research Institute of Medical Sciences Bangkok Thailand; Present address: Viral Diseases Branch Walter Reed Army Institute of Research Silver Spring MD USA.
Richard G
RG
Jarman
Department of Entomology and Nematology University of California Davis CA USA; Fogarty International Center National Institutes of Health Bethesda MD USA.
Thomas W
TW
Scott
Insect-Virus Interactions Group Department of Genomes and Genetics Institut Pasteur Paris France; Unité de Recherche Associée Centre National de la Recherche Scientifique Paris France.
Louis
L
Lambrechts
Aedes aegypti; dengue virus; genotype × genotype interactions; local adaptation; population structure