Abstract
BackgroundDengue virus (DENV) is the arbovirus with the highest incidence in New Caledonia and in the South Pacific region. In 2012–2014, a major DENV-1 outbreak occurred in New Caledonia. The only known vector of DENV in New Caledonia is Aedes aegypti but no study has yet evaluated the competence of New Caledonia Ae. aegypti populations to transmit DENV. This study compared the ability of field-collected Ae. aegypti from different locations in New Caledonia to transmit the DENV-1 responsible for the 2012–2014 outbreak. This study also aimed to compare the New Caledonia results with the vector competence of Ae. aegypti from French Polynesia as these two French countries have close links, including arbovirus circulation.MethodsThree wild Ae. aegypti populations were collected in New Caledonia and one in French Polynesia. Female mosquitoes were orally exposed to DENV-1 (106 FFU/ml). Mosquito bodies (thorax and abdomen), heads and saliva were analyzed to measure infection, dissemination, transmission rates and transmission efficiency, at 7, 14 and 21 days post-infection (dpi), respectively.ResultsDENV-1 infection rates were heterogeneous, but dissemination rates were high and homogenous among the three Ae. aegypti populations from New Caledonia. Despite this high DENV-1 dissemination rate, the transmission rate, and therefore the transmission efficiency, observed were low. Aedes aegypti population from New Caledonia was less susceptible to infection and had lower ability to transmit DENV-1 than Ae. aegypti populations from French Polynesia.ConclusionThis study suggests that even if susceptible to infection, the New Caledonian Ae. aegypti populations were moderately competent vectors for DENV-1 strain from the 2012–2014 outbreak. These results strongly suggest that other factors might have contributed to the spread of this DENV-1 strain in New Caledonia and in the Pacific region.
Highlights
Dengue virus (DENV) is the arbovirus with the highest incidence in New Caledonia and in the South Pacific region
Other studies showed that vector competence for DENV may be linked to the genetic background of the vector, such as genes related to the midgut escape barrier, notably the Quantitative Trait Loci (QTL) on the chromosome III [16,17,18]
The number of infected mosquitoes obtained for Nouméa and Poindimié were low after 14 dpi, the dissemination rate seems more homogenous among the three New Caledonia (NC) populations (80–100% of dissemination)
Summary
Dengue virus (DENV) is the arbovirus with the highest incidence in New Caledonia and in the South Pacific region. This study compared the ability of field-collected Ae. aegypti from different locations in New Caledonia to transmit the DENV-1 responsible for the 2012–2014 outbreak. This study aimed to compare the New Caledonia results with the vector competence of Ae. aegypti from French Polynesia as these two French countries have close links, including arbovirus circulation. The epidemiology of dengue, Calvez et al Parasites & Vectors (2017) 10:381 is heterogeneous; Small Pacific Island Countries and Territories (PICTs) are affected by DENV transmission for a few months only, while larger PICTs, like New Caledonia (NC) or French Polynesia (FP), may experience active circulation of a single serotype/genotype for several years until the emergence of a new epidemic viral strain [4,5,6,7,8]. Other studies showed that vector competence for DENV may be linked to the genetic background of the vector, such as genes related to the midgut escape barrier, notably the Quantitative Trait Loci (QTL) on the chromosome III [16,17,18]
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