Vector competence of Aedes aegypti populations from Senegal for sylvatic and epidemic dengue 2 virus isolated in West Africa

Abstract
Vector competence of Aedes aegypti populations from six locations in different bioclimatic zones and habitats of Senegal was assessed for sylvatic (ArD 140875) and epidemic (ArA 6894) dengue 2 virus (DENV-2) isolates. F1 generation mosquitoes were fed with a blood meal containing 10(6.5) and 1.6 x 10(7) tissue culture infectious dose (TCID50) of the sylvatic DENV-2 isolate or 10(6.5) TCID50 of the epidemic isolate and incubated for 14 days. After this period, legs and wings of each individual were pooled and the corresponding body was collected separately. An immunofluorescence assay was used to test bodies and wings/legs for DENV-2 infection separately. The results showed that: (i) Senegalese Ae. aegypti populations have lower vector competence (infection rate 0-26%, dissemination rate 10-100%) for sylvatic and epidemic dengue viruses than populations from Asia and America; (ii) there was no obvious geographic variation in susceptibility among mosquito populations; (iii) the only apparent factor affecting the susceptibility was the virus titre; and (iv) except for that of Kédougou, all populations were able to disseminate the virus. Overall our findings, while extended to four other populations, confirm previous studies showing low susceptibility of Senegalese Ae. aegypti populations.