Oral challenge of Ae. aegypti (HWE strain) with DENV2 strains and midgut escape isolates. One week post-emergence, females of the laboratory adapted Higgs White Eye (HWE) strain received artificial bloodmeals containing (A) DENV2-PR159 (American genotype DENV2 from Puerto-Rico), EM41 (midgut escape mutant derived from the PR159 strain), or DENV2-Jam1409 (American-Asian genotype DENV2 from Jamaica as control); (B) DENV2-QR94 (American genotype DENV2 from Quintana Roo, Mexico), EM33 (midgut escape mutant derived from the QR94 strain), or DENV2-Jam1409. Viruses had been propagated for 12–14 days in C6/36 cells. Artificial bloodmeals consisted of infected C6/36 cell culture supernatants mixed at a 1:1 ratio with defibrinated sheep blood. Virus titers in the bloodmeals ranged from 7×106-1×107 pfu/ml. Mosquitoes were allowed to feed for 1 h. At 14 days post-bloodmeal (pbm), virus titers of individual midguts and carcasses were assayed by plaque assays in LLC-MK2 (monkey kidney) cells. Bars in the diagram represent mean values. * indicate significant difference between mean titers as analyzed on Y = Log(Y) transformed data by ANOVA and Bonferroni’s Multiple Comparison Test.