Three different DENV-3 genotypes were detected during the study: genotype I, genotype II, and genotype III (Figure S3). Data obtained on DENV-3 strains from European travelers confirmed the current circulation

of genotypes I (1 strain) and III (17 strains) in the Americas (Figure S3). These results describe for the first time the presence of genotype I in Ecuador, and are in agreement with the recent detection of the co-circulation in Brazil and Colombia of genotypes I and III.26,27 Two African DENV-3 strains were detected within our study population, ABT-199 price both belonging to genotype III. Interestingly, the strain detected from Cameroon clustered in the same clade like other previously reported African isolates from Mozambique and Somalia, whereas the strain detected from Senegal was shown to be related to recently reported American strains in the same genotype, which might indicate a different origin of this genotype in the area (Figure S3). Three different genotypes were identified among DENV-3 strains detected in travelers returning form Asia: those strains from the Philippines joined genotype I; strains from the signaling pathway Indian subcontinent

clustered within genotype III; and strains from Thailand, Cambodia, and Vietnam grouped within genotype II (Figure S3). In our analysis, five different genotypes were differentiated in DENV-4: genotype I, genotype II, genotype III, genotype sylvatic, and a not previously reported genotype IV (Figure S4). In the set of sequences analyzed, a sequence divergence of more than 6% was observed between the strains that clustered in this group and those comprising other genotypes.

When the complete E gene was analyzed, this classification new was supported. An additional analysis by maximum likelihood method confirmed the possible existence of a new clade (Figure S8). All DENV-4 strains from the Americas (n = 11) belonged to genotype II which has been the genotype circulating in the region since its introduction in 1982 (Figure S4). Remarkably, a cluster of Cuba DENV-4 strains from four patients traveling to Cuba at different times during summer 2006 suggested the presence of an outbreak in the country during this time.28 These strains were also similar to those detected in travelers returning from Venezuela and Ecuador from 2005 to 2007, strongly suggesting a possible re-emergence of this serotype in the region (Figure S4). No DENV-4 samples from Africa were detected within our study population. All DENV-4 Asian strains detected in travelers clustered within genotype I (Figure S4). Molecular epidemiological studies on dengue are crucial for the understanding of the transmission patterns of the viruses and for tracking the spread of dengue strains around the world.