We hypothesize the possible route of introduction of the cosmopolitan DENV-2 genotype into Brazil through the border with Peru. The five sequences presented in this study create a geographical link with the three others sequences of this genotype already recorded on the continent.

Dengue virus serotype 2 (DENV-2) is responsible for dengue epidemics on a global scale and is recognized for being associated with severe cases of the disease. This study conducted the phylogenetic investigation of DENV-2 in the Northern region of Brazil. DENV-2 isolates from 2017 to 2021, originating from Northern Brazilian states, were selected. Only one lineage (I) of the Asian-American genotype and one lineage (5) of the cosmopolitan genotype were observed. All sequences of the Asian-American genotype used in this study were segregated into a paraphyletic subgroup aligned with sequences from an American clade. These results indicate a probable geographic link starting from Puerto Rico. Additionally, sequences from Acre were identified and grouped into a monophyletic clade of the cosmopolitan genotype. These results indicate the cocirculation of two DENV-2 distinct lineages: Lineage 1, Asian-American genotype (probable origin from Puerto Rico); Lineage 5, cosmopolitan genotype (probable origin from Peru). Our results provide important data regarding the study of DENV genotypes and lineages distribution, as well as opening up possibilities for probable introduction and dissemination routes.

To assess the genetic diversity of circulating dengue virus 2 in Senegal in 2018 we performed molecular characterization by complete genome sequencing and performing phylogenetic analysis. Sequenced strains belong to Cosmopolitan genotype of DENV-2 we observed intra-genotype variability leading to a divergence in two clades with differential geographic distribution. We report two variants namely; the “Northern variant” harbouring three nonsynonymous mutations (V1183M, R1405K, P2266T) located respectively on NS2A, NS2B and NS4A and the “Western variant” with two nonsynonymous mutations (V1185E, V3214E) located respectively in the NS2A gene and the NS5 gene. Findings calls for in depth in vitro and functional study to elucidate the impact of observed mutations on viral fitness, spread, epidemiology and disease outcome.

Globally 390 millions of people are at risk of dengue infection; over the past 50 years the virus incidence increased thirty-fold. In Senegal, an unprecedented occurrence of outbreaks and sporadic cases was noticed since 2017. In October 2018 an outbreak of DENV-2 was reported in Rosso area in the north of Senegal at the border with Mauritania. Out of the 187 blood specimen samples collected, 27 were positives by qRT-PCR and 8 were serologically positive for DENV IgM. Serotyping using qRT-PCR reveals that isolates were positive for DENV-2. A subset of DENV-2 positives samples was selected and subjected to full genome sequencing followed by phylogenetic analysis. Analysis of 06 nearly completed genome sequences (n= 6) revealed that isolates belong to the cosmopolitan genotype and are closely related to the Mauritanian strains detected between 2017 and 2018 and those detected in many West African countries such as Burkina Faso or Cote d’Ivoire. Our results suggest a transboundary circulation of the DENV-2 cosmopolitan genotype between Senegal and Mauritania and call for a need of coordinated surveillance of arboviruses between these two countries. Interestingly, high level of homology between West African isolates highlights endemicity and call for a set-up of sub-regional viral genomic surveillance which will lead to a better understanding of viral dynamic, transmission and spread across Africa.