Abstract
Dengue virus (DENV) serotype-2 was detected in the South Pacific region in 2014 for the first time in 15 years. In 2016–2020, DENV-2 re-emerged in French Polynesia, Vanuatu, Wallis and Futuna, and New Caledonia, co-circulating with and later replacing DENV-1. In this context, epidemiological and molecular evolution data are paramount to decipher the diffusion route of this DENV-2 in the South Pacific region. In the current work, the E gene from 23 DENV-2 serum samples collected in Vanuatu, Fiji, Wallis and Futuna, and New Caledonia was sequenced. Both maximum likelihood and Bayesian phylogenetic analyses were performed. While all DENV-2 strains sequenced belong to the Cosmopolitan genotype, phylogenetic analysis suggests at least three different DENV-2 introductions in the South Pacific between 2017 and 2020. Strains retrieved in these Pacific Islands Countries and Territories (PICTs) in 2017–2020 are phylogenetically related, with strong phylogenetic links between strains retrieved from French PICTs. These phylogenetic data substantiate epidemiological data of the DENV-2 diffusion pattern between these countries.
Highlights
The first reports of dengue virus circulation in the South Pacific region date from the end of the19th century [1]
Dengue virus (DENV)-2 strains collected in Fiji, Vanuatu, Wallis and Futuna (WF), and New Caledonia (NC) between 2017 and 2020 belonged to the Cosmopolitan genotype, which was responsible for the last DENV-2 outbreak in the region in
While 1448 nt of the E gene could be sequenced from 21 samples collected in NC, WF, and Vanuatu, only 716 nt could be amplified and sequenced from the two samples collected in Fiji in
Summary
The first reports of dengue virus circulation in the South Pacific region date from the end of the. Dengue has become a major public health concern for Pacific Islands. Countries and Territories (PICTs), causing frequent outbreaks and exerting an important human and economic burden. Dengue virus (DENV) is a single-stranded, positive-sense RNA virus belonging to the genus Flavivirus, family Flaviviridae. Infection with one serotype is thought to provide life-long immune protection from reinfection by the same serotype. Based on the sequence of the envelope gene (E), each serotype may be divided into distinct genotypes, often associated with specific geographical regions [2]. In PICTs, DENV is mainly transmitted by Aedes aegypti, and by Aedes albopictus, and by some endemic vectors such as
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