Epidémiologie moléculaire, évolution et diversité génétique intra-hôte du virus de la Dengue dans les Etats insulaires du Pacifique Sud
Auteur / Autrice : | Maite Tepoe Aubry |
Direction : | Marcel Le Pennec, John Aaskov, Van-Mai Cao-Lormeau |
Type : | Thèse de doctorat |
Discipline(s) : | Biologie cellulaire et moléculaire |
Date : | Soutenance en 2012 |
Etablissement(s) : | Polynésie française |
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Mots clés contrôlés
Résumé
Dengue virus (DENV) is constantly evolving as a result of constraints inherent to the host and the context of transmission. We proposed to analyze the genetic evolution of DENV at different levels of evolutionary divergence: at inter-hosts level, in the regional context of the South Pacific and local contexts of the island countries; and at intra-host level, during infection in human. By analyzing the genome of nearly 500 DENV strains collected over the past 25 years in the South Pacific Island countries (SPICs), we identified South-East Asia as the major source of viral introduction in the South Pacific and showed the existence of preferential pathways of virus distribution between SPICs. Moreover, we revealed the fixation of mutations within the viral genome, signatures of the impact of regional and local contexts on the genetic evolution of DENV. Through the analysis of clonal sequences of the complete envelope (E) gene of DENV-4 strains obtained from venous and capillary blood samples collected during 3 consecutive days in several patients, we showed that at all levels of evolutionary divergence, the sereotype 4 displays lower genetic variability than the three others. At intra-host level, we observed that the viral genetic diversity evolves during infection and is lower in capillary blood. Our results support the hypothesis of an active viral replication in the vicinity of blood capillaries of the skin and show the existence of an impact of the immune response on the structure of the viral population during infection.