Two Chikungunya Isolates from the Outbreak of La Reunion (Indian Ocean) Exhibit Different Patterns of Infection in the Mosquito, Aedes albopictus

Abstract

BackgroundA Chikungunya (CHIK) outbreak hit La Réunion Island in 2005–2006. The implicated vector was Aedes albopictus. Here, we present the first study on the susceptibility of Ae. albopictus populations to sympatric CHIKV isolates from La Réunion Island and compare it to other virus/vector combinations.Methodology and FindingsWe orally infected 8 Ae. albopictus collections from La Réunion and 3 from Mayotte collected in March 2006 with two Chikungunya virus (CHIKV) from La Réunion: (i) strain 05.115 collected in June 2005 with an Alanine at the position 226 of the glycoprotein E1 and (ii) strain 06.21 collected in November 2005 with a substitution A226V. Two other CHIKV isolates and four additional mosquito strains/species were also tested. The viral titer of the infectious blood-meal was 107 plaque forming units (pfu)/mL. Dissemination rates were assessed by immunofluorescent staining on head squashes of surviving females 14 days after infection. Rates were at least two times higher with CHIKV 06.21 compared to CHIKV 05.115. In addition, 10 individuals were analyzed every day by quantitative RT-PCR. Viral RNA was quantified on (i) whole females and (ii) midguts and salivary glands of infected females. When comparing profiles, CHIKV 06.21 produced nearly 2 log more viral RNA copies than CHIKV 05.115. Furthermore, females infected with CHIKV 05.115 could be divided in two categories: weakly susceptible or strongly susceptible, comparable to those infected by CHIKV 06.21. Histological analysis detected the presence of CHIKV in salivary glands two days after infection. In addition, Ae. albopictus from La Réunion was as efficient vector as Ae. aegypti and Ae. albopictus from Vietnam when infected with the CHIKV 06.21.ConclusionsOur findings support the hypothesis that the CHIK outbreak in La Réunion Island was due to a highly competent vector Ae. albopictus which allowed an efficient replication and dissemination of CHIKV 06.21.

Ecología de Aedes aegypti y Aedes albopictus en América y la transmisión de enfermedades

“…Aedes albopictus también es un vector competente del virus chikungunya y, bajo ciertas circunstancias, puede ser mejor que Ae. aegypti (40). Las recientes epidemias en la región del Océano Indico, demuestran que la expansión de Ae.…”

Aedes albopictus, vecteur des virus du chikungunya et de la dengue à la Réunion : biologie et contrôle

“…Néanmoins, depuis les épidémies du SOOI, la capacité d'Ae. albopictus à transmettre efficacement ce virus a été démon-trée (Pagès et al, 2006;Reiter et al, 2006;Vazeille et al, 2007 ;Grandadam & Delatte, non publié). Aedes albopictus (Skuse, 1894) est un moustique originaire des forêts d'Asie du Sud-Est (Smith, 1956) qui s'est progressivement adapté à l'environnement humain qui prodigue sources de sang (homme et animaux domestiques) et collections d'eau nécessaires au déve-loppement des larves.…”

“…Des expé-riences récentes, réalisées à partir de populations d'Ae. albopictus de la Réunion, ont montré que la compé-tence vectorielle vis-à-vis du CHIKV variait en fonction de la souche virale et en fonction de la population de moustiques (Vazeille et al, 2007 (Schuffenecker et al, 2006). Une répli-cation plus importante de ce génotype pourrait expliquer l'extrême efficacité de transmission des Ae.…”

Chikungunya virus infection in developing countries - What should we do?

“…The virus is transmitted mainly through Aedes mosquitoes. Chikungunya fever is endemic in many countries of Africa and Asia including Bangladesh where the Aedes mosquitoes (A. aegypti and A. albopictus) (Figure 1) are found (Vazeille et al, 2007). The virus affects all age groups, but severe illness occurs in older people (≥65 years) and children (Hoque and Ahmed, 2012).…”