Transmission potential of African, Asian and American Zika virus strains by Aedes aegypti and Culex quinquefasciatus from Guadeloupe (French West Indies)

Abstract

Zika virus (ZIKV) is an arbovirus that has dramatically spread in South America and the Caribbean regions since 2015. The majority of vector incrimination studies available for ZIKV showed that Aedes aegypti mosquitoes are important vectors for this virus. However, several reports suggest that Culex quinquefasciatus mosquitoes may be implicated in ZIKV transmission in certain urban settings. In the present study, we evaluated the vector competence for ZIKV of Cx. quinquefasciatus and Ae. aegypti mosquitoes from Guadeloupe using African, American and Asian strains. The results demonstrated that Cx. quinquefasciatus is refractory to ZIKV infection whatever the strain tested at 7, 14 or 21 days post-infection (dpi), while ZIKV transmission was recorded in Ae. aegypti for all the three strains. The African ZIKV strain was better transmitted by Ae. aegypti (∼ 50% mean transmission efficiency) and with a shorter incubation period (7 dpi) when compared to the Asian and American strains (<14% transmission efficiency; incubation period of 14-21 dpi). Taken together, these results suggest that only Ae. aegypti mosquitoes are involved in urban ZIKV transmission in Guadeloupe and highlight a higher infectiousness of the African ZIKV strain in this mosquito species when compared to the Asian and American ones.

Keywords: Guadeloupe; Zika virus; vector competence.

Figure 1.

Infection rate (± CI) (a), dissemination efficiency (± CI) (b), and transmission efficiency (± CI) (c) of Aedes aegypti from Guadeloupe fed with ZIKV at 7, 14 and 21 days post-infection (dpi). For each modality, a batch of 30 mosquitoes was analysed except for African ZIKV at 14 dpi (N = 25) and 21 dpi (N = 26). Asterisks indicate significant differences between the estimated parameters according to ZIKV strains and dpi (Fisher's exact test; ***: P < 0.0001). ND: Not Detected.

Figure 2.

Viral loads in saliva of Ae. aegypti infected with ZIKV Senegal, ZIKV Martinique or ZIKV Malaysia at 7, 14 and 21 days post-infection. Dots, triangles and rhombuses, represent the titer of each infected saliva. Horizontal grey bars represent means (± SE).