Mosquito co-infection with Zika and chikungunya virus allows simultaneous transmission without affecting vector competence of Aedes aegypti

Abstract

BackgroundZika virus (ZIKV) and chikungunya virus (CHIKV) are highly pathogenic arthropod-borne viruses that are currently a serious health burden in the Americas, and elsewhere in the world. ZIKV and CHIKV co-circulate in the same geographical regions and are mainly transmitted by Aedes aegypti mosquitoes. There is a growing number of case reports of ZIKV and CHIKV co-infections in humans, but it is uncertain whether co-infection occurs via single or multiple mosquito bites. Here we investigate the potential of Ae. aegypti mosquitoes to transmit both ZIKV and CHIKV in one bite, and we assess the consequences of co-infection on vector competence.Methodology/Principal findingsFirst, growth curves indicated that co-infection with CHIKV negatively affects ZIKV production in mammalian, but not in mosquito cells. Next, Ae. aegypti mosquitoes were infected with ZIKV, CHIKV, or co-infected via an infectious blood meal or intrathoracic injections. Infection and transmission rates, as well as viral titers of positive mosquitoes, were determined at 14 days after blood meal or 7 days after injection. Saliva and bodies of (co-)infected mosquitoes were scored concurrently for the presence of ZIKV and/or CHIKV using a dual-colour immunofluorescence assay. The results show that orally exposed Ae. aegypti mosquitoes are highly competent, with transmission rates of up to 73% for ZIKV, 21% for CHIKV, and 12% of mosquitoes transmitting both viruses in one bite. However, simultaneous oral exposure to both viruses did not change infection and transmission rates compared to exposure to a single virus. Intrathoracic injections indicate that the selected strain of Ae. aegypti has a strong salivary gland barrier for CHIKV, but a less profound barrier for ZIKV.Conclusions/SignificanceThis study shows that Ae. aegypti can transmit both ZIKV and CHIKV via a single bite. Furthermore, co-infection of ZIKV and CHIKV does not influence the vector competence of Ae. aegypti.

Entomological Coinfections of Arboviruses Dengue and Chikungunya Viruses along the Coastline of Kenya

“…In their study, Aedes albopictus was orally infected with both Dengue and Chikungunya viruses with an ability to transmit them to their human host via its saliva. A study by Göertz et al (2017); where Aedes aegypti were orally infected by Chikungunya and Zika viruses reported similar results and the vectors were highly competent, with transmission rates of up to 73% for ZIKV, 21% for CHIKV, and 12% of mosquitoes transmitting both viruses in one bite.…”

“…However, their reports are conflicting on the aspect of vector competence. Göertz et al (2017) reported co-infection of Zika and Chikungunya virus does not influence vector competence in Aedes aegypti. In contrast, report by Rückert et al (2017) says infection, dissemination and transmission of viruses by Aedes aegypti is mildly affected by co-infections of Zika, Chikungunya and Dengue viruses.…”

“…This is because mosquitoes can feed multiple times on more than one human host and require multiple bites per each gonotrophic cycle (Harrington et al, 2014). Concomitant infections were reported in studies by Göertz et al (2017), Rückert et al (2017), Le Coupanec et al (2017) and Vazeille et al (2010). However, their reports are conflicting on the aspect of vector competence.…”

“…It is worth noting that arboviruses can share a geographical area or overlap. Chikungunya and Zika viruses occur and co-circulate in same geographical zones (Göertz et al, 2017), while Dengue and Chikungunya overlap with Dengue endemic areas. Cases of arboviral co-infections in Aedes mosquitoes have been reported in areas with reports of arboviral co-infections in humans (Göertz et al, 2017), emphasizing the need to study co-infections in the vector mosquitoes.…”

“…Chikungunya and Zika viruses occur and co-circulate in same geographical zones (Göertz et al, 2017), while Dengue and Chikungunya overlap with Dengue endemic areas. Cases of arboviral co-infections in Aedes mosquitoes have been reported in areas with reports of arboviral co-infections in humans (Göertz et al, 2017), emphasizing the need to study co-infections in the vector mosquitoes. In this study, adult Aedes species mosquitoes were collected along the Kenyan coast, their species determined and screened for concomitant infections for Dengue and Chikungunya viruses over a period of two years.…”