Sequential Infection of Aedes aegypti Mosquitoes with Chikungunya Virus and Zika Virus Enhances Early Zika Virus Transmission.

Tereza Magalhaes,William Black,Gregory Ebel,Claudia Rückert,Brian Foy,Alexis Robison,Michael Young

doi:10.3390/insects9040177

Abstract

In urban settings, chikungunya, Zika, and dengue viruses are transmitted by Aedes aegypti mosquitoes. Since these viruses co-circulate in several regions, coinfection in humans and vectors may occur, and human coinfections have been frequently reported. Yet, little is known about the molecular aspects of virus interactions within hosts and how they contribute to arbovirus transmission dynamics. We have previously shown that Aedes aegypti exposed to chikungunya and Zika viruses in the same blood meal can become coinfected and transmit both viruses simultaneously. However, mosquitoes may also become coinfected by multiple, sequential feeds on single infected hosts. Therefore, we tested whether sequential infection with chikungunya and Zika viruses impacts mosquito vector competence. We exposed Ae. aegypti mosquitoes first to one virus and 7 days later to the other virus and compared infection, dissemination, and transmission rates between sequentially and single infected groups. We found that coinfection rates were high after sequential exposure and that mosquitoes were able to co-transmit both viruses. Surprisingly, chikungunya virus coinfection enhanced Zika virus transmission 7 days after the second blood meal. Our data demonstrate heterologous arbovirus synergism within mosquitoes, by unknown mechanisms, leading to enhancement of transmission under certain conditions.

Highlights

Chikungunya virus (CHIKV; genus Alphavirus) and Zika virus (ZIKV; genus Flavivirus) are both arthropod-borne viruses that have recently emerged in the Americas
Ae. aegypti mosquitoes were first exposed to either CHIKV, ZIKV, or an uninfected blood meal, given the opportunity to lay eggs and again fed with either CHIKV, ZIKV, or an uninfected blood meal 7 days after the initial blood meal, resulting in six treatment groups (Figure 1)
The infection rates were again high for all groups (100% for CHIKV; >96% for ZIKV), and an established infection with CHIKV or ZIKV had no significant impact on ZIKV and CHIKV infection rates

Summary

Introduction

Chikungunya virus (CHIKV; genus Alphavirus) and Zika virus (ZIKV; genus Flavivirus) are both arthropod-borne viruses that have recently emerged in the Americas. Fever are highly similar and include fever, arthralgia, myalgia, rash, and conjunctivitis [3]. Both viruses can cause severe disease manifestations such as persistent arthralgia or neurological symptoms [3,4]. ZIKV has been associated with infection of the developing fetus in pregnant women, resulting in Zika congenital syndrome [5]. In urban settings, both viruses are transmitted by Aedes aegypti and Aedes albopictus mosquitoes and have rapidly spread across most areas of the Americas where these mosquitoes are established. Females generally feed on humans several times throughout their lives, including

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