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Vector Competence Analyses on Aedes aegypti Mosquitoes using Zika Virus
Published on: May 31, 2020
Laboratory strains of Aedes aegypti are competent to Brazilian Zika virus
André Luis Costa-da-Silva1,2, Rafaella Sayuri Ioshino1,2, Helena Rocha Corrêa de Araújo1,2
1Departamento de Parasitologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, São Paulo, Brasil.
Abstract:
The Zika virus outbreaks are unprecedented human threat in relation to congenital malformations and neurological/autoimmune complications. Since this virus has high potential to spread in regions presenting the vectors, improvement in mosquito control is a top priority. Thus, Aedes aegypti laboratory strains will be fundamental to support studies in different research fields implicated on Zika-mosquito interactions which are the basis for the development of innovative control methods. In this sense, our aim was to determine the main infection aspects of a Brazilian Zika strain in reference Aedes aegypti laboratory mosquitoes. We orally exposed Rockefeller, Higgs and Rexville mosquitoes to the Brazilian ZIKV (ZIKVBR) and qRT-PCR was applied to determine the infection, dissemination and detection rates of ZIKV in the collected saliva as well as viral levels in mosquito tissues. The three strains sustain the virus development but Higgs showed significantly lower viral loads in bodies at 14 days post-infection (dpi) and the lowest prevalences in bodies and heads. The Rockefeller strain was the most susceptible at 7 dpi but similar dissemination rates were observed at 14 dpi. Although variations exist, the ZIKVBR RNA shows detectable levels in saliva of the three strains at 14 dpi but is only detected in Rockefeller at 7 dpi. Moreover, saliva samples from the three strains were confirmed to be infectious when intrathoracically injected into mosquitoes. The ZIKVBR kinetics was monitored in Rockefeller mosquitoes and virus could be identified in the heads at 4 dpi but was more consistently detected late in infection. Our study presents the first evaluation on how Brazilian Zika virus behaves in reference Aedes aegypti strains and shed light on how the infection evolves over time. Vector competence and hallmarks of the ZIKVBR development were revealed in laboratory mosquitoes, providing additional information to accelerate studies focused on ZIKV-mosquito interactions.
Insights
This study shows how the Brazilian Zika virus (ZIKVBR) infects different Aedes aegypti mosquito strains. While all strains sustain the virus, variations in viral load and saliva infectivity were observed, impacting Zika transmission potential.
Area of Science:
- Medical Entomology
- Virology
- Infectious Diseases
Background:
- Zika virus (ZIKV) outbreaks pose significant threats, causing congenital malformations and neurological complications.
- Effective mosquito control is crucial due to the virus's high spread potential via vectors like Aedes aegypti.
- Understanding ZIKV-mosquito interactions is key for developing innovative control strategies.
Purpose of the Study:
- To evaluate the infection dynamics of a Brazilian ZIKV strain in reference Aedes aegypti laboratory mosquito strains.
- To determine infection, dissemination, and detection rates of ZIKV in mosquito tissues and saliva.
- To assess the infectivity of ZIKV-infected mosquito saliva.
Main Methods:
- Oral exposure of Rockefeller, Higgs, and Rexville Aedes aegypti strains to Brazilian ZIKV (ZIKVBR).
- Quantitative reverse transcription PCR (qRT-PCR) to measure viral loads in mosquito bodies, heads, and saliva.
- Intrathoracic injection of mosquito saliva into other mosquitoes to assess infectivity.
Main Results:
- All three mosquito strains supported ZIKV development, with Higgs exhibiting lower viral loads and prevalence at 14 days post-infection (dpi).
- Rockefeller strain showed higher susceptibility at 7 dpi, with detectable ZIKV RNA in saliva by 7 dpi, and in all strains by 14 dpi.
- Infectious ZIKV was detected in the saliva of all strains by 14 dpi, and ZIKVBR was detected in Rockefeller mosquito heads as early as 4 dpi.
Conclusions:
- This study provides the first evaluation of Brazilian ZIKV behavior in reference Aedes aegypti strains.
- Variations in vector competence and ZIKV development were observed among strains, offering insights into transmission dynamics.
- Findings contribute crucial data for accelerating research on ZIKV-mosquito interactions and control methods.
