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.
Highlights
The world is facing a new outbreak of the emerging Zika virus (ZIKV) [1]
ZIKVBR infection and dissemination rates in orally challenged mosquito strains To analyze and compare the infection susceptibility of Ae. aegypti laboratory strains to a ZIKV isolated in Brazil, we orally exposed ROCK, Higgs white eyes (HWE) and RED mosquitoes with a low-passage ZIKVBR strain
At 14 dpi, the body infection rate increased in HWE samples (65%) but significant lower prevalence (HWE x ROCK and HWE x RED, p = 0.0436) and viral levels were observed in relation to the ROCK and RED strains, which remained at the same infection rate (95%) at this time (Fig 1A)
Summary
The world is facing a new outbreak of the emerging Zika virus (ZIKV) [1]. Its association with neurological and autoimmune complications as well as infants born with microcephaly [2,3] has caused a global healthcare crisis. The outcome of vector infection will rely on the specific interactions between the mosquito and virus genotypes. Better understanding of the mosquito vectors-ZIKV interactions is the basis to generate the development of innovative strategies that can be added to the arsenal in the combat of ZIKV. Studies have reported significant differences in susceptibility for ZIKV infection between wild mosquito populations of Aedes aegypti, Aedes albopictus and other Aedes species [5,6,7]. These vector competence studies focusing on main vector species as well as variations in susceptibility of different populations from the same species are primordial to delineate improved control programs, prioritizing competent populations
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