[Source: PLoS Neglected Tropical Diseases, full page: (LINK). Abstract, edited.]
OPEN ACCESS / PEER-REVIEWED / RESEARCH ARTICLE
Vector competence of Australian Aedes aegypti and Aedes albopictus for an epidemic strain of Zika virus
R. Leon E. Hugo , Liesel Stassen , Jessica La, Edward Gosden, O’mezie Ekwudu, Clay Winterford, Elvina Viennet, Helen M. Faddy, Gregor J. Devine, Francesca D. Frentiu
Published: April 4, 2019 / DOI: https://doi.org/10.1371/journal.pntd.0007281 / This is an uncorrected proof.
Recent epidemics of Zika virus (ZIKV) in the Pacific and the Americas have highlighted its potential as an emerging pathogen of global importance. Both Aedes (Ae.) aegypti and Ae. albopictus are known to transmit ZIKV but variable vector competence has been observed between mosquito populations from different geographical regions and different virus strains. Since Australia remains at risk of ZIKV introduction, we evaluated the vector competence of local Ae. aegypti and Ae. albopictus for a Brazilian epidemic ZIKV strain. In addition, we evaluated the impact of daily temperature fluctuations around a mean of 28°C on ZIKV transmission and extrinsic incubation period.
Mosquitoes were orally challenged with a Brazilian ZIKV strain (8.8 log CCID50/ml) and maintained at either 28°C constant or fluctuating temperature conditions. At 3, 7 and 14 days post-infection (dpi), ZIKV RNA copies were quantified in mosquito bodies, as well as wings and legs, using qRT-PCR, while virus antigen in saliva (a proxy for transmission) was detected using a cell culture ELISA. Despite high body and disseminated infection rates in both vectors, the transmission rates of ZIKV in saliva of Ae. aegypti (50–60%) were significantly higher than in Ae. albopictus (10%) at 14 dpi. Both species supported a high viral load in bodies, with no significant differences between constant and fluctuating temperature conditions. However, a significant difference in viral load in wings and legs between species was observed, with higher titres in Ae. aegypti maintained at constant temperature conditions. For ZIKV transmission to occur in Ae. aegypti, a disseminated virus load threshold of 7.59 log10 copies had to be reached.
Australian Ae. aegypti are better able to transmit a Brazilian ZIKV strain than Ae. albopictus. The results are in agreement with the global consensus that Ae. aegypti is the major vector of ZIKV.
Zika virus (ZIKV) is a mosquito-borne pathogen that generally causes a mild febrile illness but mostly remains asymptomatic in 50–80% of infections. Infection during pregnancy can cause congenital malformations, notably microcephaly. In adults, it can cause Guillain-Barré syndrome. The recent ZIKV epidemic in the Americas has been linked to the urban vector Aedes aegypti. The presence of the species in Australia makes the region vulnerable to emerging mosquito-borne viruses. A mosquito’s competence to transmit a pathogen will depend on both the virus and vector strains. Here, we determine the vector competence of Australian Ae. aegypti and Ae. albopictus mosquitoes for a ZIKV epidemic strain, originating from the epicentre of the Brazilian outbreak, under constant and fluctuating temperatures that simulate field environments in Australia. Our results demonstrate that, although both species were susceptible to ZIKV infection, Ae. aegypti is more likely to transmit virus. Our results may aid in the formulation of public health strategies to mitigate the threat of ZIKV.
Citation: Hugo RLE, Stassen L, La J, Gosden E, Ekwudu O, Winterford C, et al. (2019) Vector competence of Australian Aedes aegypti and Aedes albopictus for an epidemic strain of Zika virus. PLoS Negl Trop Dis 13(4): e0007281. https://doi.org/10.1371/journal.pntd.0007281
Editor: Lyric C. Bartholomay, University of Wisconsin Madison, UNITED STATES
Received: October 22, 2018; Accepted: March 5, 2019; Published: April 4, 2019
Copyright: © 2019 Hugo et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Data Availability: All relevant data are within the manuscript and its Supporting Information files.
Funding: Funding was provided by the Australia National Health and Medical Research Council (NHMRC) grant number APP1125317 to FDF and GJD, an Australian Infectious Diseases seed grant “Zika virus vector biology, diagnostics and vaccines” (Pls Young, Hall and Devine), and a donation from John and Elizabeth Hunter. Australian governments fund the Australian Red Cross Blood Service to provide blood, blood products and services to the Australian community. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing interests: The authors have declared that no competing interests exist.
Keywords: Zika Virus; Mosquitoes; Aedes aegypti; Aedes albopictus; Australia.