Vector competence of Australian Aedes aegypti and Aedes albopictus for an epidemic strain of Zika virus

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

doi:10.1371/journal.pntd.0007281

Vector competence of Australian Aedes aegypti and Aedes albopictus for an epidemic strain of Zika virus

PLoS Negl Trop Dis. 2019 Apr 4;13(4):e0007281. doi: 10.1371/journal.pntd.0007281. eCollection 2019 Apr.

Authors

Affiliations

¹ Mosquito Control Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia.
² Institute of Health and Biomedical Innovation, and School of Biomedical Sciences Queensland University of Technology, Brisbane, Queensland, Australia.
³ QIMR Berghofer Histotechnology Facility, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia.
⁴ Research and Development, Australian Red Cross Blood Service, Brisbane, Queensland, Australia.

Abstract

Background: 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.

Methodology/principal findings: 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.

Conclusions/significance: 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.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Aedes / virology*
Animals
Australia / epidemiology
Brazil
Mosquito Vectors / virology*
RNA, Viral / analysis
Saliva / virology
Temperature
Viral Load
Wings, Animal / virology
Zika Virus / genetics
Zika Virus / pathogenicity
Zika Virus Infection / transmission*

Substances

RNA, Viral

Grants and 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.