Mosquito excreta: a sample type with many potential applications for the investigation of Ross River virus and West Nile virus ecology

Ramirez Lopez, Ana L., Hall-Mendelin, Sonja, Doggett, Stephen L., Hewitson, Glen R., Mcmahon, Jamie L., Ritchie, Scott A., and van den Hurk, Andrew F. (2018) Mosquito excreta: a sample type with many potential applications for the investigation of Ross River virus and West Nile virus ecology. PLoS Neglected Tropical Diseases, 12 (8). e0006771.

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BACKGROUND: Emerging and re-emerging arthropod-borne viruses (arboviruses) cause human and animal disease globally. Field and laboratory investigation of mosquito-borne arboviruses requires analysis of mosquito samples, either individually, in pools, or a body component, or secretion such as saliva. We assessed the applicability of mosquito excreta as a sample type that could be utilized during studies of Ross River and West Nile viruses, which could be applied to the study of other arboviruses.

METHODOLOGY/PRINCIPAL FINDINGS: Mosquitoes were fed separate blood meals spiked with Ross River virus and West Nile virus. Excreta was collected daily by swabbing the bottom of containers containing batches and individual mosquitoes at different time points. The samples were analyzed by real-time RT-PCR or cell culture enzyme immunoassay. Viral RNA in excreta from batches of mosquitoes was detected continuously from day 2 to day 15 post feeding. Viral RNA was detected in excreta from at least one individual mosquito at all timepoints, with 64% and 27% of samples positive for RRV and WNV, respectively. Excretion of viral RNA was correlated with viral dissemination in the mosquito. The proportion of positive excreta samples was higher than the proportion of positive saliva samples, suggesting that excreta offers an attractive sample for analysis and could be used as an indicator of potential transmission. Importantly, only low levels of infectious virus were detected by cell culture, suggesting a relatively low risk to personnel handling mosquito excreta.

CONCLUSIONS/SIGNIFICANCE: Mosquito excreta is easily collected and provides a simple and efficient method for assessing viral dissemination, with applications ranging from vector competence experiments to complementing sugar-based arbovirus surveillance in the field, or potentially as a sample system for virus discovery.

Item ID: 58621
Item Type: Article (Research - C1)
ISSN: 1935-2735
Copyright Information: © 2018 Ramırez 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.
Funders: National Health and Medical Research Council of Australia (NHMRC), Australian Institute of Tropical Health and Medicine (AITHM), James Cook University
Projects and Grants: NHMRC 1131932, NHMRC 1044698
Date Deposited: 13 Jun 2019 02:18
FoR Codes: 32 BIOMEDICAL AND CLINICAL SCIENCES > 3207 Medical microbiology > 320705 Medical virology @ 100%
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