#Vector competence of #Aedes aegypti, #Culex tarsalis, and Culex quinquefasciatus from #California for #Zika virus (PLoS Negl Trop Dis., abstract)

[Source: PLoS Neglected Tropical Diseases, full page: (LINK). Abstract, edited.]

OPEN ACCESS /  PEER-REVIEWED / RESEARCH ARTICLE

Vector competence of Aedes aegypti, Culex tarsalis, and Culex quinquefasciatus from California for Zika virus

Bradley J. Main, Jay Nicholson, Olivia C. Winokur, Cody Steiner, Kasen K. Riemersma, Jackson Stuart, Ryan Takeshita, Michelle Krasnec, Christopher M. Barker, Lark L. Coffey

Published: June 21, 2018 / DOI: https://doi.org/10.1371/journal.pntd.0006524

 

Abstract

Zika virus (ZIKV) has emerged since 2013 as a significant global human health threat following outbreaks in the Pacific Islands and rapid spread throughout South and Central America. Severe congenital and neurological sequelae have been linked to ZIKV infections. Assessing the ability of common mosquito species to transmit ZIKV and characterizing variation in mosquito transmission of different ZIKV strains is important for estimating regional outbreak potential and for prioritizing local mosquito control strategies for Aedes and Culex species. In this study, we evaluated the laboratory vector competence of Aedes aegypti, Culex quinquefasciatus, and Culex tarsalis that originated in areas of California where ZIKV cases in travelers since 2015 were frequent. We compared infection, dissemination, and transmission rates by measuring ZIKV RNA levels in cohorts of mosquitoes that ingested blood meals from type I interferon-deficient mice infected with either a Puerto Rican ZIKV strain from 2015 (PR15), a Brazilian ZIKV strain from 2015 (BR15), or an ancestral Asian-lineage Malaysian ZIKV strain from 1966 (MA66). With PR15, Cx. quinquefasciatus was refractory to infection (0%, N = 42) and Cx. tarsalis was infected at 4% (N = 46). No ZIKV RNA was detected in saliva from either Culex species 14 or 21 days post feeding (dpf). In contrast, Ae. aegypti developed infection rates of 85% (PR15; N = 46), 90% (BR15; N = 20), and 81% (MA66; N = 85) 14 or 15 dpf. Although MA66-infected Ae. aegypti showed higher levels of ZIKV RNA in mosquito bodies and legs, transmission rates were not significantly different across virus strains (P = 0.13, Fisher’s exact test). To confirm infectivity and measure the transmitted ZIKV dose, we enumerated infectious ZIKV in Ae. aegypti saliva using Vero cell plaque assays. The expectorated plaque forming units PFU varied by viral strain: MA66-infected expectorated 13±4 PFU (mean±SE, N = 13) compared to 29±6 PFU for PR15-infected (N = 13) and 35±8 PFU for BR15-infected (N = 6; ANOVA, df = 2, F = 3.8, P = 0.035). These laboratory vector competence results support an emerging consensus that Cx. tarsalis and Cx. quinquefasciatus are not vectors of ZIKV. These results also indicate that Ae. aegypti from California are efficient laboratory vectors of ancestral and contemporary Asian lineage ZIKV.

 

Author summary

Assessing the ability of common mosquito species to transmit Zika virus (ZIKV) and characterizing variation in mosquito transmission of different ZIKV strains is important for estimating regional outbreak potential and for prioritizing local mosquito control strategies for Aedes and Culex species. In this study, we evaluated the laboratory vector competence of Aedes aegypti, Culex quinquefasciatus, and Culex tarsalis that originated in areas of California where ZIKV cases in travelers since 2015 were frequent. We observed variation in infection loads between ZIKV strains in Ae. aegypti, but transmission rates were not different. In addition, there was a positive relationship between ZIKV RNA levels in infected mosquitoes ascertained from bodies and ZIKV RNA transmission rates. Our data add to the growing body of evidence supporting the role of Aedes aegypti as a ZIKV vector and refute Cx. quinquefasciatus and Cx. tarsalis as vectors.

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Citation: Main BJ, Nicholson J, Winokur OC, Steiner C, Riemersma KK, Stuart J, et al. (2018) Vector competence of Aedes aegypti, Culex tarsalis, and Culex quinquefasciatusfrom California for Zika virus. PLoS Negl Trop Dis 12(6): e0006524. https://doi.org/10.1371/journal.pntd.0006524

Editor: Michael J. Turell, INDEPENDENT RESEARCHER, UNITED STATES

Received: March 19, 2018; Accepted: May 11, 2018; Published: June 21, 2018

Copyright: © 2018 Main 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 paper.

Funding: Primary funding for this work was provided by Abt Associates and a consortium of vector control districts in California: Coachella Valley, Orange County, Greater Los Angeles County, San Gabriel Valley, West Valley, Kern, Butte County, Tulare, Sacramento-Yolo, Placer, and Turlock. OCW and CMB also acknowledge financial support from NASA Health and Air Quality grant NNX15AF36G, and CMB and LLC acknowledge funding support from the Pacific Southwest Regional Center of Excellence for Vector-Borne Diseases funded by the U.S. Centers for Disease Control and Prevention (Cooperative Agreement 1U01CK000516). KKR was supported by a National Institutes of Health Ruth L. Kirschstein National Research Service Award T32 OD O11147. Part of this work was supported by start-up funds provided to LLC by the Pathology, Microbiology and Immunology Department in the School of Veterinary Medicine at UC Davis. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. One funder, Abt Associates, provided support in the form of salaries for authors [MK and RT], but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are articulated in the ‘author contributions’ section.

Competing interests: Michelle Krasnec and Ryan Takeshita are/were employed by Abt Associates. Abt Associates provided support in the form of salaries for authors [MK and RT], but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are articulated in the ‘author contributions’ section.

Keywords: Zika Virus; Mosquitoes; USA; California; Aedes aegypti; Culex quinquefasciatus; Culex tarsalis.

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Giuseppe Michieli

I am an Italian blogger, active since 2005 with main focus on emerging infectious diseases such as avian influenza, SARS, antibiotics resistance, and many other global Health issues. Other fields of interest are: climate change, global warming, geological and biological sciences. My activity consists mainly in collection and analysis of news, public services updates, confronting sources and making decision about what are the 'signals' of an impending crisis (an outbreak, for example). When a signal is detected, I follow traces during the entire course of an event. I started in 2005 my blog ''A TIME'S MEMORY'', now with more than 40,000 posts and 3 millions of web interactions. Subsequently I added an Italian Language blog, then discontinued because of very low traffic and interest. I contributed for seven years to a public forum (FluTrackers.com) in the midst of the Ebola epidemic in West Africa in 2014, I left the site to continue alone my data tracking job.