Nature: Culex pipiens quinquefasciatus: a potential vector to transmit Zika virus

[sharon sanders]

Citation: Emerging Microbes & Infections (2016) 5, e102; doi:10.1038/emi.2016.102
Published online 7 September 2016
Culex pipiens quinquefasciatus: a potential vector to transmit Zika virus
OPEN

Xiao-xia Guo[SUP]1,[FONT=&quot]*http://www.nature.com/emi/journal/v5/n9/full/emi2016102a.html#note1[/SUP], Chun-xiao Li[SUP]1,[FONT=&quot]*[/FONT][/SUP], Yong-qiang Deng[SUP]2,[FONT=&quot]*[/FONT][/SUP], Dan Xing[SUP]1[/SUP], Qin-mei Liu[SUP]1[/SUP], Qun Wu[SUP]1[/SUP], Ai-juan Sun[SUP]1[/SUP], Yan-de Dong[SUP]1[/SUP], Wu-chun Cao[SUP]3[/SUP], Cheng-feng Qin[SUP]2[/SUP] and Tong-yan Zhao[SUP]1[/SUP][/FONT]

1. [SUP]1[/SUP]Department of Vector Biology and Control, State Key Laboratory of Pathogen and Biosecurity, Institute of Microbiology and Epidemiology, Beijing 100071, China
2. [SUP]2[/SUP]Department of Virology, State Key Laboratory of Pathogen and Biosecurity, Institute of Microbiology and Epidemiology, Beijing 100071, China
3. [SUP]3[/SUP]Department of Epidemiology, State Key Laboratory of Pathogen and Biosecurity, Institute of Microbiology and Epidemiology, Beijing 100071, China

Correspondence: CF Qin; TY Zhao, E-mail: qincf@bmi.ac.cn; tongyanzhao@126.com
[SUP][FONT=&quot]*[/SUP]These authors contributed equally to this work.
Received 24 June 2016; Revised 27 July 2016; Accepted 8 August 2016[/FONT]

Topof page ABSTRACT

Zika virus (ZIKV) has become a threat to global health since the outbreak in Brazil in 2015. Although ZIKV is generally considered an Aedes-transmitted pathogen, new evidence has shown that parts of the virus closely resemble Culex-transmitted viruses. Therefore, it is important to evaluate the competence of Culex species for ZIKV to understand their potential as vectors. In this study, female Culex pipiens quinquefasciatuswere orally exposed to ZIKV. Mosquito midguts, salivary glands and ovaries were tested for ZIKV to measure infection and dissemination at 2, 4, 6, 8, 12, 16 and 18 days post exposure (pe). In addition, saliva was collected from mosquitoes after infection and infant mice were bitten by infected mosquitoes to measure the transmission ability of Cx. p. quinquefasciatus. The results showed that the peak time of virus appearance in the salivary glands was day 8 pe, with 90[FONT=&quot]% infection rate and an estimated virus titer of 3.92?0.49 lg RNA copies[FONT=&quot]/[/FONT]mL. Eight of the nine infant mice had positive brains after being bitten by infected mosquitoes, which meant that Cx. p. quinquefasciatus could be infected with and transmit ZIKV following oral infection. These laboratory results clearly demonstrate the potential role ofCx. p. quinquefasciatus as a vector of ZIKV in China. Because there are quite different vector management strategies required to control Aedes (Stegomyia) species and Cx. p. quinquefasciatus, an integrated approach may be required should a Zika epidemic occur.

more..

http://www.nature.com/emi/journal/v5...i2016102a.html


hat tip @khanimambobar for the link [/FONT]

 

[sharon sanders]

Also please see:


Culex Species Mosquitoes and Zika Virus

 

[sharon sanders]

Thursday, September 08, 2016

Nature: Culex Pipiens Quinquefasciatus - A Potential Vector To Transmit Zika Virus

​

#11,719



Yesterday, in PLoS NTD: Culex quinquefasciatus Not Competent To Transmit Zika Virus- the latest in the `doCulex mosquitoes transmit Zika' debate - I remarked that `it may be a bit naive to assume we've heard the last on this . . . '.

Well, thanks to a head's up from@khanimambobar, we didn't have very long to wait. ​

No sooner had the electrons settled down from yesterday's blog, Nature's Emerging Microbes & Infections has come along with a new study on Culex carriage of Zika - one that comes to a decidedly different conclusion.


First the abstract, then I'll return with a bit more.

Culex pipiens quinquefasciatus: a potential vector to transmit Zika virus​

Open​

Xiao-xia Guo[SUP]1,*[/SUP], Chun-xiao Li[SUP]1,*[/SUP], Yong-qiang Deng[SUP]2,*[/SUP], Dan Xing[SUP]1[/SUP], Qin-mei Liu[SUP]1[/SUP], Qun Wu[SUP]1[/SUP], Ai-juan Sun[SUP]1[/SUP], Yan-de Dong[SUP]1[/SUP], Wu-chun Cao[SUP]3[/SUP], Cheng-feng Qin[SUP]2[/SUP] and Tong-yan Zhao[SUP]1[/SUP]
ABSTRACT

Zika virus (ZIKV) has become a threat to global health since the outbreak in Brazil in 2015. Although ZIKV is generally considered an Aedes-transmitted pathogen, new evidence has shown that parts of the virus closely resemble Culex-transmitted viruses. Therefore, it is important to evaluate the competence ofCulex species for ZIKV to understand their potential as vectors.

In this study, female Culex pipiens quinquefasciatus were orally exposed to ZIKV. Mosquito midguts, salivary glands and ovaries were tested for ZIKV to measure infection and dissemination at 2, 4, 6, 8, 12, 16 and 18 days post exposure (pe). In addition, saliva was collected from mosquitoes after infection and infant mice were bitten by infected mosquitoes to measure the transmission ability of Cx. p. quinquefasciatus.

The results showed that the peak time of virus appearance in the salivary glands was day 8 pe, with 90% infection rate and an estimated virus titer of 3.92?0.49 lg RNA copies/mL. Eight of the nine infant mice had positive brains after being bitten by infected mosquitoes, which meant that Cx. p. quinquefasciatus could be infected with and transmit ZIKV following oral infection.

These laboratory results clearly demonstrate the potential role of Cx. p. quinquefasciatus as a vector of ZIKV in China. Because there are quite different vector management strategies required to control Aedes (Stegomyia) species and Cx. p. quinquefasciatus, an integrated approach may be required should a Zika epidemic occur.​

(SNIP METHODS & MATERIALS)

Discussion

In this study, we demonstrated that Cx. p. quinquefasciatus was able to be infected with and transmit ZIKV after oral exposure. The IR was as high as 90% in the salivary glands and 80% in the saliva on day 8 pe. The decrease in mosquito midgut infections observed over time in our study is consistent with other published studies[SUP]31[/SUP] and was probably due to virus clearance by the mosquito’s immune system.[SUP]32, 33[/SUP]​

In the other transmission experiment, infant mice were infected after being bitten by virus-positive mosquitoes and disseminated to and replicated in the mouse brains. These findings verified the potential role of Cx. p. quinquefasciatus as a vector of ZIKV.​

(Continue . . . )​

This isn't the first time we've seen conflicting results from similar scientific studies conducted by reputable research teams (see When Flu Vaccine Studies Collide), but I don't ever recall seeing so many emerge in such a short span of time.

Six weeks ago, in Fiocruz: A Culex Mosquito With The Potential To Transmit Zika and followed up just last week in BioRxIv: Zika Virus Replication In Culex Quinquefasciatus In Brazil we looked at research by FIOCRUZ researcher Constance Ayres that strongly suggested Culex could carry and spread the Zika virus. ​

But since mid-July we've seen no fewer than four studies pretty much dismissing the idea.

PLoS NTD: Culex quinquefasciatus Not Competent To Transmit Zika Virus ​

Eurosurveillance: Experimentally Infected Culex Mosquitoes Unable To Spread Zika​

EID Journal: Culex pipiens and Aedes triseriatus Mosquito Susceptibility to Zika Virus​

To say the jury is still out on all of this is an understatement. So if you're confused, you aren't alone.

Of course, being physically able to transmit the virus in the laboratory setting, and actually contributing to the community spread of the Zika virus in a substantial and meaningful way, are two different things. ​

That said, none of these journals are lightweights, and these studies were all conducted by reputable researchers, so I'm not inclined to try to pick a side.

The best I can do is continue to update this blog whenever new information is published and hope a consensus is reached soon.​

But with nearly daily releases on Culex's competence in transmitting Zika, this one topic is beginning to feel like a full time job.



Posted by Michael Coston at 12:53 PM