Zika virus replication in the mosquitoCulex quinquefasciatusin Brazil

Abstract

These authors contributed equally to this work. Abstract:Zika virus (ZIKV) is a flavivirus that has recently been associated with increased incidence of neonatal microcephaly and other neurological disorders. The virus is primarily transmitted by mosquito bite, although other routes of infection have been implicated in some cases. The Aedes aegypti mosquito is considered to be the main vector to humans worldwide, but there is evidence of other mosquito species, including Culex quinquefasciatus, playing a role in the Brazilian outbreak. To test this hypothesis, we experimentally compared the vectorial competence of laboratory-reared A. aegypti and C. quinquefasciatus. We found ZIKV in the not peer-reviewed) is the author/funder. All rights reserved. No reuse allowed without permission.The copyright holder for this preprint (which was . http://dx.doi.org/10.1101/073197 doi: bioRxiv preprint first posted online Sep. 2, 2016; 2 midgut, salivary glands, and saliva of artificially fed C. quinquefasciatus. Additionally, we collected ZIKV-infected C. quinquefasciatus from urban areas of high microcephaly incidence in Recife, Brazil. Take into account; these findings indicate that there may be a wider range of vectors for ZIKV than anticipated.Keywords: Zika, microcephaly, Culex, Aedes, vectorial competence, vector control.Zika is classically considered a mild disease whose symptoms include fever, joint pain, rash and, in some cases, conjunctivitis (1). However, the Zika outbreak in Brazil has been associated with an increased incidence of neonatal microcephaly and neurological disorders (2, 3). Zika virus (ZIKV) is a poorly known, small, enveloped RNA virus with ssRNA (+) belonging to the Family Flaviviridae. It was first isolated in April 1947 from a rhesus monkey and in January 1948 from the mosquito species Aedes africanus (4). Since then, several ZIKV strains have been isolated from many samples, mostly mosquitoes, including species from the genera Aedes, Mansonia, Anopheles and Culex (5).The first known Zika epidemic in an urban environment occurred in Micronesia in 2007, with approximately 73% of the human population on Yap island becoming infected (6).Intriguingly, although many Aedes mosquitoes were collected in the field and evaluated for virus detection, no samples were found to be positive for ZIKV (6). Additionally, it is important to highlight that Aedes aegypti (A. aegypti) is absent from most islands in the Micronesia archipelago and is very rare on the islands where it is present (6, 7).There is a global consensus among scientists and health agencies that Aedes spp. are the main ZIKV vector in urban areas (WHO, 2016). This is in part because vector competence experiments for ZIKV have been conducted exclusively for species of this genus, mainly A.aegypti (8, 9). Previous laboratory studies (8, 10) suggested that A. aegypti is a ZIKV vector. not peer-reviewed) is the author/funder. All rights reserved. No reuse allowed without permission.The copyright holder for this preprint (which was . http://dx.doi...

Culex quinquefasciatus mosquitoes do not support replication of Zika virus

“…quinquefasciatus confirm that these mosquitoes are not competent for ZIKV transmission. Using field-collected Culex mosquitoes and ZIKV strains isolated from patients in the northeast region of Brazil as performed by Guedes et al [38], Fernandes et al [61] showed that Cx. quinquefasciatus populations were not competent for transmitting the virus.…”

“…pipiens complex were not able to experimentally transmit ZIKV and no viral particles were detected in mosquito saliva up to 21 days after exposure to an infectious blood meal [17-20, 25, 29-36], though different results were recorded with other Cx. quinquefasciatus strains [37,38]. Even after injection of a high dose of ZIKV into the mosquito thorax, thus bypassing the midgut barrier, viral replication was reported to be poor in Culex mosquitoes and no viral particles were isolated from saliva [32] To assess the potential mechanism(s) underlying the blocking of ZIKV in Culex mosquitoes, we evaluated the ability of ZIKV to orally infect two lines of Cx.…”

“…pipiens complex originated from all continents challenged with ZIKV virus isolates from all lineages failed to show competence for this virus [17, 18, 20, . There would only be two conflicting results [37,38]. The reasons for this remain unclear but it is important to analyse each case in more detail to rule out unexpected circumstances.…”

After all, How is the Zika Virus Transmitted?

“…Culex spp. are susceptible to ZIKV infection and able to effectively transmit ZIKV [34,35]. On the other hand, other studies suggest that this vector may not have competence to transmit ZIKV [18,32,33,[35][36][37].…”

Zika Virus: What Have We Learnt Since the Start of the Recent Epidemic?

“…On the other hand, the vector competence is the innate capability to acquire and sustain the pathogen, and transmit it to a host, so many experiments on competence were performed in alternative vectors, mainly with Cx pipiens and Cx quinquefasciatus. The results showed arguments that support (Franca et al, 2016;Guedes et al, 2016;Guo et al, 2016) or reject (Aliota et al, 2016b;Amraoui et al, 2016;Boccolini et al, 2016;Fernandes et al, 2016;HallMendelin et al, 2016;Huang Y.J. et al, 2016;Weger-Lucarelli et al, 2016;Hart et al, 2017) Culex vector competence.…”