West Nile Virus Vector Competency of Culex quinquefasciatus Mosquitoes in the Galápagos Islands

Abstract The West Nile virus is characterized as a neurotropic pathogen that causes the West Nile fever. It is transmitted by mosquitoes, mainly of the Culex genus. In 2018, the Evandro Chagas Institute carried out the first isolation of WNV strain from a horse brain sample and in 2021 the same institute also isolated the WNV in a pool of mosquitoes of the Culex spp. from the Carajás region (Pará). Thus, this study aimed to determine the vectorial competence of Culex quinquefasciatus from the Amazon region of Brazil for transmission the WNV Brazilian strain. Oral infection of Cx. quinquefasciatus females belonging to F1 generation was performed with infected blood with WNV. Subsequently, analysis of infection, dissemination and transmission rates was performed, as well as verification of viral titers in the samples. The study demonstrated that Cx. quinquefasciatus can act as a potential vector of WNV in Brazil, since it was found that the Brazilian strain was able to overcome the host's anatomical barriers and spread to various regions, among them in saliva, in which, despite the low viral titers identified, it had a transmission rate of 100% on the 21st day after infection.

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Insecticide resistance genes affect Culex quinquefasciatus vector competence for West Nile virus

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2018.2273 ◽

2019 ◽

Vol 286 (1894) ◽

pp. 20182273 ◽

Cited By ~ 3

Author(s):

Célestine M. Atyame ◽

Haoues Alout ◽

Laurence Mousson ◽

Marie Vazeille ◽

Mawlouth Diallo ◽

...

Keyword(s):

West Nile Virus ◽

Insecticide Resistance ◽

Culex Quinquefasciatus ◽

Rift Valley Fever Virus ◽

Vector Competence ◽

Resistance Mechanisms ◽

Transmission Efficiency ◽

West Nile ◽

Valley Fever ◽

Resistant Lines

Insecticide resistance has been reported to impact the interactions between mosquitoes and the pathogens they transmit. However, the effect on vector competence for arboviruses still remained to be investigated. We examined the influence of two insecticide resistance mechanisms on vector competence of the mosquito Culex quinquefasciatus for two arboviruses, Rift Valley Fever virus (RVFV) and West Nile virus (WNV). Three Cx. quinquefasciatus lines sharing a common genetic background were used: two insecticide-resistant lines, one homozygous for amplification of the Ester 2 locus (SA2), the other homozygous for the acetylcholinesterase ace-1 G119S mutation (SR) and the insecticide-susceptible reference line Slab. Statistical analyses revealed no significant effect of insecticide-resistant mechanisms on vector competence for RVFV. However, both insecticide resistance mechanisms significantly influenced the outcome of WNV infections by increasing the dissemination of WNV in the mosquito body, therefore leading to an increase in transmission efficiency by resistant mosquitoes. These results showed that insecticide resistance mechanisms enhanced vector competence for WNV and may have a significant impact on transmission dynamics of arboviruses. Our findings highlight the importance of understanding the impacts of insecticide resistance on the vectorial capacity parameters to assess the overall consequence on transmission.

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