West Nile virus is characterized as a neurotropic pathogen, which can cause West Nile fever and is transmitted by mosquitoes of the genus Culex. In 2018, the Instituto Evandro Chagas performed the first isolation of a WNV strain in Brazil from a horse brain sample. The present study aimed to evaluate the susceptibility of orally infected Cx. quinquefasciatus from the Amazon region of Brazil to become infected and transmit the WNV strain isolated in 2018. Oral infection was performed with blood meal artificially infected with WNV, followed by analysis of infection, dissemination, and transmission rates, as well as viral titers of body, head, and saliva samples. At the 21st dpi, the infection rate was 100%, the dissemination rate was 80%, and the transmission rate was 77%. These results indicate that Cx. quinquefasciatus is susceptible to oral infection by the Brazilian strain of WNV and may act as a possible vector of the virus since it was detected in saliva from the 21st dpi.

Introdução: Os arbovirus são um grupo viral que realizam parte do ciclo replicativo no interior de vetores artrópodes, sendo assim mantidos na natureza. O Ilheus virus (ILHV) foi isolado pela primeira vez em 1947 em Ilhéus/BA, possui um ciclo de transmissão enzoótico onde as aves são hospedeiros de amplificação e o ser humano hospedeiro acidental e terminal, haja vista que, não produz viremia suficiente para a transmissão do vírus. Objetivo: Identificar na literatura os principais vetores artrópodes e hospedeiros vertebrados, sintomatologia da infecção, técnicas laboratoriais de diagnóstico e análises laboratoriais do comportamento viral do ILHV. Método: Revisão integrativa no qual realizou-se busca sistemática por artigos científicos nas bases de dados BVS-IEC, PubMed, SciELO e ScienceDirect, utilizando o descritor Ilheus virus. Selecionou-se 33 artigos científicos. Resultados: Dentre os artigos selecionados, 79% são artigos originais, 12% comunicações breves, 6% cartas do editor e 3% artigos de revisão. Identificou-se como principais vetores mosquitos dos gêneros Aedes e Psorophora, aves silvestres migratórias como hospedeiros de amplificação e o homem como hospedeiro acidental, desenvolvendo sintomatologia leve da infecção. Testes de isolamento viral em culturas de células, de Neutralização, Inibição da Hemaglutinação, Fixação de Complemento e testes moleculares demonstraram melhor eficácia no diagnóstico da infecção em humanos e animais e como metodologias de vigilância epidemiológica de arbovirus. Conclusões: O ILHV representa um grande problema de saúde pública em todas as regiões brasileiras em razão de sua ampla circulação, tornando o processo de diagnóstico complexo devido as reações cruzadas verificadas em testes sorológicos, assim como a semelhança sintomatológica das arboviroses, dificultando o diagnóstico clínico das infecções.

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.

West Nile virus is a flavivirus transmitted by mosquitoes, mainly of the genus Culex. In Brazil, serological studies have already indicated the circulation of the virus since 2003, with the first human case detected in 2014. The objective of the present paper is to report the first isolation of WNV in a Culex (Melanoconion) mosquito. Arthropods were collected by protected human attraction and CDC light bait, and taxonomically identified and analyzed by viral isolation, complement fixation and genomic sequencing tests. WNV was isolated from samples of Culex (Melanoconion) mosquitoes, and the sequencing analysis demonstrated that the isolated strain belonged to lineage 1a. The finding of the present study presents the first evidence of the isolation and genome sequencing of WNV in arthropods in Brazil.