Characterization of insect-specific Culex flavivirus (Flaviviridae) nucleotide sequences in mosquitoes from urban parks in São Paulo, Brazil

ABSTRACT Background: Despite their worldwide occurrence, the distribution and role of insect-specific flaviviruses (ISFs) remain unclear. Methods: We evaluated the presence of ISFs in mosquitoes collected in São Paulo, Brazil, using reverse transcription and semi-nested polymerase chain reaction (PCR). Some of the positive samples were subjected to nanopore sequencing. Results: Twelve mosquito pools (2.8%) tested positive for flavivirus infection. Nanopore sequencing was successfully performed on six samples. Phylogenetic analysis grouped these sequences into genotype 2 of Culex flavivirus (CxFV). Conclusions: The identification of CxFV genotype 2 at new locations in São Paulo highlights the importance of understanding the role of ISFs in mosquito vector competence.

Superinfection exclusion studies using West Nile virus and Culex flavivirus strains from Argentina

In Argentina, many Flavivirus were recognised including West Nile virus (WNV). During 2009 several strains of Culex Flavivirus (CxFV), an insect-specific flavivirus, were isolated in the same region where circulation of WNV was detected. Hence, the objective of this study was to analyse the effect of co-infection in vitro assays using CxFV and WNV Argentinean strains in order to evaluate if CxFV could affect WNV replication. Our results showed that WNV replication was suppressed when multiplicity of infection (MOI) for CxFV was 10 or 100 times higher than WNV. Nevertheless, in vivo assays are necessary in order to evaluate the superinfection exclusion potential.

Identification of Culex Flavivirus by deep sequencing approach in Xinjiang, China / 中华微生物学和免疫学杂志

Objective To investigate the diversity of mosquito-borne viruses in Xinjiang , China, and to identify mosquitos-borne viruses of medical importance rapidly .Methods The virus-derived RNAs in mosquitos captured in wild were screened and confirmed by using Illumina deep sequencing approach and reverse transcription PCR , respectively .The alignment analysis was performed by using gene sequences from GenBank.Results One hundred and forty-four Culex Flavivirus ( CxFV, Flavivirus genus, Flaviviridae) specific sequences were identified .The overlapping reads were assembled into 7 uncontinuous viral genomic contigs.The gaps between the contigs were further filled by RT-PCR products, which resulted in reconstruc-tion of viral genomic 5′and 3′terminus (687 nt and 411 nt).Phylogenetic analysis showed that the newly identified CxFV belonged to America/Asian genotype , which specifically clustered into a clade with other CxFV strains from China mainland ,sharing 98.2%-99.5%homologies in nucleotide sequences and 99.5%in amino acids sequences among them .Conclusion Illumina deep sequencing approach was successfully applied to arthropod-borne virus surveillance .The recently emerged Culex Flavivirus was detected for the first time in Xinjiang, China.