Genetic characterization of an insect-specific flavivirus isolated from Culex theileri mosquitoes collected in southern Portugal

Ricardo Parreira,Shelley Cook,Ângela Lopes,António Pedro De Matos,António Paulo Gouveia De Almeida,João Piedade,Aida Esteves

doi:10.1016/j.virusres.2012.04.010

Ricardo Parreira, Shelley Cook + Show 5 more

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https://doi.org/10.1016/j.virusres.2012.04.010

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Abstract

We describe the full genetic characterization of an insect-specific flavivirus (ISF) from Culex theileri (Theobald) mosquitoes collected in Portugal. This represents the first isolation and full characterization of an ISF from Portuguese mosquitoes. The virus, designated CTFV, for Culex theileri flavivirus, was isolated in the C6/36 Stegomyia albopicta (=Aedes albopictus) cell line, and failed to replicate in vertebrate (Vero) cells in common with other ISFs. The CTFV genome encodes a single polyprotein with 3357 residues showing all the features expected for those of flaviviruses. Phylogenetic analyses based on all ISF sequences available to date, place CTFV among Culex-associated flaviviruses, grouping with recently published NS5 partial sequences documented from mosquitoes collected in the Iberian Peninsula, and with Quang Binh virus (isolated in Vietnam) as a close relative. No CTFV sequences were found integrated in their host's genome using a range of specific PCR primers designed to the prM/E, NS3, and NS5 region.

Highlights

The genus Flavivirus (Flaviviridae) includes over seven dozen known enveloped viruses with ssRNA (+) genomes encoding a single polyprotein which is co-translationally processed by viral and host proteases into structural, and non-structural proteins, that play critical roles in viral replication (Lindenbach and Rice, 2003)
This was different from the cytopathic effect (CPE) seen in C6/36 cell cultures infected with the Cell fusing agent virus (CFAV), which typically exhibit differently sized syncytia (Fig. 1C)
No complete sequence for these Culex-associated viruses was ever reported by Vázquez et al (2012), our analysis suggests that Culex theileri flaviviruses (CTFV) circulate widely in the Iberian Peninsula

Summary

Introduction

The genus Flavivirus (Flaviviridae) includes over seven dozen known enveloped viruses with ssRNA (+) genomes encoding a single polyprotein which is co-translationally processed by viral and host proteases into structural, and non-structural proteins, that play critical roles in viral replication (Lindenbach and Rice, 2003). The analysis of a large number of mosquitoes in natural populations indicates that these viruses form a genetically diverse group with a wider geographical dispersion, and prevalence, than initially suspected (Blitvich et al, 2009; Crabtree et al, 2003; Cook et al, 2006; Farfan-Ale et al, 2009; Hoshino et al, 2007, 2009; Morales-Betoulle et al, 2008)

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