Culex flavivirus infection in a Culex pipiens mosquito colony and its effects on vector competence for Rift Valley fever phlebovirus

Sandra Talavera,Ana Vázquez,Ana I Nuñez,Francesc Muñoz-Muñoz,Lotty Birnberg,Núria Busquets

doi:10.1186/s13071-018-2887-4

Abstract

BackgroundRift Valley fever is a mosquito-borne zoonotic disease that affects domestic ruminants and humans. Culex flavivirus is an insect-specific flavivirus that naturally exists in field mosquito populations. The influence of Culex flavivirus on Rift Valley fever phlebovirus (RVFV) vector competence of Culex pipiens has not been investigated.MethodsCulex flavivirus infection in a Cx. pipiens colony was studied by Culex flavivirus oral feeding and intrathoracical inoculation. Similarly, vector competence of Cx. pipiens infected with Culex flavivirus was evaluated for RVFV. Infection, dissemination, transmission rates and transmission efficiency of Culex flavivirus-infected and non-infected Cx. pipiens artificially fed with RVFV infected blood were assessed.ResultsCulex flavivirus was able to infect Cx. pipiens after intrathoracically inoculation in Cx. pipiens mosquitos but not after Culex flavivirus oral feeding. Culex flavivirus did not affect RVFV infection, dissemination and transmission in Cx. pipiens mosquitoes. RVFV could be detected from saliva of both the Culex flavivirus-positive and negative Cx. pipiens females without significant differences. Moreover, RVFV did not interfere with the Culex flavivirus infection in Cx. pipiens mosquitoes.ConclusionsCulex flavivirus infected and non-infected Cx. pipiens transmit RVFV. Culex flavivirus existing in field-collected Cx. pipiens populations does not affect their vector competence for RVFV. Culex flavivirus may not be an efficient tool for RVFV control in mosquitoes.

Highlights

Rift Valley fever is a mosquito-borne zoonotic disease that affects domestic ruminants and humans
No positive Culex flavivirus (CxFV) was recorded in any tested female mosquito on 3, 5, 7 and 10 dpe, CxFV could be detected in all mosquito samples collected on 0 dpe, demonstrating that all mosquitoes were exposed to the virus (Fig. 1)
Rift Valley fever phlebovirus (RVFV) infection, dissemination and transmission in Cx. pipiens infected and non-infected with CxFV Mosquitoes infected with CxFV and exposed to RVFV (n = 10; n = 1 hybrid form and n = 9 molestus form) and mosquitoes non-infected with CxFV and exposed to RVFV (n = 22; n = 5 hybrid form and n = 17 molestus form) were analyzed at 14 dpe

Summary

Introduction

Rift Valley fever is a mosquito-borne zoonotic disease that affects domestic ruminants and humans. Culex flavivirus is an insect-specific flavivirus that naturally exists in field mosquito populations. The influence of Culex flavivirus on Rift Valley fever phlebovirus (RVFV) vector competence of Culex pipiens has not been investigated. Culex flavivirus (CxFV) belongs to the genus Flavivirus (family Flaviviridae). Some flaviviruses are considered to be vertebrate-specific while other group of viruses of this genus are insect-specific (ISFV) [1,2,3]. Circulation of ISFVs in natural mosquito populations is likely maintained by vertical transmission [4, 5]. No co-infection studies with other pathogenic viruses belonging to other genera have been performed, such as Rift Valley fever phlebovirus (RVFV)

Objectives

Methods

Results

Discussion

Conclusion