West Nile Virus interactions with viruses usually infecting the most probable West Nile Virus vectors

Pathogenic arboviruses have been the focus of many investigations. However, in the vectors that carry them, other viruses are also present. Interactions between them have been less studied. One such example is that of the flaviviruses. This genus contains important public health challenges such as West Nile. In recent years, many new flaviviruses have been described, most of them belonging to the so called “mosquito only flaviviruses” group. Other new mosquito only viruses such as birna, alpha, mesoni or negeviruses have also been recently described. With the aim of initiating an investigation about the interactions between viruses circulating in Spain and Italy, we have conducted systematic virus isolation in C636 cells from mosquito pools. When cythopatic effect was detected, isolates were analyzed by electron microscopy, consensus PCR and/or sequencing (by generic primers and high throughput sequencing systems). Sixty six pools of mosquitoes of the species Culex pipiens, Cx. modestus, Cx perexiguus, Ochlerotatus caspius and Aedes albopictus were collected in Spain. Eighteen viruses were identified (11 flavi, 2 reo, 3 parvo (1 denso), 1 ortorthobunya and 1 negevirus). Fifty two pools of the species Cx pipiens, Cx modestus and Ae albopictus were collected in Italy. Fourteen viruses were identified (6 reo, 4 rhabdo 5 flavi, 1 birna, 2 parvo and 2 negeviruses). Most of the positive pools contained two or three viruses. Thus, it is possible that a mosquito could be infected with more than one agent. Possible implication of these will be discussed