Upregulation of a novel eukaryotic translation initiation factor 5A (eIF5A) in dengue 2 virus-infected mosquito cells

Through this technique, we identified a novel eukaryotic translation initiation factor 5A (eIF5A) which is upregulated in Aedes albopictus-derived C6/36 cells infected by the type 2 dengue (Den-2) virus. The full-length of the identified eIF5A gene consisted of 1498 bp of nucleotides with a 41.39% G+C content, and it possessed a higher similarity and shorter evolutionary distance with insects than with other organisms. Upregulation of eIF5A in response to Den-2 virus infection was validated at both the RNA and protein levels. This phenomenon was also observed by confocal microscopy. In addition, cell death obviously occurred when eIF5A activity was inhibited in C6/36 cells even when they were infected by the virus. However, viral multiplication was not obviously affected in infected C6/36 cells when eIF5A activity was reduced.Taken together, we postulated that eIF5A plays a role in preventing mosquito cells from death in response to Den-2 viral infection, thus facilitating continued viral growth and potential persistent infection in mosquito cells. It would be worthwhile to further investigate how its downstream factors or cofactors contribute to this phenomenon of dengue infection.The dengue virus, one of the flaviviruses, contains ~11 kilobase (kb) single-stranded, positive-sense genomic RNA [1]. Within host cells, viral RNA directly translates into a single polyprotein that is subsequently cleaved into three structural proteins and seven nonstructural proteins [2]. The process is carried out by the combined action of host proteases and a trypsin-like viral NS2B/NS3 serine protease [3].The dengue virus is transmitted between humans by mosquitoes, implying that both mammalian and mosquito cells are susceptible to the virus [4]. Mammalian cells with dengue virus infection usually end up undergoing apoptosis due to shutdown of protein synthesis in the host cell [5]. However, dengue and other arboviruses frequently occur in mosquito cells without causing obvious delet