Alternative mRNA splice variants in Drosophila 



JESO Volume 139, 2008 



ALTERNATIVE mRNA SPLICE VARIANTS IN DROSOPHILA DL2 

 CELLS FOLLOWING FLOCK HOUSE VIRUS INFECTION 



A. SKANDALIS 1 , A. ESHGHI*, M. J. BIDOCHKA 

 Department of Biological Sciences, Brock University, 

 St. Catharines, Ontario, Canada L2S 3A1 

 email: adonis. skandalis@brocku.ca 



Abstract J. ent. Soc. Ont 139: 49-58 



There is a paucity of information regarding the responses of the insect immune 

 system to viral infection. In other metazoan cells and tissues mRNA splicing 

 variants are frequently associated with viral infection. Here we analyzed 

 transcripts of the DNA repair gene 8-oxoguanine DNA glycosylase generated 

 prior to, and post, infection of Drosophila melanogaster macrophage-like 

 DL-2 cells by Flock House Virus (FHV). In mock-infected controls we 

 observed that 2% of the transcripts were incompletely processed, maintaining 

 some but not all introns. Eight hours post-FHV infection of the DL-2 cells, we 

 observed a seven fold increase in the frequency of immature Oggl transcripts. 

 Moreover, there was a change in the introns retained in the transcripts observed 

 compared with mock-infected controls, including completely unspliced 

 transcripts. Surprisingly, the frequency of immature transcripts was reduced 

 to control levels by 12 hours post-inoculation and remained relatively low up 

 to 48 hrs. These results support the conclusion that viral infection may be 

 accompanied by a host-mediated partial inhibition of mRNA splicing factors. 

 This phenomenon has the potential to generate novel splice variants that are 

 neither directly useful to the host nor the infecting virus but have the potential 

 to degrade the transmission of genetic information. To our knowledge this 

 the first report that viral infection may elicit general splicing instability in 

 insects. 



Published November 2008 



Introduction 



Multicellular host organisms have evolved under constant threat of infection 

 from viruses, and consequently they employ numerous anti-infection defenses, such as 

 inflammation, apoptosis, RNA interference, and innate and adaptive immune responses 

 (Tschopp et al. 1998; Dostert et al. 2005; Zambon et al. 2006). At the same time viruses 

 have evolved various strategies to evade host defenses and usurp the cellular machinery 

 for their own reproductive requirements (Li et al. 2002). Understanding the interactions 

 of viruses with their insect hosts is particularly important because insect viruses can cause 



1 Author to whom all correspondence should be addressed. 



* Currently at Department of Biochemistry, University of Victoria, Victoria, BC, V8P 5C2 



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