Role of non-coding sequences in Arenavirus mRNAs translation

FOSCALDI SABRINA; ALEJANDRA DANTUONO; LOPEZ, NORA

Granada

Congreso; XV International Conference on Negative Strand Viruses; 2013

NSV OC

The genome of Tacaribe virus (TCRV), prototype of the New World arenaviruses, comprises two RNA segments each encoding two proteins in an ambisense orientation. TCRV coding sequences are expressed from subgenomic messenger RNAs (mRNAs) transcribed from the 3´ regions of the genomes and antigenomes. Viral mRNAs contain cap structure and short stretches of non-viral nucleotides upstream of viral 5? untranslated regions (UTR). Also, they lack a 3? poly(A) tail, exhibiting a 3? non-coding region predicted to form stable secondary hairpin structures with a suspected role in translation. To analyze the contribution of non-coding sequences to TCRV mRNAs translation, we generated a synthetic transcript mimicking the TCRV Nucleoprotein (N) mRNA, which contains the Firefly Luciferase (LUC) open reading frame. Mutant mRNAs were designed to carry modifications in either the 5? or the 3? non-coding sequence. Translation from these virus-like mRNAs in transfected cells was evidenced by LUC activity. Deletion of the complete 5? UTR caused loss of LUC activity, while significantly reduced levels of reporter gene activity were associated to deletion of the 3? non-coding region, suggesting that both 5? and 3? non-coding sequences stimulate virus-like mRNA translation. Studies are underway to define the role of viral proteins and to identify structural signatures in viral mRNAs that may modulate their translation.